Passive solar building design
Encyclopedia
In passive solar building design, windows, walls, and floors are made to collect, store, and distribute solar energy in the form of heat in the winter and reject solar heat in the summer. This is called passive solar design or climatic design because, unlike active solar heating systems, it doesn't involve the use of mechanical and electrical devices.
The key to designing a passive solar building is to best take advantage of the local climate
. Elements to be considered include window placement and glazing type, thermal insulation
, thermal mass
, and shading. Passive solar design techniques can be applied most easily to new buildings, but existing buildings can be adapted or "retrofitted".
). Such technologies convert sunlight into usable heat (water, air, thermal mass), cause air-movement for ventilating, or future use, with little use of other energy sources. A common example is a solarium on the equator
-side of a building. Passive cooling
is the use of the same design principles to reduce summer cooling requirements.
Some passive systems use a small amount of conventional energy to control dampers, shutters, night insulation, and other devices that enhance solar energy collection, storage, use, and reduce undesirable heat transfer
.
Passive solar technologies include direct and indirect solar gain
for space heating, solar water heating
systems based on the thermosiphon
or geyser pump, use of thermal mass
and phase-change materials
for slowing indoor air temperature swings, solar cooker
s, the solar chimney
for enhancing natural ventilation, and earth sheltering
.
More widely, passive solar technologies include the solar furnace
and solar forge, but these typically require some external energy for aligning their concentrating mirrors or receivers, and historically have not proven to be practical or cost effective for widespread use. 'Low-grade' energy needs, such as space and water heating, have proven, over time, to be better applications for passive use of solar energy.
, thermodynamics
( particularly heat transfer
: conduction (heat), convection
, and electromagnetic radiation
), fluid mechanics
/ natural convection
(passive movement of air and water without the use of electricity, fans or pumps), and human thermal comfort
based on heat index
, psychrometrics
and enthalpy
control for buildings to be inhabited by humans or animals, sunrooms, solariums, and greenhouse
s for raising plants.
Specific attention is divided into: the site, location and solar orientation of the building, local sun path
, the prevailing level of insolation
( latitude
/ sunshine / clouds / precipitation (meteorology)
), design and construction quality / materials, placement / size / type of windows and walls, and incorporation of solar-energy-storing thermal mass
with heat capacity
.
While these considerations may be directed toward any building, achieving an ideal optimized cost / performance solution requires careful holistic system integration
engineering
of these scientific principles. Modern refinements
through computer modeling (such as the comprehensive U.S. Department of Energy "Energy Plus" energy simulation software, and application of decades of lessons learned (since the 1970s energy crisis) can achieve significant energy savings and reduction of environmental damage, without sacrificing functionality or aesthetics. In fact, passive-solar design features such as a greenhouse / sunroom / solarium can greatly enhance the livability, daylight, views, and value of a home, at a low-cost per unit of space.
Much has been learned about Passive Solar Building Design since the 1970s energy crisis. Many unscientific intuition-based expensive construction experiments have attempted and failed to achieve zero energy
- the total elimination of heating-and-cooling energy bills.
One of the most useful "after-the-fact" quick-evaluation tools has been the use of thermography
full-color digital thermal imaging cameras for a formal quantitative scientific energy audit
. In an instant, they can irrefutably document areas of bad thermal performance, ( such as the negative thermal impact of roof-angled glass or a skylight on a cold winter night or hot summer day ). One serious problem of after-the-fact problem documentation is that it can waste a lot of time and capital investment on bad ideas, when passive-solar experiments are based on unscientific intuition (like common misunderstanding of sunrooms and greenhouse
s with roof-angled glazing, etc.).
The scientific lessons learned over the last three decades have been captured in sophisticated comprehensive energy simulation computer software systems (like U.S. DOE Energy Plus, et al.), which take time for a scientist or engineer to learn how to use.
Passive Solar Building Construction may not be difficult or expensive (using off-the-shelf existing materials and technology), but the Scientific Passive Solar Building Design Process is a non-trivial advanced engineering effort that requires significant study of previous counter-intuitive lessons learned, and time to enter, evaluate, and iteratively-refine the computer simulation input and output.
Scientific Passive Solar Building Design with quantitative cost benefit product optimization
is not easy for a novice. The level of complexity has resulted in ongoing bad-architecture, and many intuition-based unscientific construction experiments that disappoint their designers and waste a significant portion of their construction budget on inappropriate ideas.
The economic motivation for scientific design and engineering is significant. If it had been applied comprehensively to new building construction beginning in 1980 (based on 1970's lessons learned), America could be saving over $250,000,000 per year on expensive energy and related pollution today.
Since 1979, Passive Solar Building Design has been a critical element of achieving zero energy
by educational institution experiments, and governments around the world, including the U.S. Department of Energy, and the energy research scientists that they have supported for decades. The cost effective proof of concept
was established decades ago, but cultural assimilation
into architecture, construction trades, and building-owner decision making
has been very slow and difficult to change.
The new terms "Architectural Science" and "Architectural Technology" are being added to some schools of Architecture, with a future goal of teaching the above scientific and energy-engineering principles.
The ability to achieve these goals simultaneously is fundamentally dependent on the seasonal variations in the sun's path throughout the day.
This occurs as a result of the inclination
of the Earth's axis of rotation in relation to its orbit
. The sun path
is unique for any given latitude.
In Northern Hemisphere non-tropical latitudes farther than 23.5 degrees from the equator:
The converse is observed in the Southern Hemisphere, but the sun rises to the east and sets toward the west regardless of which hemisphere you are in.
In equatorial regions at less than 23.5 degrees, the position of the sun at solar noon
will oscillate from north to south and back again during the year.
In regions closer than 23.5 degrees from either north-or-south pole, during summer the sun will trace a complete circle in the sky without setting whilst it will never appear above the horizon six months later, during the height of winter.
The 47-degree difference in the altitude of the sun at solar noon between winter and summer forms the basis of passive solar design. This information is combined with local climatic data (degree day
) heating and cooling requirements to determine at what time of the year solar gain will be beneficial for thermal comfort
, and when it should be blocked with shading. By strategic placement of items such as glazing and shading devices, the percent of solar gain entering a building can be controlled throughout the year.
One passive solar sun path design problem is that although the sun is in the same relative position six weeks before, and six weeks after, the solstice, due to "thermal lag" from the thermal mass
of the Earth, the temperature and solar gain requirements are quite different before and after the summer or winter solstice. Movable shutters, shades, shade screens, or window quilts can accommodate day-to-day and hour-to-hour solar gain and insulation requirements.
Careful arrangement of rooms completes the passive solar design. A common recommendation for residential dwellings is to place living areas facing solar noon and sleeping quarters on the opposite side. A heliodon
is a traditional movable light device used by architects and designers to help model sun path effects. In modern times, 3D computer graphics can visually simulate this data, and calculate performance predictions.
is a function of personal health factors (medical, psychological, sociological and situational),ambient air temperature, mean radiant temperature
, air movement (wind chill
, turbulence
) and relative humidity
(affecting human evaporative
cooling). Heat transfer
in buildings occurs through convection
, conduction
, and thermal radiation
through roof, walls, floor and windows.
can be beneficial or detrimental. Uncontrolled air infiltration from poor weatherization
/ weatherstripping / draft-proofing can contribute up to 40% of heat loss during winter, however strategic placement of operable windows or vents can enhance convection, cross-ventilation, and summer cooling when the outside air is of a comfortable temperature and relative humidity
. Filtered energy recovery ventilation systems may be useful to eliminate undesirable humidity, dust, pollen, and microorganisms in unfiltered ventilation air.
Natural convection causing rising
warm air and falling cooler air can result in an uneven stratification of heat. This may cause uncomfortable variations in temperature in the upper and lower conditioned space, serve as a method of venting hot air, or be designed in as a natural-convection air-flow loop for passive solar heat distribution and temperature equalization. Natural human cooling by perspiration and evaporation
may be facilitated through natural or forced convective air movement by fans, but ceiling fans can disturb the stratified insulating air layers at the top of a room, and accelerate heat transfer from a hot attic, or through nearby windows. In addition, high relative humidity
inhibits evaporative cooling by humans.
is radiant energy
, and the primary source is the sun. Solar radiation occurs predominantly through the roof and windows (but also through walls). Thermal radiation
moves from a warmer surface to a cooler one. Roofs receive the majority of the solar radiation delivered to a house. A cool roof
, or green roof
in addition to a radiant barrier
can help prevent your attic from becoming hotter than the peak summer outdoor air temperature (see albedo
, absorptivity, emissivity
, and reflectivity
).
Windows are a ready and predictable site for thermal radiation
.
Energy from radiation can move into a window in the day time, and out of the same window at night. Radiation uses photon
s to transmit electromagnetic waves through a vacuum, or translucent medium. Solar heat gain can be significant even on cold clear days. Solar heat gain through windows can be reduced by insulated glazing
, shading, and orientation. Windows are particularly difficult to insulate compared to roof and walls. Convective heat transfer
through and around window covering
s also degrade its insulation properties. When shading windows, external shading is more effective at reducing heat gain than internal window covering
s.
Western and eastern sun can provide warmth and lighting, but are vulnerable to overheating in summer if not shaded. In contrast, the low midday sun readily admits light and warmth during the winter, but can be easily shaded with appropriate length overhangs or angled louvres during summer. The amount of radiant heat received is related to the location latitude
, altitude
, cloud cover
, and seasonal / hourly angle of incidence
(see Sun path
and Lambert's cosine law
).
Another passive solar design principle is that thermal energy can be stored
in certain building materials and released again when heat gain eases to stabilize diurnal
(day/night) temperature variations. The complex interaction of thermodynamic principles can be counterintuitive
for first-time designers. Precise computer modeling
can help avoid costly construction experiments.
The precise amount of equator-facing glass and thermal mass should be based on careful consideration of latitude, altitude, climatic conditions, and heating/cooling degree day
requirements.
Factors that can degrade thermal performance:
theoretical limit is around 11%.
Passive solar fraction (PSF) is the percentage of the required heat load met by PSH and hence represents potential reduction in heating costs. RETScreen International has reported a PSF of 20-50%. Within the field of sustainability
, energy conservation even of the order of 15% is considered substantial.
Other sources report the following PSFs:
In favorable climates such as the southwest United States, highly optimized systems can exceed 75% PSF.
The cost effectiveness of these configurations are currently being investigated in great detail and are demonstrating promising results.
(e.g. water tank, masonry wall) and slowly transmitted indirectly to the building through conduction and convection
.
Efficiency can suffer from slow response (thermal lag) and heat losses at night. Other issues include the cost of insulated glazing
and developing effective systems to redistribute heat throughout the living area.
. Heat gain can occur through a sunspace, solarium or solar closet. These areas may also be employed usefully as a greenhouse or drying cabinet. An equator-side sun room may have its exterior windows higher than the windows between the sun room and the interior living space, to allow the low winter sun to penetrate to the cold side of adjacent rooms. Glass placement and overhangs prevent solar gain during the summer. Earth cooling tubes
or other passive cooling
techniques can keep a solarium cool in the summer.
Measures should be taken to reduce heat loss at night e.g. window coverings or movable window insulation
Examples:
keeps the building warm when the sun can't heat it.
In diurnal solar houses, the storage is designed for one or a few days. The usual method is a custom-constructed thermal mass. These include a Trombe wall
, a ventilated concrete floor, a cistern, water wall or roof pond.
In subarctic areas, or areas that have long terms without solar gain (e.g. weeks of freezing fog), purpose-built thermal mass is very expensive. Don Stephens pioneered an experimental technique to use the ground as thermal mass large enough for annualized heat storage. His designs run an isolated thermosiphon 3m under a house, and insulate the ground with a 6m waterproof skirt.
or superinsulation
(type, placement and amount) reduces unwanted leakage of heat. Some passive buildings are actually constructed of insulation.
systems is significantly enhanced by insulative (e.g. double glazing), spectrally selective glazing (low-e
), or movable window insulation (window quilts, bifold interior insulation shutters, shades, etc.).
Generally, Equator-facing windows should not employ glazing coatings that inhibit solar gain.
There is extensive use of super-insulated windows in the German
Passive House
standard. Selection of different spectrally selective window coating depends on the ratio of heating versus cooling degree day
s for the design location.
and multiple panes of glass can reduce useful solar gain. However, direct-gain systems are more dependent on double or triple glazing
to reduce heat loss. Indirect-gain and isolated-gain configurations may still be able to function effectively with only single-pane glazing. Nevertheless, the optimal cost-effective solution is both location and system dependent.
. When the winter sun is low on the horizon, most solar radiation reflects off of roof angled glass ( the angle of incidence
is nearly parallel to roof-angled glass morning and afternoon ). When the summer sun is high, it is nearly perpendicular to roof-angled glass, which maximizes solar gain at the wrong time of year, and acts like a solar furnace. Skylights should be covered and well-insulated to reduce natural convection
( warm air rising ) heat loss on cold winter nights, and intense solar heat gain during hot spring/summer/fall days.
