Life cycle assessment
Encyclopedia
A life-cycle assessment (LCA, also known as life-cycle analysis, ecobalance, and cradle-to-grave analysis) is a technique to assess environmental impacts associated with all the stages of a product's life from-cradle-to-grave (i.e., from raw material extraction through materials processing, manufacture, distribution, use, repair and maintenance, and disposal or recycling). LCA’s can help avoid a narrow outlook on environmental concerns by:
The term life cycle refers to the notion that a fair, holistic assessment requires the assessment of raw-material production, manufacture, distribution
, use and disposal including all intervening transportation steps necessary or caused by the product's existence.
There are two main types of LCA. Attributional LCAs seek to establish the burdens associated with the production and use of a product, or with a specific service or process, at a point in time (typically the recent past). Consequential LCAs seek to identify the environmental consequences of a decision or a proposed change in a system under study (oriented to the future), which means that market and economic implications of a decision may have to be taken into account. Social LCA is under development as a different approach to life cycle thinking intended to assess social implications or potential impacts. Social LCA should be considered as an approach that is complementary to environmental LCA.
The procedures of life cycle assessment (LCA) are part of the ISO 14000
environmental management standards: in ISO 14040:2006 and 14044:2006. (ISO 14044 replaced earlier versions of ISO 14041 to ISO 14043.)
According to the ISO 14040 and 14044 standards, a Life Cycle Assessment is carried out in four distinct phases as illustrated in the figure shown to the right.The phases are often interdependent in that the results of one phase will inform how other phases are completed.
The data must be related to the functional unit defined in the goal and scope definition. Data can be presented in tables and some interpretations can be made already at this stage. The results of the inventory is an LCI which provides information about all inputs and outputs in the form of elementary flow to and from the environment from all the unit processes involved in the study.
Inventory flows can number in the hundreds depending on the system boundary. For product LCAs at either the generic (i.e., representative industry averages) or brand-specific level, that data is typically collected through survey questionnaires. At an industry level, care has to be taken to ensure that questionnaires are completed by a representative sample of producers, leaning toward neither the best nor the worst, and fully representing any regional differences due to energy use, material sourcing or other factors. The questionnaires cover the full range of inputs and outputs, typically aiming to account for 99% of the mass of a product, 99% of the energy used in its production and any environmentally sensitive flows, even if they fall within the 1% level of inputs.
One area where data access is likely to be difficult is flows from the technosphere. Those completing a questionnaire will be able to specify how much of a given input they use from supply chain sources, but they will not usually have access to data concerning inputs and outputs for those production processes. The entity undertaking the LCA must then turn to secondary sources if it does not already have that data from its own previous studies. National databases or data sets that come with LCA-practitioner tools, or that can be readily accessed, are the usual sources for that information. Care must then be taken to ensure that the secondary data source properly reflects regional or national conditions.
In many LCAs, characterization concludes the LCIA analysis; this is also the last compulsory stage according to ISO 14044:2006. However, in addition to the above mandatory LCIA steps, other optional LCIA elements – normalization, grouping, and weighting – may be conducted depending on the goal and scope of the LCA study. In normalization, the results of the impact categories from the study are usually compared with the total impacts in the region of interest, the U.S. for example. Grouping consists of sorting and possibly ranking the impact categories. During weighting, the different environmental impacts are weighted relative to each other so that they can then be summed to get a single number for the total environmental impact. ISO 14044:2006 generally advises against weighting, stating that “weighting, shall not be used in LCA studies intended to be used in comparative assertions intended to be disclosed to the public”. This advice is often ignored, resulting in comparisons that can reflect a high degree of subjectivity as a result of weighting.
A key purpose of performing life cycle interpretation is to determine the level of confidence in the final results and communicate them in a fair, complete, and accurate manner. Interpreting the results of an LCA is not as simple as 3 is better than 2, therefore Alternative A is the best choice! Interpreting the results of an LCA starts with understanding the accuracy of the results, and ensuring they meet the goal of the study. This is accomplished by identifying the data elements that contribute significantly to each impact category, evaluating the sensitivity of these significant data elements, assessing the completeness and consistency of the study, and drawing conclusions and recommendations based on a clear understanding of how the LCA was conducted and the results were developed.
