Thermal comfort
Encyclopedia
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 (ANSI/ASHRAE Standard 55). Maintaining this standard of thermal comfort for occupants of buildings or other enclosures is one of the important goals of HVAC
(heating, ventilation, and air conditioning) design engineers.
Thermal comfort is affected by heat conduction
, convection
, radiation
, and evaporative heat loss. Thermal comfort is maintained when the heat generated by human metabolism
is allowed to dissipate, thus maintaining thermal equilibrium with the surroundings. It has been long recognised that the sensation of feeling hot or cold is not just dependent on air temperature alone.
symptoms.
The combination of high temperature and high relative humidity serves to reduce thermal comfort and indoor air quality. . The occurrence of symptoms increased much more with raised indoor temperatures in the winter than in the summer due to the larger difference created between indoor and outdoor temperatures.
Food and drink habits may have an influence on metabolic rates, which indirectly influences thermal preferences. These effects may change depending on food and drink intake.
Body Shape is another factor that affects thermal comfort. Heat dissipation depends on body surface area. A tall and skinny person has a larger surface-to-volume ratio, can dissipate heat more easily, and can tolerate higher temperatures than a more rounded body shape.
The amount of clothing is measured against a standard amount that is roughly equivalent to a typical business suit, shirt, and undergarments. Activity level is compared to being seated quietly, such as in a classroom. This standard amount of insulation required to keep a resting person warm in a windless room at 70 °F (21.1 °C) is equal to one clo.
Clo units can be converted to R-value
in SI units (m²·K/W) or RSI) by multiplying clo by 0.155 (1 clo = 0.155 RSI). (In English units 1 clo corresponds to an R-value of 0.88 °F·ft²·h/Btu.)
ASHRAE 55-2004 mentioned a Table B1 and Table B2 for more clothing information.
A way to measure the amount of relative humidity in the air is to use a system of dry-bulb and wet-bulb thermometers. A dry-bulb thermometer measures the temperature not relative to moisture. This is generally the temperature reading that is used in weather reports. In contrast, a wet-bulb thermometer has a small wet cloth wrapped around the bulb at its base, so the reading on that thermometer takes into account water evaporation in the air. The wet-bulb reading will thus always be at least slightly lower than the dry bulb reading. The difference between these two temperatures can be used to calculate the relative humidity. The larger the temperature difference between the two thermometers, the lower the level of relative humidity.
The wettedness of skin in different areas also affects perceived thermal comfort. Humidity can increase wetness on different areas of the body, leading to a perception of discomfort. This is usually localized in different parts of the body and local thermal comfort limits for local skin wettedness differ between different skin locations of the body. The extremities are much more sensitive to thermal discomfort from wetness than the trunk of the body. Although local thermal discomfort can be caused from wetness, the thermal comfort of the whole body will not be affected by the wetness of certain parts[12].
Recently, the effects of low relative humidity and high air velocity were tested on humans after bathing. Researchers found that low relative humidity engendered thermal discomfort as well as the sensation of dryness and itching. It is recommended to keep relative humidity levels higher in a bathroom than other rooms in the house for optimal conditions.
for military personnel undergoing training exercises or athletes during competitive events. Values are expressed as the Wet Bulb Globe Temperature or Discomfort Index.
Generally, humans do not perform well under thermal stress. People’s performances under thermal stress is about 11% lower than their performance at normal thermal conditions. Also, human performance in relation to thermal stress varies greatly by the type of task you are completing. Some of the physiological effects of thermal heat stress include increased blood flow to the skin, sweating, and increased ventilation.
If there is an imbalance despite the vasomotor adjustments listed above, in a warm environment sweat production will start and an evaporative cooling mechanism will be provided. If this is insufficient, hyperthermia will set in, body temperature may reach 40∘C and heat stroke may occur. In a cold environment shivering will start, involuntarily forcing the muscles to work and increasing the heat production by up to a factor of 10. If equilibrium is not restored, hypothermia will set in which, can be fatal.
Long term adjustments to extreme temperatures of a few days to 6 months may result in cardiovascular and endocrine adjustments. A hot climate may create increased blood volume, improving the effectiveness of vasodilation, enhanced performance of the sweat mechanism, and the readjustment of thermal preferences. In cold or underheated conditions, vasoconstriction can become permanent resulting in decreased blood volume, and increased body metabolic rate.
to deal with the less than ideal temperatures.