The equator-facing side of a building is south in the northern hemisphere, and north in the southern hemisphere. Skylights on roofs that face away from the equator provide mostly-indirect illumination, except for summer days when the sun rises on the non-equator side of the building (depending on latitude
). Skylights on east-facing roofs provide maximum direct light and solar heat gain in the summer morning. West-facing skylights provide afternoon sunlight and heat gain during the hottest part of the day.
Some skylights have expensive glazing that partially reduces summer solar heat gain, while still allowing some visible light transmission. However, if visible light can pass through it, so can some radiant heat gain (they are both electromagnetic radiation
waves.
You can partially reduce some of the unwanted roof-angled-glazing summer solar heat gain by installing a skylight in the shade of deciduous
(leaf-shedding) trees, or by adding a movable insulated opaque window covering on the inside or outside of the skylight. This would eliminate the daylight benefit in the summer. If tree limbs hang over a roof, they will increase problems with leaves in rain gutters, possibly cause roof-damaging ice dams, shorten roof life, and provide an easier path for pests to enter your attic. Leaves and twigs on skylights are unappealing, difficult to clean, and can increase the glazing breakage risk in wind storms.
"Sawtooth roof glazing" with vertical-glass-only can bring some of the passive solar building design benefits into the core of a commercial or industrial building, without the need for any roof-angled glass or skylights.
Skylights provide daylight. The only view they provide is essentially straight up in most applications. Well-insulated light tube
s can bring daylight into northern rooms, without using a skylight. A passive-solar greenhouse provides abundant daylight for the equator-side of the building.
Infrared thermography
color thermal imaging cameras ( used in formal energy audit
s ) can quickly document the negative thermal impact of roof-angled glass or a skylight on a cold winter night or hot summer day.
The U.S. Department of Energy states: "vertical glazing is the overall best option for sunspaces." Roof-angled glass and sidewall glass are not recommended for passive solar sunspaces.
The U.S. DOE explains drawbacks to roof-angled glazing: Glass and plastic have little structural strength. When installed vertically, glass (or plastic) bears its own weight because only a small area (the top edge of the glazing) is subject to gravity. As the glass tilts off the vertical axis, however, an increased area (now the sloped cross-section) of the glazing has to bear the force of gravity. Glass is also brittle; it does not flex much before breaking. To counteract this, you usually must increase the thickness of the glazing or increase the number of structural supports to hold the glazing. Both increase overall cost, and the latter will reduce the amount of solar gain into the sunspace.
Another common problem with sloped glazing is its increased exposure to the weather. It is difficult to maintain a good seal on roof-angled glass in intense sunlight. Hail, sleet, snow, and wind may cause material failure. For occupant safety, regulatory agencies usually require sloped glass to be made of safety glass, laminated, or a combination thereof, which reduce solar gain potential. Most of the roof-angled glass on the Crowne Plaza Hotel Orlando Airport sunspace was destroyed in a single windstorm. Roof-angled glass increases construction cost, and can increase insurance premiums. Vertical glass is less susceptible to weather damage than roof-angled glass.
It is difficult to control solar heat gain in a sunspace with sloped glazing during the summer and even during the middle of a mild and sunny winter day. Skylights are the antithesis of zero energy building
Passive Solar Cooling in climates with an air conditioning requirement.
striking glass within 20 degrees of perpendicular
is mostly transmitted through the glass, whereas sunlight at more than 35 degrees from perpendicular is mostly reflected
All of these factors can be modeled more precisely with a photographic light meter
and a heliodon
or optical bench, which can quantify the ratio of reflectivity
to transmissivity
, based on angle of incidence
.
Alternatively, passive solar computer software can determine the impact of sun path
, and cooling-and-heating degree day
s on energy
performance. Regional climatic conditions are often available from local weather services.
Although the sun is at the same altitude 6-weeks before and after the solstice, the heating and cooling requirements before and after the solstice are significantly different. Heat storage on the Earth's surface causes "thermal lag." Variable cloud cover influences solar gain potential. This means that latitude-specific fixed window overhangs, while important, are not a complete seasonal solar gain control solution.
Control mechanisms (such as manual-or-motorized interior insulated drapes, shutters, exterior roll-down shade screens, or retractable awnings) can compensate for differences caused by thermal lag or cloud cover, and help control daily / hourly solar gain requirement variations.
Home automation
systems that monitor temperature, sunlight, time of day, and room occupancy can precisely control motorized window-shading-and-insulation devices.
. Using information on a Color
for electromagnetic radiation
to determine its thermal radiation
properties of reflection or absorption can assist the choices.
See Lawrence Berkeley National Laboratory and Oak Ridge National Laboratory: "Cool Colors"
materials for careful passive solar choices include hardscape
building material and "softscape
" plant
s. The use of landscape design
principles for selection of trees, hedges, and trellis
-pergola
features with vine
s; all can be used to create summer shading. For winter solar gain it is desirable to use deciduous
plants that drop their leaves in the autumn gives year round passive solar benefits. Non-deciduous evergreen
shrub
s and trees can be windbreak
s, at variable heights and distances, to create protection and shelter from winter wind chill
. Xeriscaping
with 'mature size appropriate' native species
of-and drought tolerant plants
, drip irrigation
, mulching, and organic gardening practices reduce or eliminate the need for energy-and-water-intensive irrigation
, gas powered garden equipment, and reduces the landfill waste footprint. Solar powered landscape lighting and fountain pumps, and covered swimming pool
s and plunge pool
s with solar water heaters
can reduce the impact of such amenities.
illumination
for interiors, and so reduce reliance on artificial lighting systems.
This can be achieved by careful building design, orientation, and placement of window sections to collect light. Other creative solutions involve the use of reflecting surfaces to admit daylight into the interior of a building. Window sections should be adequately sized, and to avoid over-illumination
can be shielded with a Brise soleil
, awning
s, well placed trees, glass coatings, and other passive and active devices.
Another major issue for many window
systems is that they can be potentially vulnerable sites of excessive thermal gain or heat loss. Whilst high mounted clerestory
window and traditional skylights can introduce daylight in poorly oriented sections of a building, unwanted heat transfer may be hard to control. Thus, energy that is saved by reducing artificial lighting is often more than offset by the energy required for operating HVAC
systems to maintain thermal comfort
.
Various methods can be employed to address this including but not limited to window covering
s, insulated glazing
and novel materials such as aerogel
semi-transparent insulation, optical fiber
embedded in walls or roof, or hybrid solar lighting at Oak Ridge National Laboratory.
collectors, such as light shelves, lighter wall and floor colors, mirror
ed wall sections, interior walls with upper glass panels, and clear or translucent glassed hinged door
s and sliding glass doors take the captured light and passively reflect it further inside. The light can be from passive windows or skylights and solar light tube
s or from active daylighting
sources. In traditional Japanese architecture
the Shōji
sliding panel doors, with translucent Washi
screens, are an original precedent. International style
, Modernist
and Mid-century modern
architecture
were earlier innovators of this passive penetration and reflection in industrial, commercial, and residential applications.
to heat water for domestic use. Different active-and-passive solar hot water
technologies have different location-specific economic cost benefit analysis implications.
Fundamental passive solar hot water heating involves no pumps or anything electrical. It is very cost effective in climates that do not have lengthy sub-freezing, or very-cloudy, weather conditions. Other active solar water heating technologies, etc. may be more appropriate for some locations.
It is possible to have active solar hot water which is also capable of being "off grid" and qualifies as sustainable. This is done by the use of a photovoltaic cell which uses energy from the sun to power the pumps.
(Passivhaus in German) Institute in Germany. Rather than relying solely on traditional passive solar design techniques, this approach seeks to make use of all passive sources of heat, minimises energy usage, and emphasises the need for high levels of insulation reinforced by meticulous attention to detail in order to address thermal bridging and cold air infiltration. Most of the buildings built to the Passive House standard also incorporate an active heat recovery ventilation
unit with or without a small (typically 1 kW) incorporated heating component.
The energy design of Passive House buildings is developed using a spreadsheet-based modeling tool called the Passive House Planning Package (PHPP) which is updated periodically. The current version is PHPP2007, where 2007 is the year of issue. A building may be certified as a 'Passive House' when it can be shown that it meets certain criteria, the most important being that the annual specific heat demand for the house should not exceed 15kWh/m2a.
was used to simulate the altitude and azimuth of the sun shining on a model building at any time of any day of the year. In modern times, computer programs can model this phenomenon and integrate local climate data (including site impacts such as overshadowing
and physical obstructions) to predict the solar gain potential for a particular building design over the course of a year. GPS-based smartphone
applications can now do this inexpensively on a hand held device. These tools provide the passive solar designer the ability to evaluate local conditions, design elements and orientation prior to construction. Energy performance optimization normally requires an iterative-refinement design-and-evaluate process. There is no such thing as a "one-size-fits-all" universal passive solar building design that would work well in all locations.
. This will then radiate
heat into the building in the evening. This can be a problem in the summer, especially on western walls in areas with high degree day cooling requirements. External shading, or a radiant barrier plus air gap, may be used to reduce undesirable summer solar gain.
for use months later during the cold season ("annualised passive solar.") Increased storage is achieved by employing large amounts of thermal mass or earth coupling. Anecdotal reports suggest they can be effective but no formal study has been conducted to demonstrate their superiority.
The approach also can move cooling into the warm season.
Examples:
Passive solar building design sometimes uses limited electrical and mechanical controls to operate dampers, insulating shutters, shades, awnings, or reflectors. Some systems enlist small fans or solar-heated chimneys to improve convective air-flow. A reasonable way to analyse these systems is by measuring their coefficient of performance. A heat pump might use 1 J for every 4 J it delivers giving a COP of 4. A system that only uses a 30 W fan to more-evenly distribute 10 kW of solar heat through an entire house would have a COP of 300.
. Although a ZEB uses multiple passive solar building design concepts, a ZEB is usually not purely passive, having active mechanical renewable energy generation systems such as: wind turbine
, photovoltaics
, micro hydro
, geothermal
, and other emerging alternative energy sources.
Energy Rating systems
Solar-designers
The key to designing a passive solar building is to best take advantage of the local climate
Climate
Climate encompasses the statistics of temperature, humidity, atmospheric pressure, wind, rainfall, atmospheric particle count and other meteorological elemental measurements in a given region over long periods...
. Elements to be considered include window placement and glazing type, thermal insulation
Thermal insulation
Thermal insulation is the reduction of the effects of the various processes of heat transfer between objects in thermal contact or in range of radiative influence. Heat transfer is the transfer of thermal energy between objects of differing temperature...
, thermal mass
Thermal mass
Thermal mass is a concept in building design which describes how the mass of the building provides "inertia" against temperature fluctuations, sometimes known as the thermal flywheel effect...
, and shading. Passive solar design techniques can be applied most easily to new buildings, but existing buildings can be adapted or "retrofitted".
Passive energy gain
Passive solar technologies use sunlight without active mechanical systems (as contrasted to active solarActive solar
Active solar technologies are employed to convert solar energy into another more useful form of energy. This would normally be a conversion to heat or electrical energy. Inside a building this energy would be used for heating, cooling, or off-setting other energy use or costs. Active solar uses...
). Such technologies convert sunlight into usable heat (water, air, thermal mass), cause air-movement for ventilating, or future use, with little use of other energy sources. A common example is a solarium on the equator
Equator
An equator is the intersection of a sphere's surface with the plane perpendicular to the sphere's axis of rotation and containing the sphere's center of mass....
-side of a building. Passive cooling
Passive cooling
Passive cooling refers to technologies or design features used to cool buildings without power consumption, such as those technologies discussed in the Passive house project.-Passive cooling:...
is the use of the same design principles to reduce summer cooling requirements.
Some passive systems use a small amount of conventional energy to control dampers, shutters, night insulation, and other devices that enhance solar energy collection, storage, use, and reduce undesirable heat transfer
Heat transfer
Heat transfer is a discipline of thermal engineering that concerns the exchange of thermal energy from one physical system to another. Heat transfer is classified into various mechanisms, such as heat conduction, convection, thermal radiation, and phase-change transfer...
.
Passive solar technologies include direct and indirect solar gain
Solar gain
Solar gain refers to the increase in temperature in a space, object or structure that results from solar radiation...
for space heating, solar water heating
Solar hot water
Solar water heating or solar hot water systems comprise several innovations and many mature renewable energy technologies that have been well established for many years...
systems based on the thermosiphon
Thermosiphon
Thermosiphon refers to a method of passive heat exchange based on natural convection which circulates liquid without the necessity of a mechanical pump...
or geyser pump, use of thermal mass
Thermal mass
Thermal mass is a concept in building design which describes how the mass of the building provides "inertia" against temperature fluctuations, sometimes known as the thermal flywheel effect...
and phase-change materials
Phase Change Material
A phase-change material is a substance with a high heat of fusion which, melting and solidifying at a certain temperature, is capable of storing and releasing large amounts of energy...
for slowing indoor air temperature swings, solar cooker
Solar cooker
A solar cooker, or solar oven, is a device which uses the energy of sunlight to heat food or drink to cook it or sterilize it. High-tech versions, for example electric ovens powered by solar cells, are possible, and have some advantages such as being able to work in diffuse light. However at...
s, the solar chimney
Solar chimney
A solar chimney — often referred to as a thermal chimney — is a way of improving the natural ventilation of buildings by using convection of air heated by passive solar energy...
for enhancing natural ventilation, and earth sheltering
Earth sheltering
Earth sheltering is the architectural practice of using earth against building walls for external thermal mass, to reduce heat loss, and to easily maintain a steady indoor air temperature...