In the former category, the three principal tools are GaBi Software, developed by PE International, SimaPro, developed by PRé Consultants, and umberto, developed by ifu Hamburg GmbH. In the second category, different tools operate at different levels. At the product level, the U.S. National Institute of Standards and Technology (NIST) makes its BEES (Building for Environmental and Economic Sustainability) tool freely available and PTC’s Windchill Product Analytics makes LCA results an integral part of product development systems. At the whole building design level, different tools are available in different parts of the world. For example, the ATHENA® Impact Estimator for Buildings is capable of modeling 95% of the building stock in North America, Envest has been developed by the Building Research Establishment to meet UK needs, and EcoQuantum is available in the Netherlands. For the Netherlands, extensive databases (open access) are available on the so called eco-costs
and carbon footprint of buildings and its components, see winket. The European Council of Construction Economists is planning to develop such open source databases for other European countries as well. At a building assembly level (e.g., exterior walls) the free ATHENA® EcoCalculator for Assemblies is an example of a tool that serves North America and the Whole Building Design Guide is an example of a tool applicable to the UK.
Based on a survey of LCA practitioners carried out in 2006 LCA is mostly used to support business strategy (18%) and R&D (18%), as input to product or process design (15%), in education (13%) and for labeling or product declarations (11%).
Major corporations all over the world are either undertaking LCA in house or commissioning studies, while governments support the development of national databases to support LCA. Of particular note is the growing use of LCA for ISO Type III labels called Environmental Product Declarations, defined as "quantified environmental data for a product with pre-set categories of parameters based on the ISO 14040 series of standards, but not excluding additional environmental information". These third-party certified LCA-based labels provide an increasingly important basis for assessing the relative environmental merits of competing products.
; therefore, it is crucial that data used for the completion of a life cycle analysis is accurate and current. When comparing different life cycle analyses with one another, it is crucial that equivalent data is available for both products or processes in question. If one product has a much higher availability of data, it cannot be justly compared to another product which has less detailed data.
There are two basic types of LCA data – unit process data and environmental input-output data (EIO), where the latter is based on national economic input-output data. Unit process data is derived from direct surveys of companies or plants producing the product of interest, carried out at a unit process level defined by the system boundaries for the study.
Data validity is an ongoing concern for life cycle analyses. Due to globalization
and the rapid pace of research and development
, new materials and manufacturing methods are continually being introduced to the market. This makes it both very important and very difficult to use up-to-date information when performing an LCA. If an LCA’s conclusions are to be valid, the data must be recent; however, the data-gathering process takes time. If a product and its related processes have not undergone significant revisions since the last LCA data was collected, data validity is not a problem. However, consumer electronics
such as cell phones can be redesigned as often as every 9 to 12 months, creating a need for ongoing data collection.
The life cycle considered usually consists of a number of stages including: materials extraction, processing and manufacturing, product use, and product disposal. If the most environmentally harmful of these stages can be determined, then impact on the environment can be efficiently reduced by focusing on making changes for that particular phase. For example, the most energy-intensive life phase of an airplane or car is during use due to fuel consumption. One of the most effective ways to increase fuel efficiency is to decrease vehicle weight, and thus, car and airplane manufacturers can decrease environmental impact in a significant way by replacing aluminum with lighter materials such as carbon fiber reinforced fibers. The reduction during the use phase should be more than enough to balance additional raw material or manufacturing cost
.
(fiberised paper) insulation
, then used as an energy-saving device in the ceiling of a home for 40 years, saving 2,000 times the fossil-fuel
energy used in its production. After 40 years the cellulose
fibers are replaced and the old fibers are disposed of, possibly incinerated. All inputs and outputs are considered for all the phases of the life cycle.
process. It is a method used to minimize the environmental impact of products by employing sustainable production, operation, and disposal practices and aims to incorporate social responsibility into product development. From the recycling process originate new, identical products (e.g., asphalt pavement from discarded asphalt pavement, glass bottles from collected glass bottles), or different products (e.g., glass wool insulation from collected glass bottles).
Allocation of burden for products in open loop production systems presents considerable challenges for LCA. Various methods, such as the avoided burden
approach have been proposed to deal with the issues involved.
fuel
s and vehicles. The analysis is often broken down into stages entitled "well-to-station", or "well-to-tank", and "station-to-wheel" or "tank-to-wheel", or "plug-to-wheel". The first stage, which incorporates the feedstock or fuel production and processing and fuel delivery or energy transmission, and is called the "upstream" stage, while the stage that deals with vehicle operation itself is sometimes called the "downstream" stage. The well-to-wheel analysis is commonly used to assess total energy consumption, or energy conversion efficiency
and emission
s impact of marine vessels, aircraft
s and motor vehicle emissions
, including their carbon footprint
, and the fuels used in each of these transport modes.