. This is the average of the air dry-bulb temperature and of the mean radiant temperature
at the given place in a room. In addition, there should be low air velocities and no 'drafts,' little variation in the radiant temperatures from different directions in the room, and humidity within a comfortable range.
The operative temperature intervals varied by the type of indoor location. They also vary by the time of year. ASHRAE has listings for suggested temperatures and air flow rates in different types of buildings and different environmental circumstances. For example, a single office in a building has an occupancy ration per square meter of 0.1. In the summer the suggested temperature is between 23.5 (74.3 F) and 25.5 degrees Celsius (77.9 F) , and airflow velocity of 0.18 m/s. In the winter, the recommended temperature is between 21.0 and 23.0 degrees Celsius with an airflow velocity of 0.15 m/s.
Situational factors include the health, psychological, sociological and vocational activities of the persons.
Many times, females will prefer higher temperatures. But while females were more sensitive to temperatures, males tend to be more sensitive to relative humidity levels.
The adaptive model states that there is an optimal temperature for a given indoor environment depending on the outdoor air temperature. It takes into account that humans can adapt and tolerate different temperatures during different times of the year. The optimal temperature for a given time is determined by looking at the mean outdoor temperatures of each month of the year. Also, field studies are performed in these areas to see what the majority of people would prefer as their set-point temperature indoors at different times of the year.
On the other side, the static model states that the indoor temperature should not change as the seasons do. Rather, there should be one set temperature year-round. This is taking a more passive stand that humans do not have to adapt to different temperatures since it will always be constant.
More advanced research on thermal comfort considers the heat balance of the human body and calculates sensation and comfort for local body parts.
In tropical areas of Brazil, urbanization is causing a phenomenon called urban heat island
s (UHI). These are urban areas, which have risen over the thermal comfort limits due to a large influx of people and only drop within the comfortable range during the rainy season. Urban Heat Islands can occur over any urban city or built up area with the correct conditions. Urban Heat Islands are caused by urban areas with few trees and vegetation to block solar radiation or carry out evapotranspiration, many structures with a large proportion of roofs and sidewalks with low reflectivity that absorb heat, high amounts of ground-level carbon dioxide pollution that retains heat released by surfaces, great amounts of heat generated by air conditioning systems of densely packed buildings and large amount of automobile traffic generating heat from engines and exhaust..
In the hot humid region of Saudi Arabia
, the issue of thermal comfort has been important in mosques where Muslims (followers of Islam
, the only religion allowed to operate publicly in Saudi Arabia, according to the Shariah) go to pray
. They are very large open buildings which are used only intermittently (very busy for the obligatory
noon prayer
on Fridays) making it hard to ventilate them properly. The large size requires a large amount of ventilation but this requires a lot of energy since the buildings are used only for short periods of time. Some mosques have the issue of being too cold from their HVAC systems running for too long and others remain too hot. The stack effect also comes into play due to their large size and creates a large layer of hot air above the people in the mosque. New designs have placed the ventilation systems lower in the buildings to provide more temperature control at ground level. Also new monitoring steps are being taken to improve the efficiency..
by Ole Fanger
and others. Perceived comfort was found to be a complex interaction of these variables. It was found that the majority of individuals would be satisfied by an ideal set of values. As the range of values deviated progressively from the ideal, fewer and fewer people were satisfied. This observation could be expressed statistically as the % of individual who expressed satisfaction by comfort conditions and the predicted mean vote (PMV)
This research is applied to create Building Energy Simulation (BES) programs for residential buildings. Residential buildings can vary much more in thermal comfort than public and commercial buildings. This is due to their smaller size, the variations in clothing worn, and different uses of each room. The main rooms of concern are bathrooms and bedrooms. Bathrooms need to be at a temperature comfortable for a human with or without clothing. Bedrooms are of importance because they need to accommodate different levels of clothing and also different metabolic rates of people asleep or awake.
Thermal comfort research in clothing is currently being done by the military. New air-ventilated garments are being researched to improve evaporative cooling in military settings. Some models are being created and tested based on the amount of cooling they provide.
American Society of Heating, Refrigerating and Air-Conditioning Engineers
The American Society of Heating, Refrigerating and Air Conditioning Engineers is an international technical society for all individuals and organizations interested in heating, ventilation, air-conditioning, and refrigeration...