.
More widely, passive solar technologies include the solar furnace
Solar furnace
A solar furnace is a structure that captures sunlight to produce high temperatures, usually for industry. This is done with a curved mirror that acts as a parabolic reflector, concentrating light onto a focal point...
and solar forge, but these typically require some external energy for aligning their concentrating mirrors or receivers, and historically have not proven to be practical or cost effective for widespread use. 'Low-grade' energy needs, such as space and water heating, have proven, over time, to be better applications for passive use of solar energy.
As a science
The scientific basis for Passive Solar Building Design has been developed from a combination of climatologyClimatology
Climatology is the study of climate, scientifically defined as weather conditions averaged over a period of time, and is a branch of the atmospheric sciences...
, thermodynamics
Thermodynamics
Thermodynamics is a physical science that studies the effects on material bodies, and on radiation in regions of space, of transfer of heat and of work done on or by the bodies or radiation...
( particularly heat transfer
Heat transfer
Heat transfer is a discipline of thermal engineering that concerns the exchange of thermal energy from one physical system to another. Heat transfer is classified into various mechanisms, such as heat conduction, convection, thermal radiation, and phase-change transfer...
: conduction (heat), convection
Convection
Convection is the movement of molecules within fluids and rheids. It cannot take place in solids, since neither bulk current flows nor significant diffusion can take place in solids....
, and electromagnetic radiation
Electromagnetic radiation
Electromagnetic radiation is a form of energy that exhibits wave-like behavior as it travels through space...
), fluid mechanics
Fluid mechanics
Fluid mechanics is the study of fluids and the forces on them. Fluid mechanics can be divided into fluid statics, the study of fluids at rest; fluid kinematics, the study of fluids in motion; and fluid dynamics, the study of the effect of forces on fluid motion...
/ natural convection
Natural convection
Natural convection is a mechanism, or type of heat transport, in which the fluid motion is not generated by any external source but only by density differences in the fluid occurring due to temperature gradients. In natural convection, fluid surrounding a heat source receives heat, becomes less...
(passive movement of air and water without the use of electricity, fans or pumps), and human thermal comfort
Thermal comfort
Thermal comfort is a term used by the American Society of Heating, Refrigerating and Air-Conditioning Engineers, an international body. It is defined as the state of mind in humans that expresses satisfaction with the surrounding environment...
based on heat index
Heat index
The heat index is an index that combines air temperature and relative humidity in an attempt to determine the human-perceived equivalent temperature — how hot it feels, termed the felt air temperature. The human body normally cools itself by perspiration, or sweating, which evaporates and carries...
, psychrometrics
Psychrometrics
Psychrometrics or psychrometry or Hygrometry are terms used to describe the field of engineering concerned with the determination of physical and thermodynamic properties of gas-vapor mixtures...
and enthalpy
Enthalpy
Enthalpy is a measure of the total energy of a thermodynamic system. It includes the internal energy, which is the energy required to create a system, and the amount of energy required to make room for it by displacing its environment and establishing its volume and pressure.Enthalpy is a...
control for buildings to be inhabited by humans or animals, sunrooms, solariums, and greenhouse
Greenhouse
A greenhouse is a building in which plants are grown. These structures range in size from small sheds to very large buildings...
s for raising plants.
Specific attention is divided into: the site, location and solar orientation of the building, local sun path
Sun path
Sun path refers to the apparent significant seasonal-and-hourly positional changes of the sun as the Earth rotates, and orbits around the sun. The relative position of the sun is a major factor in the heat gain of buildings and in the performance of solar energy systems...
, the prevailing level of insolation
Insolation
Insolation is a measure of solar radiation energy received on a given surface area in a given time. It is commonly expressed as average irradiance in watts per square meter or kilowatt-hours per square meter per day...
( latitude
Latitude
In geography, the latitude of a location on the Earth is the angular distance of that location south or north of the Equator. The latitude is an angle, and is usually measured in degrees . The equator has a latitude of 0°, the North pole has a latitude of 90° north , and the South pole has a...
/ sunshine / clouds / precipitation (meteorology)
Precipitation (meteorology)
In meteorology, precipitation In meteorology, precipitation In meteorology, precipitation (also known as one of the classes of hydrometeors, which are atmospheric water phenomena is any product of the condensation of atmospheric water vapor that falls under gravity. The main forms of precipitation...
), design and construction quality / materials, placement / size / type of windows and walls, and incorporation of solar-energy-storing thermal mass
Thermal mass
Thermal mass is a concept in building design which describes how the mass of the building provides "inertia" against temperature fluctuations, sometimes known as the thermal flywheel effect...
with heat capacity
Heat capacity
Heat capacity , or thermal capacity, is the measurable physical quantity that characterizes the amount of heat required to change a substance's temperature by a given amount...
.
While these considerations may be directed toward any building, achieving an ideal optimized cost / performance solution requires careful holistic system integration
System integration
In engineering, system integration is the bringing together of the component subsystems into one system and ensuring that the subsystems function together as a system...
engineering
Engineering
Engineering is the discipline, art, skill and profession of acquiring and applying scientific, mathematical, economic, social, and practical knowledge, in order to design and build structures, machines, devices, systems, materials and processes that safely realize improvements to the lives of...
of these scientific principles. Modern refinements
History of passive solar building design
-Pre-modern History:The techniques of passive solar building design were practiced for thousands of years, by necessity, before the advent of mechanical heating and cooling. It has remained a traditional part of vernacular architecture in many countries...
through computer modeling (such as the comprehensive U.S. Department of Energy "Energy Plus" energy simulation software, and application of decades of lessons learned (since the 1970s energy crisis) can achieve significant energy savings and reduction of environmental damage, without sacrificing functionality or aesthetics. In fact, passive-solar design features such as a greenhouse / sunroom / solarium can greatly enhance the livability, daylight, views, and value of a home, at a low-cost per unit of space.
Much has been learned about Passive Solar Building Design since the 1970s energy crisis. Many unscientific intuition-based expensive construction experiments have attempted and failed to achieve zero energy
Zero energy building
A zero-energy building, also known as a zero net energy building, Net-Zero Energy Building , or Net Zero Building, is a popular term to describe a building with zero net energy consumption and zero carbon emissions annually. Zero energy buildings can be independent from the energy grid supply...
- the total elimination of heating-and-cooling energy bills.
One of the most useful "after-the-fact" quick-evaluation tools has been the use of thermography
Thermography
Infrared thermography, thermal imaging, and thermal video are examples of infrared imaging science. Thermal imaging cameras detect radiation in the infrared range of the electromagnetic spectrum and produce images of that radiation, called thermograms...
full-color digital thermal imaging cameras for a formal quantitative scientific energy audit
Energy audit
An energy audit is an inspection, survey and analysis of energy flows for energy conservation in a building, process or system to reduce the amount of energy input into the system without negatively affecting the output.-Principle:...
. In an instant, they can irrefutably document areas of bad thermal performance, ( such as the negative thermal impact of roof-angled glass or a skylight on a cold winter night or hot summer day ). One serious problem of after-the-fact problem documentation is that it can waste a lot of time and capital investment on bad ideas, when passive-solar experiments are based on unscientific intuition (like common misunderstanding of sunrooms and greenhouse
Greenhouse
A greenhouse is a building in which plants are grown. These structures range in size from small sheds to very large buildings...
s with roof-angled glazing, etc.).
The scientific lessons learned over the last three decades have been captured in sophisticated comprehensive energy simulation computer software systems (like U.S. DOE Energy Plus, et al.), which take time for a scientist or engineer to learn how to use.
Passive Solar Building Construction may not be difficult or expensive (using off-the-shelf existing materials and technology), but the Scientific Passive Solar Building Design Process is a non-trivial advanced engineering effort that requires significant study of previous counter-intuitive lessons learned, and time to enter, evaluate, and iteratively-refine the computer simulation input and output.
Scientific Passive Solar Building Design with quantitative cost benefit product optimization
Product optimization
Product optimization is the practice of making changes or adjustments to a product to make it more desirable.-Description:A product has a number of attributes. For example, a soda bottle can have different packaging variations, flavors, nutritional values. It is possible to optimize a product by...
is not easy for a novice. The level of complexity has resulted in ongoing bad-architecture, and many intuition-based unscientific construction experiments that disappoint their designers and waste a significant portion of their construction budget on inappropriate ideas.
The economic motivation for scientific design and engineering is significant. If it had been applied comprehensively to new building construction beginning in 1980 (based on 1970's lessons learned), America could be saving over $250,000,000 per year on expensive energy and related pollution today.
Since 1979, Passive Solar Building Design has been a critical element of achieving zero energy
Zero energy building
A zero-energy building, also known as a zero net energy building, Net-Zero Energy Building , or Net Zero Building, is a popular term to describe a building with zero net energy consumption and zero carbon emissions annually. Zero energy buildings can be independent from the energy grid supply...
by educational institution experiments, and governments around the world, including the U.S. Department of Energy, and the energy research scientists that they have supported for decades. The cost effective proof of concept
Proof of concept
A proof of concept or a proof of principle is a realization of a certain method or idea to demonstrate its feasibility, or a demonstration in principle, whose purpose is to verify that some concept or theory that has the potential of being used...
was established decades ago, but cultural assimilation
Cultural assimilation
Cultural assimilation is a socio-political response to demographic multi-ethnicity that supports or promotes the assimilation of ethnic minorities into the dominant culture. The term assimilation is often used with regard to immigrants and various ethnic groups who have settled in a new land. New...
into architecture, construction trades, and building-owner decision making
Decision making
Decision making can be regarded as the mental processes resulting in the selection of a course of action among several alternative scenarios. Every decision making process produces a final choice. The output can be an action or an opinion of choice.- Overview :Human performance in decision terms...
has been very slow and difficult to change.
The new terms "Architectural Science" and "Architectural Technology" are being added to some schools of Architecture, with a future goal of teaching the above scientific and energy-engineering principles.
The solar path in passive design
This occurs as a result of the inclination
Inclination
Inclination in general is the angle between a reference plane and another plane or axis of direction.-Orbits:The inclination is one of the six orbital parameters describing the shape and orientation of a celestial orbit...
of the Earth's axis of rotation in relation to its orbit
Orbit
In physics, an orbit is the gravitationally curved path of an object around a point in space, for example the orbit of a planet around the center of a star system, such as the Solar System...
. The sun path
Sun path
Sun path refers to the apparent significant seasonal-and-hourly positional changes of the sun as the Earth rotates, and orbits around the sun. The relative position of the sun is a major factor in the heat gain of buildings and in the performance of solar energy systems...
is unique for any given latitude.
In Northern Hemisphere non-tropical latitudes farther than 23.5 degrees from the equator:
- The sun will reach its highest pointNoonNoon is usually defined as 12 o'clock in the daytime. The word noon is also used informally to mean midday regarding the location of the sun not the middle of a persons day. Although this is a time around the middle of the day when people in many countries take a lunch break...
toward the South (in the direction of the equator) - As winter solsticeSolsticeA solstice is an astronomical event that happens twice each year when the Sun's apparent position in the sky, as viewed from Earth, reaches its northernmost or southernmost extremes...
approaches, the angle at which the sun risesSunriseSunrise is the instant at which the upper edge of the Sun appears above the horizon in the east. Sunrise should not be confused with dawn, which is the point at which the sky begins to lighten, some time before the sun itself appears, ending twilight...
and setsSunsetSunset or sundown is the daily disappearance of the Sun below the horizon in the west as a result of Earth's rotation.The time of sunset is defined in astronomy as the moment the trailing edge of the Sun's disk disappears below the horizon in the west...
progressively moves further toward the South and the daylight hours will become shorter - The opposite is noted in summer where the sun will rise and set further toward the North and the daylight hours will lengthen
The converse is observed in the Southern Hemisphere, but the sun rises to the east and sets toward the west regardless of which hemisphere you are in.
In equatorial regions at less than 23.5 degrees, the position of the sun at solar noon
Noon
Noon is usually defined as 12 o'clock in the daytime. The word noon is also used informally to mean midday regarding the location of the sun not the middle of a persons day. Although this is a time around the middle of the day when people in many countries take a lunch break...
will oscillate from north to south and back again during the year.
In regions closer than 23.5 degrees from either north-or-south pole, during summer the sun will trace a complete circle in the sky without setting whilst it will never appear above the horizon six months later, during the height of winter.