, an international body. It is defined as the state of mind in humans that expresses satisfaction with the surrounding environment (ANSI/ASHRAE Standard 55). Maintaining this standard of thermal comfort for occupants of buildings or other enclosures is one of the important goals of 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...
(heating, ventilation, and air conditioning) design engineers.
Thermal comfort is affected by heat 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....
, 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....
, 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....
, and evaporative heat loss. Thermal comfort is maintained when the heat generated by human metabolism
Metabolism
Metabolism is the set of chemical reactions that happen in the cells of living organisms to sustain life. These processes allow organisms to grow and reproduce, maintain their structures, and respond to their environments. Metabolism is usually divided into two categories...
is allowed to dissipate, thus maintaining thermal equilibrium with the surroundings. It has been long recognised that the sensation of feeling hot or cold is not just dependent on air temperature alone.
Importance of thermal comfort
Thermal discomfort has been known to lead to Sick Building SyndromeSick building syndrome
Sick building syndrome is a combination of ailments associated with an individual's place of work or residence. A 1984 World Health Organization report into the syndrome suggested up to 30% of new and remodeled buildings worldwide may be linked to symptoms of SBS...
symptoms.
The combination of high temperature and high relative humidity serves to reduce thermal comfort and indoor air quality. . The occurrence of symptoms increased much more with raised indoor temperatures in the winter than in the summer due to the larger difference created between indoor and outdoor temperatures.
Factors determining thermal comfort
Factors determining thermal comfort include:- Personal factors (health, psychology, sociology & situational factors)
- Insulative clothing (Clo Value)
- Activity levels (Met Rate)
- General Factors
- Air temperature
- Mean radiant temperatureMean radiant temperatureThe 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...
- Relative humidityRelative humidityRelative 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...
(see also perspiration) - Drifts and ramps in operative temperatureOperative temperatureOperative temperature is defined as a uniform temperature of a radiantly black enclosure in which an occupant would exchange the same amount of heat by radiation plus convection as in the actual nonuniform environment. Some references also use the terms 'equivalent temperature" or 'effective...
- Localized factors
- Air movement/velocity (see wind chill factor)
- Radiant asymmetry
- Floor surface temperatures (see underfloor heatingUnderfloor heatingUnderfloor heating and cooling is a form of central heating and cooling which achieves indoor climate control for thermal comfort using conduction, radiation and convection...
) - Air temperature stratification
Metabolism
When measuring metabolic rates, many factors have to be taken into account. Each person has a different metabolic rate, and these rates can fluctuate when a person is performing certain activities, or under certain environmental conditions. Even people who are in the same room can feel significant temperature differences due to their metabolic rates, which makes it very hard to find an optimal temperature for everyone in a given location.Food and drink habits may have an influence on metabolic rates, which indirectly influences thermal preferences. These effects may change depending on food and drink intake.
Body Shape is another factor that affects thermal comfort. Heat dissipation depends on body surface area. A tall and skinny person has a larger surface-to-volume ratio, can dissipate heat more easily, and can tolerate higher temperatures than a more rounded body shape.
Clothing insulation
During cold weather, layers of insulating clothing can help keep a person warm. At the same time, if the person is doing a large amount of physical activity, lots of clothing layers can prevent heat loss and possibly lead to overheating. Generally, the thicker the garment is the greater insulating abilities it has. Depending on the type of material the clothing is made out of, air movement and relative humidity can decrease the insulating ability of the material.The amount of clothing is measured against a standard amount that is roughly equivalent to a typical business suit, shirt, and undergarments. Activity level is compared to being seated quietly, such as in a classroom. This standard amount of insulation required to keep a resting person warm in a windless room at 70 °F (21.1 °C) is equal to one clo.
Clo units can be converted to R-value
R-value (insulation)
The R-value is a measure of thermal resistance used in the building and construction industry. Under uniform conditions it is the ratio of the temperature difference across an insulator and the heat flux through it or R = \Delta T/\dot Q_A.The R-value being discussed is the unit thermal resistance...
in SI units (m²·K/W) or RSI) by multiplying clo by 0.155 (1 clo = 0.155 RSI). (In English units 1 clo corresponds to an R-value of 0.88 °F·ft²·h/Btu.)
ASHRAE 55-2004 mentioned a Table B1 and Table B2 for more clothing information.
Relative humidity
The human body has sensors that are fairly efficient in sensing heat and cold, but they are not very effective in detecting relative humidity. Relative humidity creates the perception of an extremely dry or extremely damp indoor environment. This can then play a part in the perceived temperature and their thermal comfort. The recommended level of indoor humidity is in the range of 30-60%.A way to measure the amount of relative humidity in the air is to use a system of dry-bulb and wet-bulb thermometers. A dry-bulb thermometer measures the temperature not relative to moisture. This is generally the temperature reading that is used in weather reports. In contrast, a wet-bulb thermometer has a small wet cloth wrapped around the bulb at its base, so the reading on that thermometer takes into account water evaporation in the air. The wet-bulb reading will thus always be at least slightly lower than the dry bulb reading. The difference between these two temperatures can be used to calculate the relative humidity. The larger the temperature difference between the two thermometers, the lower the level of relative humidity.
The wettedness of skin in different areas also affects perceived thermal comfort. Humidity can increase wetness on different areas of the body, leading to a perception of discomfort. This is usually localized in different parts of the body and local thermal comfort limits for local skin wettedness differ between different skin locations of the body. The extremities are much more sensitive to thermal discomfort from wetness than the trunk of the body. Although local thermal discomfort can be caused from wetness, the thermal comfort of the whole body will not be affected by the wetness of certain parts[12].
Recently, the effects of low relative humidity and high air velocity were tested on humans after bathing. Researchers found that low relative humidity engendered thermal discomfort as well as the sensation of dryness and itching. It is recommended to keep relative humidity levels higher in a bathroom than other rooms in the house for optimal conditions.
Thermal stress
The concept of thermal comfort is closely related to thermal stress. This attempts to predict the impact of solar radiation, air movement, and humidityHumidity
Humidity 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,...
for military personnel undergoing training exercises or athletes during competitive events. Values are expressed as the Wet Bulb Globe Temperature or Discomfort Index.
Generally, humans do not perform well under thermal stress. People’s performances under thermal stress is about 11% lower than their performance at normal thermal conditions. Also, human performance in relation to thermal stress varies greatly by the type of task you are completing. Some of the physiological effects of thermal heat stress include increased blood flow to the skin, sweating, and increased ventilation.
Adjustment mechanisms
The body has several thermal adjustment mechanisms to survive in drastic temperature environments. In a cold environment the body utilizes vasoconstriction; which reduces blood flow to the skin, skin temperature and heat dissipation. In a warm environment, vasodilation will increase blood flow to the skin, heat transport, and skin temperature and heat dissipation.If there is an imbalance despite the vasomotor adjustments listed above, in a warm environment sweat production will start and an evaporative cooling mechanism will be provided. If this is insufficient, hyperthermia will set in, body temperature may reach 40∘C and heat stroke may occur. In a cold environment shivering will start, involuntarily forcing the muscles to work and increasing the heat production by up to a factor of 10. If equilibrium is not restored, hypothermia will set in which, can be fatal.
Long term adjustments to extreme temperatures of a few days to 6 months may result in cardiovascular and endocrine adjustments. A hot climate may create increased blood volume, improving the effectiveness of vasodilation, enhanced performance of the sweat mechanism, and the readjustment of thermal preferences. In cold or underheated conditions, vasoconstriction can become permanent resulting in decreased blood volume, and increased body metabolic rate.
Effects of natural ventilation of thermal comfort
Many buildings use a HVAC (Heating Ventilation Air Conditioning) unit to control their thermal environment. Recently, with the current energy and financial situation, new methods for indoor temperature control are being used. One of these is natural ventilation. This process can make the controlled indoor air temperature more susceptible to the outdoor weather, and during the seasonal months the temperatures inside can become too extreme. During the summer months, the temperature inside can rise too high and cause the need for open windows and fans to be used. In contrast, the winter months could call for more insulation and layered clothingLayered clothing
Layered clothing is a manner of dressing using multiple garments that are worn on top of each other. Some of the layers have different, largely non-overlapping, functions. Using more or fewer layers, or replacing one layer but not others, allows for flexible clothing to match the needs of each...
to deal with the less than ideal temperatures.