The 47-degree difference in the altitude of the sun at solar noon between winter and summer forms the basis of passive solar design. This information is combined with local climatic data (degree day
Degree day
A degree day is a measure of heating or cooling. Totalized degree days from an appropriate starting date are used to plan the planting of crops and management of pests and pest control timing...
) heating and cooling requirements to determine at what time of the year solar gain will be beneficial for thermal comfort
Thermal comfort
Thermal comfort is a term used by the American Society of Heating, Refrigerating and Air-Conditioning Engineers, an international body. It is defined as the state of mind in humans that expresses satisfaction with the surrounding environment...
, and when it should be blocked with shading. By strategic placement of items such as glazing and shading devices, the percent of solar gain entering a building can be controlled throughout the year.
One passive solar sun path design problem is that although the sun is in the same relative position six weeks before, and six weeks after, the solstice, due to "thermal lag" from the thermal mass
Thermal mass
Thermal mass is a concept in building design which describes how the mass of the building provides "inertia" against temperature fluctuations, sometimes known as the thermal flywheel effect...
of the Earth, the temperature and solar gain requirements are quite different before and after the summer or winter solstice. Movable shutters, shades, shade screens, or window quilts can accommodate day-to-day and hour-to-hour solar gain and insulation requirements.
Careful arrangement of rooms completes the passive solar design. A common recommendation for residential dwellings is to place living areas facing solar noon and sleeping quarters on the opposite side. A heliodon
Heliodon
A heliodon is a device for adjusting the angle between a flat surface and a beam of light to match the angle between a horizontal plane at a specific latitude and the solar beam. Heliodons are used primarily by architects and students of architecture...
is a traditional movable light device used by architects and designers to help model sun path effects. In modern times, 3D computer graphics can visually simulate this data, and calculate performance predictions.
Passive solar thermodynamic principles
Personal thermal comfortThermal comfort
Thermal comfort is a term used by the American Society of Heating, Refrigerating and Air-Conditioning Engineers, an international body. It is defined as the state of mind in humans that expresses satisfaction with the surrounding environment...
is a function of personal health factors (medical, psychological, sociological and situational),ambient air temperature, mean radiant temperature
Mean radiant temperature
The Mean Radiant Temperature is a concept arising from the fact that the net exchange of radiant energy between two objects is approximately proportional to their temperature difference multiplied by their ability to emit and absorb heat . Mean radiant temperature is simply the area weighted mean...
, air movement (wind chill
Wind chill
Wind chill is the felt air temperature on exposed skin due to wind. The wind chill temperature is always lower than the air temperature, and the windchill is undefined at the higher temps...
, turbulence
Turbulence
In fluid dynamics, turbulence or turbulent flow is a flow regime characterized by chaotic and stochastic property changes. This includes low momentum diffusion, high momentum convection, and rapid variation of pressure and velocity in space and time...
) and relative humidity
Relative humidity
Relative humidity is a term used to describe the amount of water vapor in a mixture of air and water vapor. It is defined as the partial pressure of water vapor in the air-water mixture, given as a percentage of the saturated vapor pressure under those conditions...
(affecting human evaporative
Evaporation
Evaporation is a type of vaporization of a liquid that occurs only on the surface of a liquid. The other type of vaporization is boiling, which, instead, occurs on the entire mass of the liquid....
cooling). Heat transfer
Heat transfer
Heat transfer is a discipline of thermal engineering that concerns the exchange of thermal energy from one physical system to another. Heat transfer is classified into various mechanisms, such as heat conduction, convection, thermal radiation, and phase-change transfer...
in buildings occurs through convection
Convection
Convection is the movement of molecules within fluids and rheids. It cannot take place in solids, since neither bulk current flows nor significant diffusion can take place in solids....
, conduction
Heat conduction
In heat transfer, conduction is a mode of transfer of energy within and between bodies of matter, due to a temperature gradient. Conduction means collisional and diffusive transfer of kinetic energy of particles of ponderable matter . Conduction takes place in all forms of ponderable matter, viz....
, and thermal radiation
Thermal radiation
Thermal radiation is electromagnetic radiation generated by the thermal motion of charged particles in matter. All matter with a temperature greater than absolute zero emits thermal radiation....
through roof, walls, floor and windows.
Convective heat transfer
Convective heat transferConvective heat transfer
Convective heat transfer, often referred to as convection, is the transfer of heat from one place to another by the movement of fluids. The presence of bulk motion of the fluid enhances the heat transfer between the solid surface and the fluid. Convection is usually the dominant form of heat...
can be beneficial or detrimental. Uncontrolled air infiltration from poor weatherization
Weatherization
Weatherization or weatherproofing is the practice of protecting a building and its interior from the elements, particularly from sunlight, precipitation, and wind, and of modifying a building to reduce energy consumption and optimize energy efficiency.Weatherization is distinct from building...
/ weatherstripping / draft-proofing can contribute up to 40% of heat loss during winter, however strategic placement of operable windows or vents can enhance convection, cross-ventilation, and summer cooling when the outside air is of a comfortable temperature and relative humidity
Relative humidity
Relative humidity is a term used to describe the amount of water vapor in a mixture of air and water vapor. It is defined as the partial pressure of water vapor in the air-water mixture, given as a percentage of the saturated vapor pressure under those conditions...
. Filtered energy recovery ventilation systems may be useful to eliminate undesirable humidity, dust, pollen, and microorganisms in unfiltered ventilation air.
Natural convection causing rising
Stack effect
Stack effect is the movement of air into and out of buildings, chimneys, flue gas stacks, or other containers, and is driven by buoyancy. Buoyancy occurs due to a difference in indoor-to-outdoor air density resulting from temperature and moisture differences. The result is either a positive or...
warm air and falling cooler air can result in an uneven stratification of heat. This may cause uncomfortable variations in temperature in the upper and lower conditioned space, serve as a method of venting hot air, or be designed in as a natural-convection air-flow loop for passive solar heat distribution and temperature equalization. Natural human cooling by perspiration and evaporation
Evaporation
Evaporation is a type of vaporization of a liquid that occurs only on the surface of a liquid. The other type of vaporization is boiling, which, instead, occurs on the entire mass of the liquid....
may be facilitated through natural or forced convective air movement by fans, but ceiling fans can disturb the stratified insulating air layers at the top of a room, and accelerate heat transfer from a hot attic, or through nearby windows. In addition, high relative humidity
Relative humidity
Relative humidity is a term used to describe the amount of water vapor in a mixture of air and water vapor. It is defined as the partial pressure of water vapor in the air-water mixture, given as a percentage of the saturated vapor pressure under those conditions...
inhibits evaporative cooling by humans.
Radiative heat transfer
The main source of heat transferHeat transfer
Heat transfer is a discipline of thermal engineering that concerns the exchange of thermal energy from one physical system to another. Heat transfer is classified into various mechanisms, such as heat conduction, convection, thermal radiation, and phase-change transfer...
is radiant energy
Radiant energy
Radiant energy is the energy of electromagnetic waves. The quantity of radiant energy may be calculated by integrating radiant flux with respect to time and, like all forms of energy, its SI unit is the joule. The term is used particularly when radiation is emitted by a source into the...
, and the primary source is the sun. Solar radiation occurs predominantly through the roof and windows (but also through walls). Thermal radiation
Thermal radiation
Thermal radiation is electromagnetic radiation generated by the thermal motion of charged particles in matter. All matter with a temperature greater than absolute zero emits thermal radiation....
moves from a warmer surface to a cooler one. Roofs receive the majority of the solar radiation delivered to a house. A cool roof
Cool roof
Cool roofs are the roofs that can deliver high solar reflectance and high thermal emittance...
, or green roof
Green roof
A green roof is a roof of a building that is partially or completely covered with vegetation and a growing medium, planted over a waterproofing membrane. It may also include additional layers such as a root barrier and drainage and irrigation systems...
in addition to a radiant barrier
Radiant barrier
Radiant barriers or reflective barriers inhibit heat transfer by thermal radiation. Thermal energy may also be transferred via conduction or convection, however, and radiant barriers do not necessarily protect against heat transfer via conduction or convection....
can help prevent your attic from becoming hotter than the peak summer outdoor air temperature (see albedo
Albedo
Albedo , or reflection coefficient, is the diffuse reflectivity or reflecting power of a surface. It is defined as the ratio of reflected radiation from the surface to incident radiation upon it...
, absorptivity, emissivity
Emissivity
The emissivity of a material is the relative ability of its surface to emit energy by radiation. It is the ratio of energy radiated by a particular material to energy radiated by a black body at the same temperature...
, and reflectivity
Reflectivity
In optics and photometry, reflectivity is the fraction of incident radiation reflected by a surface. In general it must be treated as a directional property that is a function of the reflected direction, the incident direction, and the incident wavelength...
).
Windows are a ready and predictable site for thermal radiation
Thermal radiation
Thermal radiation is electromagnetic radiation generated by the thermal motion of charged particles in matter. All matter with a temperature greater than absolute zero emits thermal radiation....
.
Energy from radiation can move into a window in the day time, and out of the same window at night. Radiation uses photon
Photon
In physics, a photon is an elementary particle, the quantum of the electromagnetic interaction and the basic unit of light and all other forms of electromagnetic radiation. It is also the force carrier for the electromagnetic force...
s to transmit electromagnetic waves through a vacuum, or translucent medium. Solar heat gain can be significant even on cold clear days. Solar heat gain through windows can be reduced by insulated glazing
Insulated glazing
Insulated glazing also known as double glazing are double or triple glass window panes separated by an air or other gas filled space to reduce heat transfer across a part of the building envelope....
, shading, and orientation. Windows are particularly difficult to insulate compared to roof and walls. Convective heat transfer
Convective heat transfer
Convective heat transfer, often referred to as convection, is the transfer of heat from one place to another by the movement of fluids. The presence of bulk motion of the fluid enhances the heat transfer between the solid surface and the fluid. Convection is usually the dominant form of heat...
through and around window covering
Window covering
Window coverings are material used to cover a window to manage sunlight, to provide additional weatherproofing, to ensure privacy or for purely decorative purposes....
s also degrade its insulation properties. When shading windows, external shading is more effective at reducing heat gain than internal window covering
Window covering
Window coverings are material used to cover a window to manage sunlight, to provide additional weatherproofing, to ensure privacy or for purely decorative purposes....
s.
Western and eastern sun can provide warmth and lighting, but are vulnerable to overheating in summer if not shaded. In contrast, the low midday sun readily admits light and warmth during the winter, but can be easily shaded with appropriate length overhangs or angled louvres during summer. The amount of radiant heat received is related to the location latitude
Latitude
In geography, the latitude of a location on the Earth is the angular distance of that location south or north of the Equator. The latitude is an angle, and is usually measured in degrees . The equator has a latitude of 0°, the North pole has a latitude of 90° north , and the South pole has a...
, altitude
Altitude
Altitude or height is defined based on the context in which it is used . As a general definition, altitude is a distance measurement, usually in the vertical or "up" direction, between a reference datum and a point or object. The reference datum also often varies according to the context...
, cloud cover
Cloud cover
Cloud cover refers to the fraction of the sky obscured by clouds when observed from a particular location...
, and seasonal / hourly angle of incidence
Angle of incidence
Angle of incidence is a measure of deviation of something from "straight on", for example:* in the approach of a ray to a surface, or* the angle at which the wing or horizontal tail of an airplane is installed on the fuselage, measured relative to the axis of the fuselage.-Optics:In geometric...
(see Sun path
Sun path
Sun path refers to the apparent significant seasonal-and-hourly positional changes of the sun as the Earth rotates, and orbits around the sun. The relative position of the sun is a major factor in the heat gain of buildings and in the performance of solar energy systems...
and Lambert's cosine law
Lambert's cosine law
In optics, Lambert's cosine law says that the radiant intensity observed from a Lambertian surface or a Lambertian radiator is directly proportional to the cosine of the angle θ between the observer's line of sight and the surface normal. A Lambertian surface is also known as an ideal diffusely...
).
Another passive solar design principle is that thermal energy can be stored
Thermal mass
Thermal mass is a concept in building design which describes how the mass of the building provides "inertia" against temperature fluctuations, sometimes known as the thermal flywheel effect...
in certain building materials and released again when heat gain eases to stabilize diurnal
Diurnal temperature variation
Diurnal temperature variation is a meteorological term that relates to the variation in temperature that occurs from the highs of the day to the cool of nights.-Temperature lag:Temperature lag is an important factor in diurnal temperature variation...
(day/night) temperature variations. The complex interaction of thermodynamic principles can be counterintuitive
Counterintuitive
The word "counterintuitive" literally means counter to intuition, and so it essentially means that something does not seem right or correct.A counterintuitive proposition is one that does not seem likely to be true when assessed using intuition or gut feelings...
for first-time designers. Precise computer modeling
Building Information Modeling
Building information modeling is the process of generating and managing building data during its life cycle.BIM involves representing a design as objects – vague and undefined, generic or product-specific, solid shapes or void-space oriented , that carry their geometry, relations and attributes...
can help avoid costly construction experiments.