Operative temperature
The ideal standard for thermal comfort can be defined by the operative temperatureOperative temperature
Operative temperature is defined as a uniform temperature of a radiantly black enclosure in which an occupant would exchange the same amount of heat by radiation plus convection as in the actual nonuniform environment. Some references also use the terms 'equivalent temperature" or 'effective...
. This is the average of the air dry-bulb temperature and of the 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...
at the given place in a room. In addition, there should be low air velocities and no 'drafts,' little variation in the radiant temperatures from different directions in the room, and humidity within a comfortable range.
The operative temperature intervals varied by the type of indoor location. They also vary by the time of year. ASHRAE has listings for suggested temperatures and air flow rates in different types of buildings and different environmental circumstances. For example, a single office in a building has an occupancy ration per square meter of 0.1. In the summer the suggested temperature is between 23.5 (74.3 F) and 25.5 degrees Celsius (77.9 F) , and airflow velocity of 0.18 m/s. In the winter, the recommended temperature is between 21.0 and 23.0 degrees Celsius with an airflow velocity of 0.15 m/s.
Thermal sensitivity of individuals
The thermal sensitivity of an individual is quantified by the descriptor FS, which takes on higher values for individuals with lower tolerance to non-ideal thermal conditions. This group includes pregnant women, the disabled, as well as individuals whose age is below 14 or above 60, which is considered the adult range. Existing literature provides consistent evidence that sensitivity to hot and cold surfaces declines with age. There is also some evidence of a gradual reduction in the effectiveness of the body in thermoregulation after the age of 60.. This is mainly due to a more sluggish response of the counteraction mechanisms in the body that are used to maintain the core temperature of the body at ideal values.Situational factors include the health, psychological, sociological and vocational activities of the persons.
Gender differences
While thermal comfort preferences between genders seems to be small, there are some differences. Studies have found men report discomfort due to rises in temperature much earlier than women. Men also estimate higher levels of their sensation of discomfort than women. One recent study tested men and women in the same cotton clothing, performing mental jobs while using a dial vote to report their thermal comfort to the changing temperature.Many times, females will prefer higher temperatures. But while females were more sensitive to temperatures, males tend to be more sensitive to relative humidity levels.
Models of thermal comfort
When discussing thermal comfort, there are two different models that can be used. These are the static model and the adaptive model.The adaptive model states that there is an optimal temperature for a given indoor environment depending on the outdoor air temperature. It takes into account that humans can adapt and tolerate different temperatures during different times of the year. The optimal temperature for a given time is determined by looking at the mean outdoor temperatures of each month of the year. Also, field studies are performed in these areas to see what the majority of people would prefer as their set-point temperature indoors at different times of the year.
On the other side, the static model states that the indoor temperature should not change as the seasons do. Rather, there should be one set temperature year-round. This is taking a more passive stand that humans do not have to adapt to different temperatures since it will always be constant.
More advanced research on thermal comfort considers the heat balance of the human body and calculates sensation and comfort for local body parts.
Thermal comfort in different regions
In different areas of the world, thermal comfort needs may vary based on climate. In China there are hot humid summers and cold winters causing a need for efficient thermal comfort. Energy conservation in relation to thermal comfort has become a large issue in China in the last several decades due to rapid economic and population growth. Researchers are now looking into ways to heat and cool buildings in China for lower costs and also with less harm to the environment.In tropical areas of Brazil, urbanization is causing a phenomenon called urban heat island
Urban heat island
An urban heat island is a metropolitan area which is significantly warmer than its surrounding rural areas. The phenomenon was first investigated and described by Luke Howard in the 1810s, although he was not the one to name the phenomenon. The temperature difference usually is larger at night...
s (UHI). These are urban areas, which have risen over the thermal comfort limits due to a large influx of people and only drop within the comfortable range during the rainy season. Urban Heat Islands can occur over any urban city or built up area with the correct conditions. Urban Heat Islands are caused by urban areas with few trees and vegetation to block solar radiation or carry out evapotranspiration, many structures with a large proportion of roofs and sidewalks with low reflectivity that absorb heat, high amounts of ground-level carbon dioxide pollution that retains heat released by surfaces, great amounts of heat generated by air conditioning systems of densely packed buildings and large amount of automobile traffic generating heat from engines and exhaust..