Site specific considerations during design
- LatitudeLatitudeIn geography, the latitude of a location on the Earth is the angular distance of that location south or north of the Equator. The latitude is an angle, and is usually measured in degrees . The equator has a latitude of 0°, the North pole has a latitude of 90° north , and the South pole has a...
, sun pathSun pathSun path refers to the apparent significant seasonal-and-hourly positional changes of the sun as the Earth rotates, and orbits around the sun. The relative position of the sun is a major factor in the heat gain of buildings and in the performance of solar energy systems...
, and insolationInsolationInsolation is a measure of solar radiation energy received on a given surface area in a given time. It is commonly expressed as average irradiance in watts per square meter or kilowatt-hours per square meter per day...
(sunshine) - Seasonal variations in solar gain e.g. cooling or heating degree dayHeating degree dayHeating degree day is a measurement designed to reflect the demand for energy needed to heat a home or business. It is derived from measurements of outside air temperature. The heating requirements for a given structure at a specific location are considered to be directly proportional to the...
s, solar insolationInsolationInsolation is a measure of solar radiation energy received on a given surface area in a given time. It is commonly expressed as average irradiance in watts per square meter or kilowatt-hours per square meter per day...
, humidityHumidityHumidity is a term for the amount of water vapor in the air, and can refer to any one of several measurements of humidity. Formally, humid air is not "moist air" but a mixture of water vapor and other constituents of air, and humidity is defined in terms of the water content of this mixture,... - DiurnalDiurnal temperature variationDiurnal temperature variation is a meteorological term that relates to the variation in temperature that occurs from the highs of the day to the cool of nights.-Temperature lag:Temperature lag is an important factor in diurnal temperature variation...
variations in temperature - Micro-climate details related to breezes, humidity, vegetation and land contour
- Obstructions / Over-shadowing - to solar gain or local cross-winds
Design elements for residential buildings in temperate climates
- Placement of room-types, internal doors & walls, & equipment in the house.
- Orienting the building to face the equator (or a few degrees to the East to capture the morning sun)
- Extending the building dimension along the east/west axis
- Adequately sizing windows to face the midday sun in the winter, and be shaded in the summer.
- Minimising windows on other sides, especially western windows
- Erecting correctly sized, latitude-specific roof overhangs, or shading elements (shrubbery, trees, trellises, fences, shutters, etc.)
- Using the appropriate amount and type of insulationBuilding insulationbuilding insulation refers broadly to any object in a building used as insulation for any purpose. While the majority of insulation in buildings is for thermal purposes, the term also applies to acoustic insulation, fire insulation, and impact insulation...
including radiant barriers and bulk insulation to minimise seasonal excessive heat gain or loss - Using thermal massThermal massThermal mass is a concept in building design which describes how the mass of the building provides "inertia" against temperature fluctuations, sometimes known as the thermal flywheel effect...
to store excess solar energy during the winter day (which is then re-radiated during the night)
The precise amount of equator-facing glass and thermal mass should be based on careful consideration of latitude, altitude, climatic conditions, and heating/cooling degree day
Degree day
A degree day is a measure of heating or cooling. Totalized degree days from an appropriate starting date are used to plan the planting of crops and management of pests and pest control timing...
requirements.
Factors that can degrade thermal performance:
- Deviation from ideal orientation and north/south/east/west aspect ratio
- Excessive glass area ('over-glazing') resulting in overheating (also resulting in glare and fading of soft furnishings) and heat loss when ambient air temperatures fall
- Installing glazing where solar gain during the day and thermal losses during the night cannot be controlled easily e.g. West-facing, angled glazing, skylights
- Thermal losses through non-insulated or unprotected glazing
- Lack of adequate shading during seasonal periods of high solar gain (especially on the West wall)
- Incorrect application of thermal massThermal massThermal mass is a concept in building design which describes how the mass of the building provides "inertia" against temperature fluctuations, sometimes known as the thermal flywheel effect...
to modulate daily temperature variations - Open staircases leading to unequal distribution of warm air between upper and lower floors as warm air rises
- High building surface area to volume - Too many corners
- Inadequate weatherizationWeatherizationWeatherization or weatherproofing is the practice of protecting a building and its interior from the elements, particularly from sunlight, precipitation, and wind, and of modifying a building to reduce energy consumption and optimize energy efficiency.Weatherization is distinct from building...
leading to high air infiltration - Lack of, or incorrectly installed, radiant barrierRadiant barrierRadiant barriers or reflective barriers inhibit heat transfer by thermal radiation. Thermal energy may also be transferred via conduction or convection, however, and radiant barriers do not necessarily protect against heat transfer via conduction or convection....
s during the hot season. (See also cool roofCool roofCool roofs are the roofs that can deliver high solar reflectance and high thermal emittance...
and green roofGreen roofA green roof is a roof of a building that is partially or completely covered with vegetation and a growing medium, planted over a waterproofing membrane. It may also include additional layers such as a root barrier and drainage and irrigation systems...
) - Insulation materialsBuilding insulationbuilding insulation refers broadly to any object in a building used as insulation for any purpose. While the majority of insulation in buildings is for thermal purposes, the term also applies to acoustic insulation, fire insulation, and impact insulation...
that are not matched to the main mode of heat transfer (e.g. undesirable convective/conductive/radiant heat transferHeat transferHeat transfer is a discipline of thermal engineering that concerns the exchange of thermal energy from one physical system to another. Heat transfer is classified into various mechanisms, such as heat conduction, convection, thermal radiation, and phase-change transfer...
)
Efficiency and economics of passive solar heating
Technically, PSH is highly efficient. Direct-gain systems can utilize (i.e. convert into "useful" heat) 65-70% of the energy of solar radiation that strikes the aperture or collector. To put this in perspective relative to another energy conversion process, the photosynthetic efficiencyPhotosynthetic efficiency
The photosynthetic efficiency is the fraction of light energy converted into chemical energy during photosynthesis in plants and algae. Photosynthesis can be described by the simplified chemical reactionwhere CH2O represents carbohydrates such as sugars, cellulose, and lignin.The value of the...
theoretical limit is around 11%.
Passive solar fraction (PSF) is the percentage of the required heat load met by PSH and hence represents potential reduction in heating costs. RETScreen International has reported a PSF of 20-50%. Within the field of sustainability
Sustainability
Sustainability is the capacity to endure. For humans, sustainability is the long-term maintenance of well being, which has environmental, economic, and social dimensions, and encompasses the concept of union, an interdependent relationship and mutual responsible position with all living and non...
, energy conservation even of the order of 15% is considered substantial.
Other sources report the following PSFs:
- 5-25% for modest systems
- 40% for "highly optimized" systems
- Up to 75% for "very intense" systems
In favorable climates such as the southwest United States, highly optimized systems can exceed 75% PSF.
Key passive solar building design concepts
There are six primary passive solar energy configurations:- direct solar gainSolar gainSolar gain refers to the increase in temperature in a space, object or structure that results from solar radiation...
- indirect solar gain
- isolated solar gain
- heat storage
- insulation and glazing
- passive coolingPassive coolingPassive cooling refers to technologies or design features used to cool buildings without power consumption, such as those technologies discussed in the Passive house project.-Passive cooling:...
Direct solar gain
Direct gain attempts to control the amount of direct solar radiation reaching the living space. This direct solar gain is a critical part of passive solar house designation as it imparts to a direct gain.The cost effectiveness of these configurations are currently being investigated in great detail and are demonstrating promising results.
Indirect solar gain
Indirect gain attempts to control solar radiation reaching an area adjacent but not part of the living space. Heat enters the building through windows and is captured and stored in thermal massThermal mass
Thermal mass is a concept in building design which describes how the mass of the building provides "inertia" against temperature fluctuations, sometimes known as the thermal flywheel effect...
(e.g. water tank, masonry wall) and slowly transmitted indirectly to the building through conduction and convection
Convection
Convection is the movement of molecules within fluids and rheids. It cannot take place in solids, since neither bulk current flows nor significant diffusion can take place in solids....
.
Efficiency can suffer from slow response (thermal lag) and heat losses at night. Other issues include the cost of insulated glazing
Insulated glazing
Insulated glazing also known as double glazing are double or triple glass window panes separated by an air or other gas filled space to reduce heat transfer across a part of the building envelope....
and developing effective systems to redistribute heat throughout the living area.
Isolated solar gain
Isolated gain involves utilizing solar energy to passively move heat from or to the living space using a fluid, such as water or air by natural convection or forced convectionConvection
Convection is the movement of molecules within fluids and rheids. It cannot take place in solids, since neither bulk current flows nor significant diffusion can take place in solids....
. Heat gain can occur through a sunspace, solarium or solar closet. These areas may also be employed usefully as a greenhouse or drying cabinet. An equator-side sun room may have its exterior windows higher than the windows between the sun room and the interior living space, to allow the low winter sun to penetrate to the cold side of adjacent rooms. Glass placement and overhangs prevent solar gain during the summer. Earth cooling tubes
Earth cooling tubes
A ground-coupled heat exchanger is an underground heat exchanger loop that can capture or dissipate heat to or from the ground. They use the Earth's near constant subterranean temperature to warm or cool air or other fluids for residential, agricultural or industrial uses...
or other passive cooling
Passive cooling
Passive cooling refers to technologies or design features used to cool buildings without power consumption, such as those technologies discussed in the Passive house project.-Passive cooling:...
techniques can keep a solarium cool in the summer.
Measures should be taken to reduce heat loss at night e.g. window coverings or movable window insulation
Examples:
- ThermosiphonThermosiphonThermosiphon refers to a method of passive heat exchange based on natural convection which circulates liquid without the necessity of a mechanical pump...
- Barra systemBarra systemThe Barra system is a passive solar building technology developed by Horazio Barra in Italy. It uses a collector wall to capture solar radiation in the form of heat. It also uses the thermosiphon effect to distribute the warmed air through channels incorporated into the reinforced concrete floors,...
- Double envelope houseDouble envelope house-History:Lee Porter Butler's 1975 Double Envelope design received wide publicity after the U.S. solar energy tax credits were created in 1978. Versions were on the cover of Better Homes and Gardens and Popular Science magazines....
- Thermal buffer zone
- Solar space heating system
- Solar chimneySolar chimneyA solar chimney — often referred to as a thermal chimney — is a way of improving the natural ventilation of buildings by using convection of air heated by passive solar energy...
Heat storage
The sun doesn't shine all the time. Heat storage, or thermal massThermal mass
Thermal mass is a concept in building design which describes how the mass of the building provides "inertia" against temperature fluctuations, sometimes known as the thermal flywheel effect...
keeps the building warm when the sun can't heat it.
In diurnal solar houses, the storage is designed for one or a few days. The usual method is a custom-constructed thermal mass. These include a Trombe wall
Trombe wall
A Trombe wall is a sun-facing wall separated from the outdoors by glass and an air space, which absorbs solar energy and releases it selectively towards the interior at night. The essential idea was first explored by Edward S. Morse and patented by him in 1881...
, a ventilated concrete floor, a cistern, water wall or roof pond.
In subarctic areas, or areas that have long terms without solar gain (e.g. weeks of freezing fog), purpose-built thermal mass is very expensive. Don Stephens pioneered an experimental technique to use the ground as thermal mass large enough for annualized heat storage. His designs run an isolated thermosiphon 3m under a house, and insulate the ground with a 6m waterproof skirt.
Insulation
Thermal insulationThermal insulation
Thermal insulation is the reduction of the effects of the various processes of heat transfer between objects in thermal contact or in range of radiative influence. Heat transfer is the transfer of thermal energy between objects of differing temperature...
or superinsulation
Superinsulation
Superinsulation is an approach to building design, construction, and retrofitting that dramatically reduces heat loss by using much higher levels of insulation and airtightness than normal...
(type, placement and amount) reduces unwanted leakage of heat. Some passive buildings are actually constructed of insulation.
Special glazing systems and window coverings
The effectiveness of direct solar gainSolar gain
Solar gain refers to the increase in temperature in a space, object or structure that results from solar radiation...
systems is significantly enhanced by insulative (e.g. double glazing), spectrally selective glazing (low-e
Low-emissivity
Low emissivity - actually low thermal emissivity - is a quality of a surface that radiates, or emits, low levels of radiant thermal energy. All materials absorb, reflect and emit radiant energy...
), or movable window insulation (window quilts, bifold interior insulation shutters, shades, etc.).
Generally, Equator-facing windows should not employ glazing coatings that inhibit solar gain.
There is extensive use of super-insulated windows in the German
Germany
Germany , officially the Federal Republic of Germany , is a federal parliamentary republic in Europe. The country consists of 16 states while the capital and largest city is Berlin. Germany covers an area of 357,021 km2 and has a largely temperate seasonal climate...
Passive House
Passive house
The term passive house refers to the rigorous, voluntary, Passivhaus standard for energy efficiency in a building, reducing its ecological footprint. It results in ultra-low energy buildings that require little energy for space heating or cooling. A similar standard, MINERGIE-P, is used in...
standard. Selection of different spectrally selective window coating depends on the ratio of heating versus cooling degree day
Degree day
A degree day is a measure of heating or cooling. Totalized degree days from an appropriate starting date are used to plan the planting of crops and management of pests and pest control timing...
s for the design location.
Equator-facing glass
The requirement for vertical equator-facing glass is different from the other three sides of a building. Reflective window coatingsInsulated glazing
Insulated glazing also known as double glazing are double or triple glass window panes separated by an air or other gas filled space to reduce heat transfer across a part of the building envelope....
and multiple panes of glass can reduce useful solar gain. However, direct-gain systems are more dependent on double or triple glazing
Insulated glazing
Insulated glazing also known as double glazing are double or triple glass window panes separated by an air or other gas filled space to reduce heat transfer across a part of the building envelope....
to reduce heat loss. Indirect-gain and isolated-gain configurations may still be able to function effectively with only single-pane glazing. Nevertheless, the optimal cost-effective solution is both location and system dependent.
Roof-angle glass / Skylights
Skylights admit harsh direct overhead sunlight and glare either horizontally (a flat roof) or pitched at the same angle as the roof slope. In some cases, horizontal skylights are used with reflectors to increase the intensity of solar radiation (and harsh glare), depending on the roof angle of incidenceAngle of incidence
Angle of incidence is a measure of deviation of something from "straight on", for example:* in the approach of a ray to a surface, or* the angle at which the wing or horizontal tail of an airplane is installed on the fuselage, measured relative to the axis of the fuselage.-Optics:In geometric...
. When the winter sun is low on the horizon, most solar radiation reflects off of roof angled glass ( the angle of incidence
Angle of incidence
Angle of incidence is a measure of deviation of something from "straight on", for example:* in the approach of a ray to a surface, or* the angle at which the wing or horizontal tail of an airplane is installed on the fuselage, measured relative to the axis of the fuselage.-Optics:In geometric...
is nearly parallel to roof-angled glass morning and afternoon ). When the summer sun is high, it is nearly perpendicular to roof-angled glass, which maximizes solar gain at the wrong time of year, and acts like a solar furnace. Skylights should be covered and well-insulated to reduce natural convection
Natural convection
Natural convection is a mechanism, or type of heat transport, in which the fluid motion is not generated by any external source but only by density differences in the fluid occurring due to temperature gradients. In natural convection, fluid surrounding a heat source receives heat, becomes less...
( warm air rising ) heat loss on cold winter nights, and intense solar heat gain during hot spring/summer/fall days.
The equator-facing side of a building is south in the northern hemisphere, and north in the southern hemisphere. Skylights on roofs that face away from the equator provide mostly-indirect illumination, except for summer days when the sun rises on the non-equator side of the building (depending on latitude
Latitude
In geography, the latitude of a location on the Earth is the angular distance of that location south or north of the Equator. The latitude is an angle, and is usually measured in degrees . The equator has a latitude of 0°, the North pole has a latitude of 90° north , and the South pole has a...
). Skylights on east-facing roofs provide maximum direct light and solar heat gain in the summer morning. West-facing skylights provide afternoon sunlight and heat gain during the hottest part of the day.
Some skylights have expensive glazing that partially reduces summer solar heat gain, while still allowing some visible light transmission. However, if visible light can pass through it, so can some radiant heat gain (they are both electromagnetic radiation
Electromagnetic radiation
Electromagnetic radiation is a form of energy that exhibits wave-like behavior as it travels through space...
waves.
You can partially reduce some of the unwanted roof-angled-glazing summer solar heat gain by installing a skylight in the shade of deciduous
Deciduous
Deciduous means "falling off at maturity" or "tending to fall off", and is typically used in reference to trees or shrubs that lose their leaves seasonally, and to the shedding of other plant structures such as petals after flowering or fruit when ripe...
(leaf-shedding) trees, or by adding a movable insulated opaque window covering on the inside or outside of the skylight. This would eliminate the daylight benefit in the summer. If tree limbs hang over a roof, they will increase problems with leaves in rain gutters, possibly cause roof-damaging ice dams, shorten roof life, and provide an easier path for pests to enter your attic. Leaves and twigs on skylights are unappealing, difficult to clean, and can increase the glazing breakage risk in wind storms.
"Sawtooth roof glazing" with vertical-glass-only can bring some of the passive solar building design benefits into the core of a commercial or industrial building, without the need for any roof-angled glass or skylights.
Skylights provide daylight. The only view they provide is essentially straight up in most applications. Well-insulated light tube
Light tube
Light tubes or light pipes are used for transporting or distributing natural or artificial light. In their application to daylighting, they are also often called sun pipes, sun scopes, solar light pipes, sky lights or daylight pipes.Generally speaking, a light pipe or light tube may refer to:* a...
s can bring daylight into northern rooms, without using a skylight. A passive-solar greenhouse provides abundant daylight for the equator-side of the building.
Infrared thermography
Thermography
Infrared thermography, thermal imaging, and thermal video are examples of infrared imaging science. Thermal imaging cameras detect radiation in the infrared range of the electromagnetic spectrum and produce images of that radiation, called thermograms...
color thermal imaging cameras ( used in formal energy audit
Energy audit
An energy audit is an inspection, survey and analysis of energy flows for energy conservation in a building, process or system to reduce the amount of energy input into the system without negatively affecting the output.-Principle:...
s ) can quickly document the negative thermal impact of roof-angled glass or a skylight on a cold winter night or hot summer day.
The U.S. Department of Energy states: "vertical glazing is the overall best option for sunspaces." Roof-angled glass and sidewall glass are not recommended for passive solar sunspaces.
The U.S. DOE explains drawbacks to roof-angled glazing: Glass and plastic have little structural strength. When installed vertically, glass (or plastic) bears its own weight because only a small area (the top edge of the glazing) is subject to gravity. As the glass tilts off the vertical axis, however, an increased area (now the sloped cross-section) of the glazing has to bear the force of gravity. Glass is also brittle; it does not flex much before breaking. To counteract this, you usually must increase the thickness of the glazing or increase the number of structural supports to hold the glazing. Both increase overall cost, and the latter will reduce the amount of solar gain into the sunspace.
Another common problem with sloped glazing is its increased exposure to the weather. It is difficult to maintain a good seal on roof-angled glass in intense sunlight. Hail, sleet, snow, and wind may cause material failure. For occupant safety, regulatory agencies usually require sloped glass to be made of safety glass, laminated, or a combination thereof, which reduce solar gain potential. Most of the roof-angled glass on the Crowne Plaza Hotel Orlando Airport sunspace was destroyed in a single windstorm. Roof-angled glass increases construction cost, and can increase insurance premiums. Vertical glass is less susceptible to weather damage than roof-angled glass.
It is difficult to control solar heat gain in a sunspace with sloped glazing during the summer and even during the middle of a mild and sunny winter day. Skylights are the antithesis of zero energy building
Zero energy building
A zero-energy building, also known as a zero net energy building, Net-Zero Energy Building , or Net Zero Building, is a popular term to describe a building with zero net energy consumption and zero carbon emissions annually. Zero energy buildings can be independent from the energy grid supply...
Passive Solar Cooling in climates with an air conditioning requirement.
Angle of incident radiation
The amount of solar gain transmitted through glass is also affected by the angle of the incident solar radiation. SunlightSunlight
Sunlight, in the broad sense, is the total frequency spectrum of electromagnetic radiation given off by the Sun. On Earth, sunlight is filtered through the Earth's atmosphere, and solar radiation is obvious as daylight when the Sun is above the horizon.When the direct solar radiation is not blocked...
striking glass within 20 degrees of perpendicular
Perpendicular
In geometry, two lines or planes are considered perpendicular to each other if they form congruent adjacent angles . The term may be used as a noun or adjective...
is mostly transmitted through the glass, whereas sunlight at more than 35 degrees from perpendicular is mostly reflected
All of these factors can be modeled more precisely with a photographic light meter
Light meter
A light meter is a device used to measure the amount of light. In photography, a light meter is often used to determine the proper exposure for a photograph...
and a heliodon
Heliodon
A heliodon is a device for adjusting the angle between a flat surface and a beam of light to match the angle between a horizontal plane at a specific latitude and the solar beam. Heliodons are used primarily by architects and students of architecture...
or optical bench, which can quantify the ratio of reflectivity
Reflectivity
In optics and photometry, reflectivity is the fraction of incident radiation reflected by a surface. In general it must be treated as a directional property that is a function of the reflected direction, the incident direction, and the incident wavelength...
to transmissivity
Transmittance
In optics and spectroscopy, transmittance is the fraction of incident light at a specified wavelength that passes through a sample. A related term is absorptance, or absorption factor, which is the fraction of radiation absorbed by a sample at a specified wavelength...
, based on angle of incidence
Angle of incidence
Angle of incidence is a measure of deviation of something from "straight on", for example:* in the approach of a ray to a surface, or* the angle at which the wing or horizontal tail of an airplane is installed on the fuselage, measured relative to the axis of the fuselage.-Optics:In geometric...
.
Alternatively, passive solar computer software can determine the impact of sun path
Sun path
Sun path refers to the apparent significant seasonal-and-hourly positional changes of the sun as the Earth rotates, and orbits around the sun. The relative position of the sun is a major factor in the heat gain of buildings and in the performance of solar energy systems...
, and cooling-and-heating degree day
Degree day
A degree day is a measure of heating or cooling. Totalized degree days from an appropriate starting date are used to plan the planting of crops and management of pests and pest control timing...
s on energy
Energy
In physics, energy is an indirectly observed quantity. It is often understood as the ability a physical system has to do work on other physical systems...
performance. Regional climatic conditions are often available from local weather services.
Operable shading and insulation devices
A design with too much equator-facing glass can result in excessive winter, spring, or fall day heating, uncomfortably bright living spaces at certain times of the year, and excessive heat transfer on winter nights and summer days.Although the sun is at the same altitude 6-weeks before and after the solstice, the heating and cooling requirements before and after the solstice are significantly different. Heat storage on the Earth's surface causes "thermal lag." Variable cloud cover influences solar gain potential. This means that latitude-specific fixed window overhangs, while important, are not a complete seasonal solar gain control solution.
Control mechanisms (such as manual-or-motorized interior insulated drapes, shutters, exterior roll-down shade screens, or retractable awnings) can compensate for differences caused by thermal lag or cloud cover, and help control daily / hourly solar gain requirement variations.
Home automation
Home automation
Home automation is the residential extension of "building automation". It is automation of the home, housework or household activity. Home automation may include centralized control of lighting, HVAC , appliances, and other systems, to provide improved convenience, comfort, energy efficiency and...
systems that monitor temperature, sunlight, time of day, and room occupancy can precisely control motorized window-shading-and-insulation devices.
Exterior colors reflecting - absorbing
Materials and colors can be chosen to reflect or absorb solar thermal energySolar thermal energy
Solar thermal energy is a technology for harnessing solar energy for thermal energy . Solar thermal collectors are classified by the United States Energy Information Administration as low-, medium-, or high-temperature collectors. Low-temperature collectors are flat plates generally used to heat...
. Using information on a Color
Color
Color or colour is the visual perceptual property corresponding in humans to the categories called red, green, blue and others. Color derives from the spectrum of light interacting in the eye with the spectral sensitivities of the light receptors...
for electromagnetic radiation
Electromagnetic radiation
Electromagnetic radiation is a form of energy that exhibits wave-like behavior as it travels through space...
to determine its thermal radiation
Thermal radiation
Thermal radiation is electromagnetic radiation generated by the thermal motion of charged particles in matter. All matter with a temperature greater than absolute zero emits thermal radiation....
properties of reflection or absorption can assist the choices.
See Lawrence Berkeley National Laboratory and Oak Ridge National Laboratory: "Cool Colors"
Landscaping and gardens
Energy-efficient landscapingEnergy-efficient landscaping
Energy-efficient landscaping is a type of landscaping designed for the purpose of conserving energy. There is a distinction between the embedded energy of materials and constructing the landscape, and the energy consumed by the maintenance and operations of a landscape.Design techniques include:*...
materials for careful passive solar choices include hardscape
Hardscape
Hardscape, in the practice of landscaping, refers to the paved areas like streets & sidewalks, large business complexes & housing developments, and other industrial areas where the upper soil profile is no longer exposed to the actual surface of the Earth...
building material and "softscape
Softscape
Softscape refers to the elements of a landscape that comprise live, horticultural elements. Softscaping can include, flowers, plants, shrubs, trees, flower beds, etc. This is a term that has been popularized in recent pop culture on television shows such as Home & Garden Television...
" plant
Plant
Plants are living organisms belonging to the kingdom Plantae. Precise definitions of the kingdom vary, but as the term is used here, plants include familiar organisms such as trees, flowers, herbs, bushes, grasses, vines, ferns, mosses, and green algae. The group is also called green plants or...
s. The use of landscape design
Landscape design
Landscape design is an independent profession and a design and art tradition, practised by landscape designers, combining nature and culture. In contemporary practice landscape design bridges between landscape architecture and garden design.-Design scope:...
principles for selection of trees, hedges, and trellis
Trellis (agriculture)
A trellis is an architectural structure, usually made from interwoven pieces of wood, bamboo or metal that is often made to support climbing plants...