In the hot humid region of Saudi Arabia
Saudi Arabia
The Kingdom of Saudi Arabia , commonly known in British English as Saudi Arabia and in Arabic as as-Sa‘ūdiyyah , is the largest state in Western Asia by land area, constituting the bulk of the Arabian Peninsula, and the second-largest in the Arab World...
, the issue of thermal comfort has been important in mosques where Muslims (followers of Islam
Islam
Islam . The most common are and . : Arabic pronunciation varies regionally. The first vowel ranges from ~~. The second vowel ranges from ~~~...
, the only religion allowed to operate publicly in Saudi Arabia, according to the Shariah) go to pray
Pray
Pray may refer to:* Prayer, an active effort to communicate with a deity or spiritIt may also refer to:-Places:Italy* Pray, Piedmont, a comune in the Province of BiellaUnited States* Pray, Wisconsin, an unincorporated community-People:...
. They are very large open buildings which are used only intermittently (very busy for the obligatory
Fard
also is an Islamic term which denotes a religious duty. The word is also used in Persian, Turkish, and Urdu in the same meaning....
noon prayer
Jumu'ah
Jumu'ah is a congregational prayer that Muslims hold every Friday, just after noon in lieu of dhuhr...
on Fridays) making it hard to ventilate them properly. The large size requires a large amount of ventilation but this requires a lot of energy since the buildings are used only for short periods of time. Some mosques have the issue of being too cold from their HVAC systems running for too long and others remain too hot. The stack effect also comes into play due to their large size and creates a large layer of hot air above the people in the mosque. New designs have placed the ventilation systems lower in the buildings to provide more temperature control at ground level. Also new monitoring steps are being taken to improve the efficiency..
Thermal comfort of livestock
Although thermal comfort of humans is the main focus of thermal comfort studies, the needs of livestock must be met as well for better living and production. The Department of Animal Production in Italy produced a study on ewes, which tested rumen function and diet digestibility of ewes chronically exposed to a hot environment. These two bodily functions were reduced by the hot temperatures offering insight that thermal comfort levels are important to livestock productivity.Research
These factors were explored experimentally in the 1970s. Many of these studies led to the development and refinement of ASHRAE Standard 55 and were performed at Kansas State UniversityKansas State University
Kansas State University, commonly shortened to K-State, is an institution of higher learning located in Manhattan, Kansas, in the United States...
by Ole Fanger
P. Ole Fanger
Povl Ole Fanger was an expert in the field of the health effects of indoor environments. He was a University Professor at Syracuse University when he died at the age of 72 from an abdominal aortic aneurysm. He was also a senior professor at the International Centre for Indoor Environment and...
and others. Perceived comfort was found to be a complex interaction of these variables. It was found that the majority of individuals would be satisfied by an ideal set of values. As the range of values deviated progressively from the ideal, fewer and fewer people were satisfied. This observation could be expressed statistically as the % of individual who expressed satisfaction by comfort conditions and the predicted mean vote (PMV)
This research is applied to create Building Energy Simulation (BES) programs for residential buildings. Residential buildings can vary much more in thermal comfort than public and commercial buildings. This is due to their smaller size, the variations in clothing worn, and different uses of each room. The main rooms of concern are bathrooms and bedrooms. Bathrooms need to be at a temperature comfortable for a human with or without clothing. Bedrooms are of importance because they need to accommodate different levels of clothing and also different metabolic rates of people asleep or awake.
Thermal comfort research in clothing is currently being done by the military. New air-ventilated garments are being researched to improve evaporative cooling in military settings. Some models are being created and tested based on the amount of cooling they provide.
See also
- P. Ole FangerP. Ole FangerPovl Ole Fanger was an expert in the field of the health effects of indoor environments. He was a University Professor at Syracuse University when he died at the age of 72 from an abdominal aortic aneurysm. He was also a senior professor at the International Centre for Indoor Environment and...
- Room air distributionRoom air distributionCharacterizing how air is introduced to, flows through, and is removed from spaces is called room air distribution. HVAC airflow in spaces generally can be classified by two different types: mixing and displacement.-Mixing systems:...
- PsychrometricsPsychrometricsPsychrometrics 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...
- Air conditioningAir conditioningAn air conditioner is a home appliance, system, or mechanism designed to dehumidify and extract heat from an area. The cooling is done using a simple refrigeration cycle...
- Building 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...
- Mahoney tables