-pergola
Pergola
A pergola, arbor or arbour is a garden feature forming a shaded walkway, passageway or sitting area of vertical posts or pillars that usually support cross-beams and a sturdy open lattice, often upon which woody vines are trained...
features with vine
Vine
A vine in the narrowest sense is the grapevine , but more generally it can refer to any plant with a growth habit of trailing or scandent, that is to say climbing, stems or runners...
s; all can be used to create summer shading. For winter solar gain it is desirable to use deciduous
Deciduous
Deciduous means "falling off at maturity" or "tending to fall off", and is typically used in reference to trees or shrubs that lose their leaves seasonally, and to the shedding of other plant structures such as petals after flowering or fruit when ripe...
plants that drop their leaves in the autumn gives year round passive solar benefits. Non-deciduous evergreen
Evergreen
In botany, an evergreen plant is a plant that has leaves in all seasons. This contrasts with deciduous plants, which completely lose their foliage during the winter or dry season.There are many different kinds of evergreen plants, both trees and shrubs...
shrub
Shrub
A shrub or bush is distinguished from a tree by its multiple stems and shorter height, usually under 5–6 m tall. A large number of plants may become either shrubs or trees, depending on the growing conditions they experience...
s and trees can be windbreak
Windbreak
A windbreak or shelterbelt is a plantation usually made up of one or more rows of trees or shrubs planted in such a manner as to provide shelter from the wind and to protect soil from erosion. They are commonly planted around the edges of fields on farms. If designed properly, windbreaks around a...
s, at variable heights and distances, to create protection and shelter from winter wind chill
Wind chill
Wind chill is the felt air temperature on exposed skin due to wind. The wind chill temperature is always lower than the air temperature, and the windchill is undefined at the higher temps...
. Xeriscaping
Xeriscaping
Xeriscaping and xerogardening refers to landscaping and gardening in ways that reduce or eliminate the need for supplemental water from irrigation...
with 'mature size appropriate' native species
Native plant
Native plant is a term to describe plants endemic or naturalized to a given area in geologic time.This includes plants that have developed, occur naturally, or existed for many years in an area...
of-and drought tolerant plants
Drought tolerance
Drought tolerance refers to the degree to which a plant is adapted to arid or drought conditions. Desiccation tolerance is an extreme degree of drought tolerance...
, drip irrigation
Drip irrigation
Drip irrigation, also known as trickle irrigation or microirrigation or localized irrigation , is an irrigation method which saves water and fertilizer by allowing water to drip slowly to the roots of plants, either onto the soil surface or directly onto the root zone, through a network of valves,...
, mulching, and organic gardening practices reduce or eliminate the need for energy-and-water-intensive irrigation
Irrigation
Irrigation may be defined as the science of artificial application of water to the land or soil. It is used to assist in the growing of agricultural crops, maintenance of landscapes, and revegetation of disturbed soils in dry areas and during periods of inadequate rainfall...
, gas powered garden equipment, and reduces the landfill waste footprint. Solar powered landscape lighting and fountain pumps, and covered swimming pool
Swimming pool
A swimming pool, swimming bath, wading pool, or simply a pool, is a container filled with water intended for swimming or water-based recreation. There are many standard sizes; the largest is the Olympic-size swimming pool...
s and plunge pool
Plunge pool
A plunge pool can be a natural hydrologic fluvial landform feature or a constructed recreational garden feature...
s with solar water heaters
Solar water heating
Solar water heating or solar hot water systems comprise several innovations and many mature renewable energy technologies that have been well established for many years...
can reduce the impact of such amenities.
- Sustainable gardeningSustainable gardeningSustainable gardening comprises a disparate group of horticultural interests that share, to a greater or lesser extent, the aims and objectives associated with the international post-1980s sustainable development and sustainability programs...
- Sustainable landscapingSustainable landscapingSustainable landscaping encompasses a variety of practices that have developed in response to environmental issues. These practices are used in every phase of landscaping, including design, construction, implementation and management of residential and commercial landscapes. Issues of...
- Sustainable landscape architectureSustainable landscape architectureSustainable landscape architecture is a category of sustainable design concerned with the planning and design of outdoor space.This can include ecological, social and economic aspects of sustainability...
Passive solar lighting
Passive solar lighting techniques enhance taking advantage of naturalSunlight
Sunlight, in the broad sense, is the total frequency spectrum of electromagnetic radiation given off by the Sun. On Earth, sunlight is filtered through the Earth's atmosphere, and solar radiation is obvious as daylight when the Sun is above the horizon.When the direct solar radiation is not blocked...
illumination
Daylighting
Daylighting is the practice of placing windows or other openings and reflective surfaces so that during the day natural light provides effective internal lighting. Particular attention is given to daylighting while designing a building when the aim is to maximize visual comfort or to reduce energy...
for interiors, and so reduce reliance on artificial lighting systems.
This can be achieved by careful building design, orientation, and placement of window sections to collect light. Other creative solutions involve the use of reflecting surfaces to admit daylight into the interior of a building. Window sections should be adequately sized, and to avoid over-illumination
Over-illumination
Over-illumination is the presence of lighting intensity beyond that required for a specified activity. Over-illumination was commonly ignored between 1950 and 1995, especially in office and retail environments; only since then has the interior design community begun to reconsider this practice.The...
can be shielded with a Brise soleil
Brise soleil
Brise soleil, sometimes brise-soleil , from French, "sun breaker"), in architecture refers to a variety of permanent sun-shading techniques, ranging from the simple patterned concrete walls popularized by Le Corbusier to the elaborate wing-like mechanism devised by Santiago Calatrava for the...
, awning
Awning
An awning or overhang is a secondary covering attached to the exterior wall of a building. It is typically composed of canvas woven of acrylic, cotton or polyester yarn, or vinyl laminated to polyester fabric that is stretched tightly over a light structure of aluminium, iron or steel, possibly...
s, well placed trees, glass coatings, and other passive and active devices.
Another major issue for many window
Window
A window is a transparent or translucent opening in a wall or door that allows the passage of light and, if not closed or sealed, air and sound. Windows are usually glazed or covered in some other transparent or translucent material like float glass. Windows are held in place by frames, which...
systems is that they can be potentially vulnerable sites of excessive thermal gain or heat loss. Whilst high mounted clerestory
Clerestory
Clerestory is an architectural term that historically denoted an upper level of a Roman basilica or of the nave of a Romanesque or Gothic church, the walls of which rise above the rooflines of the lower aisles and are pierced with windows. In modern usage, clerestory refers to any high windows...
window and traditional skylights can introduce daylight in poorly oriented sections of a building, unwanted heat transfer may be hard to control. Thus, energy that is saved by reducing artificial lighting is often more than offset by the energy required for operating HVAC
HVAC
HVAC refers to technology of indoor or automotive environmental comfort. HVAC system design is a major subdiscipline of mechanical engineering, based on the principles of thermodynamics, fluid mechanics, and heat transfer...
systems to maintain thermal comfort
Thermal comfort
Thermal comfort is a term used by the American Society of Heating, Refrigerating and Air-Conditioning Engineers, an international body. It is defined as the state of mind in humans that expresses satisfaction with the surrounding environment...
.
Various methods can be employed to address this including but not limited to window covering
Window covering
Window coverings are material used to cover a window to manage sunlight, to provide additional weatherproofing, to ensure privacy or for purely decorative purposes....
s, insulated glazing
Insulated glazing
Insulated glazing also known as double glazing are double or triple glass window panes separated by an air or other gas filled space to reduce heat transfer across a part of the building envelope....
and novel materials such as aerogel
Aerogel
Aerogel is a synthetic porous material derived from a gel, in which the liquid component of the gel has been replaced with a gas. The result is a solid with extremely low density and thermal conductivity...
semi-transparent insulation, optical fiber
Optical fiber
An optical fiber is a flexible, transparent fiber made of a pure glass not much wider than a human hair. It functions as a waveguide, or "light pipe", to transmit light between the two ends of the fiber. The field of applied science and engineering concerned with the design and application of...
embedded in walls or roof, or hybrid solar lighting at Oak Ridge National Laboratory.
Interior reflecting
Reflecting elements, from active and passive daylightingPassive Daylighting
Passive daylighting is a system of both: collecting sunlight using static, non-moving, and non-tracking systems such as Windows, Sliding glass doors, most skylights, light tubes, and reflecting the collected daylight deeper inside with elements such as light shelves...
collectors, such as light shelves, lighter wall and floor colors, mirror
Mirror
A mirror is an object that reflects light or sound in a way that preserves much of its original quality prior to its contact with the mirror. Some mirrors also filter out some wavelengths, while preserving other wavelengths in the reflection...
ed wall sections, interior walls with upper glass panels, and clear or translucent glassed hinged door
Door
A door is a movable structure used to open and close off an entrance, typically consisting of a panel that swings on hinges or that slides or rotates inside of a space....
s and sliding glass doors take the captured light and passively reflect it further inside. The light can be from passive windows or skylights and solar light tube
Light tube
Light tubes or light pipes are used for transporting or distributing natural or artificial light. In their application to daylighting, they are also often called sun pipes, sun scopes, solar light pipes, sky lights or daylight pipes.Generally speaking, a light pipe or light tube may refer to:* a...
s or from active daylighting
Active Daylighting
Active daylighting is a system of collecting sunlight using a mechanical device to increase the efficiency of light collection for a given lighting purpose...
sources. In traditional Japanese architecture
Japanese architecture
' originated in prehistoric times with simple pit-houses and stores that were adapted to a hunter-gatherer population. Influence from Han Dynasty China via Korea saw the introduction of more complex grain stores and ceremonial burial chambers....
the Shōji
Shoji
In traditional Japanese architecture, a shōji is a door, window or room divider consisting of translucent paper over a frame of wood which holds together a lattice of wood or bamboo...
sliding panel doors, with translucent Washi
Washi
is a type of paper made in Japan. Washi is commonly made using fibers from the bark of the gampi tree, the mitsumata shrub , or the paper mulberry, but also can be made using bamboo, hemp, rice, and wheat...
screens, are an original precedent. International style
International style (architecture)
The International style is a major architectural style that emerged in the 1920s and 1930s, the formative decades of Modern architecture. The term originated from the name of a book by Henry-Russell Hitchcock and Philip Johnson, The International Style...
, Modernist
Modern architecture
Modern architecture is generally characterized by simplification of form and creation of ornament from the structure and theme of the building. It is a term applied to an overarching movement, with its exact definition and scope varying widely...
and Mid-century modern
Mid-century modern
Mid-Century modern is an architectural, interior and product design form that generally describes mid-20th century developments in modern design, architecture, and urban development from roughly 1933 to 1965...
architecture
Architecture
Architecture is both the process and product of planning, designing and construction. Architectural works, in the material form of buildings, are often perceived as cultural and political symbols and as works of art...
were earlier innovators of this passive penetration and reflection in industrial, commercial, and residential applications.
Passive solar water heating
There are many ways to use solar thermal energySolar thermal energy
Solar thermal energy is a technology for harnessing solar energy for thermal energy . Solar thermal collectors are classified by the United States Energy Information Administration as low-, medium-, or high-temperature collectors. Low-temperature collectors are flat plates generally used to heat...
to heat water for domestic use. Different active-and-passive solar hot water
Solar hot water
Solar water heating or solar hot water systems comprise several innovations and many mature renewable energy technologies that have been well established for many years...
technologies have different location-specific economic cost benefit analysis implications.
Fundamental passive solar hot water heating involves no pumps or anything electrical. It is very cost effective in climates that do not have lengthy sub-freezing, or very-cloudy, weather conditions. Other active solar water heating technologies, etc. may be more appropriate for some locations.
It is possible to have active solar hot water which is also capable of being "off grid" and qualifies as sustainable. This is done by the use of a photovoltaic cell which uses energy from the sun to power the pumps.
Comparison to the Passive House standard in Europe
There is growing momentum in Europe for the approach espoused by the Passive HousePassive house
The term passive house refers to the rigorous, voluntary, Passivhaus standard for energy efficiency in a building, reducing its ecological footprint. It results in ultra-low energy buildings that require little energy for space heating or cooling. A similar standard, MINERGIE-P, is used in...
(Passivhaus in German) Institute in Germany. Rather than relying solely on traditional passive solar design techniques, this approach seeks to make use of all passive sources of heat, minimises energy usage, and emphasises the need for high levels of insulation reinforced by meticulous attention to detail in order to address thermal bridging and cold air infiltration. Most of the buildings built to the Passive House standard also incorporate an active heat recovery ventilation
Heat recovery ventilation
Heat recovery ventilation, also known as HRV, mechanical ventilation heat recovery, or MVHR, is an energy recovery ventilation system using equipment known as a heat recovery ventilator, heat exchanger, air exchanger, or air-to-air heat exchanger which employs a counter-flow heat exchanger between...
unit with or without a small (typically 1 kW) incorporated heating component.
The energy design of Passive House buildings is developed using a spreadsheet-based modeling tool called the Passive House Planning Package (PHPP) which is updated periodically. The current version is PHPP2007, where 2007 is the year of issue. A building may be certified as a 'Passive House' when it can be shown that it meets certain criteria, the most important being that the annual specific heat demand for the house should not exceed 15kWh/m2a.
Design tools
Traditionally a heliodonHeliodon
A heliodon is a device for adjusting the angle between a flat surface and a beam of light to match the angle between a horizontal plane at a specific latitude and the solar beam. Heliodons are used primarily by architects and students of architecture...
was used to simulate the altitude and azimuth of the sun shining on a model building at any time of any day of the year. In modern times, computer programs can model this phenomenon and integrate local climate data (including site impacts such as overshadowing
Shadow
A shadow is an area where direct light from a light source cannot reach due to obstruction by an object. It occupies all of the space behind an opaque object with light in front of it. The cross section of a shadow is a two-dimensional silhouette, or reverse projection of the object blocking the...
and physical obstructions) to predict the solar gain potential for a particular building design over the course of a year. GPS-based smartphone
Smartphone
A smartphone is a high-end mobile phone built on a mobile computing platform, with more advanced computing ability and connectivity than a contemporary feature phone. The first smartphones were devices that mainly combined the functions of a personal digital assistant and a mobile phone or camera...
applications can now do this inexpensively on a hand held device. These tools provide the passive solar designer the ability to evaluate local conditions, design elements and orientation prior to construction. Energy performance optimization normally requires an iterative-refinement design-and-evaluate process. There is no such thing as a "one-size-fits-all" universal passive solar building design that would work well in all locations.
Pragmatic
Many detached suburban houses can achieve reductions in heating expense without obvious changes to their appearance, comfort or usability. This is done using good siting and window positioning, small amounts of thermal mass, with good-but-conventional insulation, weatherization, and an occasional supplementary heat source, such as a central radiator connected to a (solar) water heater. Sunrays may fall on a wall during the daytime and raise the temperature of its thermal massThermal mass
Thermal mass is a concept in building design which describes how the mass of the building provides "inertia" against temperature fluctuations, sometimes known as the thermal flywheel effect...
. This will then radiate
Thermal radiation
Thermal radiation is electromagnetic radiation generated by the thermal motion of charged particles in matter. All matter with a temperature greater than absolute zero emits thermal radiation....
heat into the building in the evening. This can be a problem in the summer, especially on western walls in areas with high degree day cooling requirements. External shading, or a radiant barrier plus air gap, may be used to reduce undesirable summer solar gain.
Annualised
An extension of the "passive solar" approach to seasonal solar capture and storage of heat and cooling. These designs attempt to capture warm-season solar heat, and convey it to a seasonal thermal storeSeasonal thermal store
A seasonal thermal store is a store designed to retain heat deposited during the hot summer months for use during colder winter weather...
for use months later during the cold season ("annualised passive solar.") Increased storage is achieved by employing large amounts of thermal mass or earth coupling. Anecdotal reports suggest they can be effective but no formal study has been conducted to demonstrate their superiority.
The approach also can move cooling into the warm season.
Examples:
- Passive Annual Heat Storage (PAHS) - by John Hait
- Annualized Geothermal Solar (AGS) heating - by Don Stephen
- Earthed-roofEarth shelteringEarth sheltering is the architectural practice of using earth against building walls for external thermal mass, to reduce heat loss, and to easily maintain a steady indoor air temperature...
Minimum machinery
A "purely passive" solar-heated house would have no mechanical furnace unit, relying instead on energy captured from sunshine, only supplemented by "incidental" heat energy given off by lights, computers, and other task-specific appliances (such as those for cooking, entertainment, etc.), showering, people and pets. The use of natural convection air currents (rather than mechanical devices such as fans) to circulate air is related, though not strictly solar design.Passive solar building design sometimes uses limited electrical and mechanical controls to operate dampers, insulating shutters, shades, awnings, or reflectors. Some systems enlist small fans or solar-heated chimneys to improve convective air-flow. A reasonable way to analyse these systems is by measuring their coefficient of performance. A heat pump might use 1 J for every 4 J it delivers giving a COP of 4. A system that only uses a 30 W fan to more-evenly distribute 10 kW of solar heat through an entire house would have a COP of 300.
Zero Energy Building
Passive solar building design is often a foundational element of a cost-effective zero energy buildingZero energy building
A zero-energy building, also known as a zero net energy building, Net-Zero Energy Building , or Net Zero Building, is a popular term to describe a building with zero net energy consumption and zero carbon emissions annually. Zero energy buildings can be independent from the energy grid supply...
. Although a ZEB uses multiple passive solar building design concepts, a ZEB is usually not purely passive, having active mechanical renewable energy generation systems such as: wind turbine
Wind turbine
A wind turbine is a device that converts kinetic energy from the wind into mechanical energy. If the mechanical energy is used to produce electricity, the device may be called a wind generator or wind charger. If the mechanical energy is used to drive machinery, such as for grinding grain or...
, photovoltaics
Photovoltaics
Photovoltaics is a method of generating electrical power by converting solar radiation into direct current electricity using semiconductors that exhibit the photovoltaic effect. Photovoltaic power generation employs solar panels composed of a number of solar cells containing a photovoltaic material...
, micro hydro
Micro hydro
Micro hydro is a term used for hydroelectric power installations that typically produce up to 100 kW of electricity. These installations can provide power to an isolated home or small community, or are sometimes connected to electric power networks....
, geothermal
Geothermal
Geothermal is related to energy and may refer to:* The geothermal gradient and associated heat flows from within the Earth- Renewable technology :...
, and other emerging alternative energy sources.
See also
- Active daylightingActive DaylightingActive daylighting is a system of collecting sunlight using a mechanical device to increase the efficiency of light collection for a given lighting purpose...
- Active solarActive solarActive solar technologies are employed to convert solar energy into another more useful form of energy. This would normally be a conversion to heat or electrical energy. Inside a building this energy would be used for heating, cooling, or off-setting other energy use or costs. Active solar uses...
- Architecture 2030Architecture 2030Architecture 2030 is a U.S. based, non-traditional and flexible environmental advocacy group focused on protecting the global environment by using innovation and common sense to develop, and quickly implement, bold solutions to global warming. The organization was founded by Edward Mazria in 2003...
- DaylightingDaylightingDaylighting is the practice of placing windows or other openings and reflective surfaces so that during the day natural light provides effective internal lighting. Particular attention is given to daylighting while designing a building when the aim is to maximize visual comfort or to reduce energy...
- Energy plus house
- List of low-energy building techniques
- Low energy building
- Low-energy houseLow-energy houseA low-energy house is any type of house that from design, technologies and building products uses less energy, from any source, than a traditional or average contemporary house...
- PlusEnergyPlusEnergyPlusEnergy is a coined concept developed by Rolf Disch that indicates a structure’s extreme energy efficiency so that it holds a positive energy balance, actually producing more energy than it uses. With the completion of his private residence, the Heliotrope, in 1994, Disch had created the first...
- The 2010 ImperativeThe 2010 ImperativeThe 2010 Imperative is an initiative issued by Architecture 2030 that requires ecological literacy, largely missing from the curriculum in the United States, to become a key element of design education by 2010, in order to combat global warming and world resource depletion.-The initiative:The 2010...
- Zero energy buildingZero energy buildingA zero-energy building, also known as a zero net energy building, Net-Zero Energy Building , or Net Zero Building, is a popular term to describe a building with zero net energy consumption and zero carbon emissions annually. Zero energy buildings can be independent from the energy grid supply...
- Zero energy design (Process)
Energy Rating systems
- House Energy RatingHouse Energy RatingA House Energy Rating is an index of a building's thermal performance for residential homes in Australia....
(Aust.) - Home energy ratingHome energy ratingA Home Energy Rating is a measurement of a home’s energy efficiency, used primarily in the United States. Home energy ratings can be used for either existing homes or new homes. A home energy rating of an existing home allows a homeowner to receive a report listing options for upgrading a home’s...
(USA) - EnerGuideEnerGuideEnerGuide is the official Government of Canada mark associated with the labelling and rating of the energy consumption or energy efficiency of specific products...
(Canada) - National Home Energy RatingNational Home Energy RatingThe National Home Energy Rating Scheme is both a UK accreditation scheme for energy assessors and a rating scale for the energy efficiency of housing.The NHER is owned and operated by National Energy Services...
(UK)
Solar-designers
- History of passive solar building designHistory of passive solar building design-Pre-modern History:The techniques of passive solar building design were practiced for thousands of years, by necessity, before the advent of mechanical heating and cooling. It has remained a traditional part of vernacular architecture in many countries...
- :Category:Solar building designers
- List of pioneering solar buildings
- Rolf DischRolf DischRolf Disch is a German architect, solar energy pioneer and environmental activist who has contributed greatly to the advancement and efficiency of solar architecture internationally...
, Rolf Disch Solar ArchitectureRolf Disch Solar ArchitectureRolf Disch Solar Architecture, creators of the Heliotrope as well as several other visionary green building projects, is based in the solar city Freiburg, Germany. Led by solar pioneer Rolf Disch, who has been building with the sun for more than 40 years, this architecture office's prolific... - Steve BaerSteve BaerSteve Baer is an American inventor and solar and residential designer. Baer has served on the board of directors of the U.S. Section of the International Solar Energy Society, and on the board of the New Mexico Solar Energy Association. He is the Founder, Chairman of the Board, President, and...
- J. BaldwinJ. BaldwinJames Tennant Baldwin is an American industrial designer and writer...
- Tom BenderTom BenderTom Bender is one of the American founders of the "green architecture" and "sustainability" movements.-Life:He began to make his mark in the early 1970s as an architect, author, and strategic planner. He has since been visible also as a writer in the emerging field of green economics...
- Lee Porter Butler
- Peter CalthorpePeter CalthorpePeter Calthorpe is a San Francisco-based architect, urban designer and urban planner. He is a founding member of the Congress for New Urbanism, a Chicago-based advocacy group formed in 1992 that promotes sustainable building practices.-Biography:...
- Buckminster FullerBuckminster FullerRichard Buckminster “Bucky” Fuller was an American systems theorist, author, designer, inventor, futurist and second president of Mensa International, the high IQ society....
- Larry Hartweg - DOE/ORNL Zero Energy Design® http://www.ZeroEnergyDesign.com
- William McDonoughWilliam McDonoughWilliam Andrews McDonough is an American architect, founding principal of , co-founder of with German chemist Michael Braungart as well as co-author of also with Braungart...
- William Shurcliff
- Felix TrombeFélix TrombeFelix Trombe was a French engineer.He is best known for his pioneering work in passive solar building design with the Trombe wall, which bears his name.- Mont-Louis Solar Furnace :...
- Sim Van der RynSim Van der RynSim Van der Ryn is acknowledged as a leader in "sustainable architecture." He is also a researcher and educator. Van der Ryn's driving professional interest has been applying principles of physical and social ecology to architecture and environmental design....
- James WinesJames WinesJames Wines is an American artist/architect associated with environmental design.Wines is also an architectural and design innovator, a product designer, and an educator...
- Ken YeangKen YeangDr. Ken Yeang [Chinese]: 杨经文/楊經文; [pinyin]: Yáng Jīngwén; born 1948) is a prolific Malaysian architect and writer best known for advancing green design and planning, differentiated from other green architects by his comprehensive ecological approach....
External links
- Passive Solar Design Techniques
- www.solarbuildings.ca - Canadian Solar Buildings Research Network
- www.greenbuilder.com - Passive Solar Design
- Direct space heating and daylighting with heliostats (photos)
- www.eere.energy.gov - US Department of Energy (DOE) Guidelines
- www.climatechange.gov.au - Australian Dept of Climate Change and Energy Efficiency
- www.ornl.gov - Oak Ridge National Laboratory (ORNL) Building Technology
- www.FSEC.UCF.edu - Florida Solar Energy Center
- www.ZeroEnergyDesign.com - 28 Years of Passive Solar Building Design
- Passive Solar Design Guidelines
- http://www.solaroof.org/wiki
- Calculation of insolation (houses, garden, roof, apartment...)
- www.PassiveSolarEnergy.info - Passive Solar Energy Technology Overview
- www.gaisma.com- Sun path calculator for selected cites
- http://sunposition.info/sunposition/spc/locations.php - Sun path by location and date
- www.yourhome.gov.au/technical/index.html - Your Home Technical Manual developed by the Commonwealth of Australia to provide information about how to design, build and live in environmentally sustainable homes.
- amergin.tippinst.ie/downloadsEnergyArchhtml.html- Energy in Architecture, The European Passive Solar Handbook, Goulding J.R, Owen Lewis J, Steemers Theo C, Sponsored by the European Commission, published by Batsford 1986, reprinted 1993
- www.viking-house.ie High standard in Passive solar design Co. Cork Ireland
- www.solaraspects.com - website that provides advice on maximizing the solar passive design potential for new homes
- Passive Solar House Plans - info website, explaining the concept of passive solar houses