The well-to-wheel variant has a significant input on a model developed by the Argonne National Laboratory
. The Greenhouse gases, Regulated Emissions, and Energy use in Transportation (GREET) model was developed to evaluate the impacts of new fuels and vehicle technologies. The model evaluates the impacts of fuel use using a well-to-wheel evaluation while a traditional cradle-to-grave approach is used to determine the impacts from the vehicle itself. The model reports energy use, greenhouse gas emissions, and six additional pollutants: volatile organic compounds (VOCs), carbon monoxide
(CO), nitrogen oxide
(NOx), particulate matter with size smaller than 10 micrometre (PM10), particulate matter with size smaller than 2.5 micrometre (PM2.5), and sulfur oxides (SOx).
) involves use of aggregate sector-level data on how much environmental impact can be attributed to each sector of the economy and how much each sector purchases from other sectors. Such analysis can account for long chains (for example, building an automobile requires energy, but producing energy requires vehicles, and building those vehicles requires energy, etc.), which somewhat alleviates the scoping problem of process LCA; however, EIOLCA relies on sector-level averages that may or may not be representative of the specific subset of the sector relevant to a particular product and therefore is not suitable for evaluating the environmental impacts of products. Additionally the translation of economic quantities into environmental impacts is not validated.
Developed by Ohio State University Center for resilience, Eco-LCA is a methodology that quantitatively takes into account regulating and supporting services during the life cycle of economic goods and products. In this approach services are categorized in four main groups: supporting, regulating provisioning and cultural services.
inputs to a product are accounted for, not only direct energy inputs during manufacture, but also all energy inputs needed to produce components, materials and services needed for the manufacturing process. An earlier term for the approach was energy analysis.
With LCEA, the total life cycle energy input is established.
commodities themselves, such as nuclear energy
, photovoltaic
electricity
or high-quality petroleum products. Net energy
content is the energy content of the product minus energy input used
during extraction and conversion
, directly or
indirectly.
A controversial early result of LCEA claimed that manufacturing
solar cell
s requires more energy than can be recovered in using
the solar cell . The result was refuted.
Another new concept that flows from life cycle assessments is Energy Cannibalism
. Energy Cannibalism refers to an effect where rapid
growth of an entire energy-intensive industry creates a need for
energy
that uses (or cannibalizes) the energy of existing power
plants. Thus during rapid growth the industry as a whole produces no
energy because new energy is used to fuel the embodied energy
of
future power plants. Work has been undertaken in the UK to determine the life cycle energy (alongside full LCA) impacts of a number of renewable technologies.
is recovered for electricity production.
A problem the energy analysis method cannot resolve is that different energy forms (heat
, electricity
, chemical energy
etc.) have different quality and value even in natural sciences, as a consequence of the two main laws of thermodynamics
. A thermodynamic measure of the quality of energy is exergy
. According to the first law of thermodynamics
, all energy inputs should be accounted with equal weight, whereas by the second law
diverse energy forms should be accounted by different values.
The conflict is resolved in one of these ways:
to systems thinking
. The accuracy and availability of data can also contribute to inaccuracy. For instance, data from generic processes may be based on averages, unrepresentative sampling, or outdated results. Additionally, social implications of products are generally lacking in LCAs. Comparative life-cycle analysis is often used to determine a better process or product to use. However, because of aspects like differing system boundaries, different statistical information, different product uses, etc., these studies can easily be swayed in favor of one product or process over another in one study and the opposite in another study based on varying parameters and different available data. There are guidelines to help reduce such conflicts in results but the method still provides a lot of room for the researcher to decide what is important, how the product is typically manufactured, and how it is typically used.
An in-depth review of 13 LCA studies of wood and paper products founda lack of consistency in the methods and assumptions used to track carbon during the product life cycle. A wide variety of methods and assumptions were used, leading to different and potentially contrary conclusions – particularly with regard to carbon sequestration and methane generation in landfills and with carbon accounting during forest growth and product use.
The Agroecology
tool "agroecosystem analysis
" offers a framework to incorporate incommensurable aspects of the life cycle of a product (such as social impacts, and soil and water implications). This tool is specifically useful in the analysis of a product made from agricultural materials such as corn ethanol
or soybean biodiesel
because it can account for an ecology of contexts
interacting and changing through time. This analysis tool should not be used instead of life-cycle analysis, but rather, in conjunction with life-cycle analysis to produce a well-rounded assessment.
has begun to reflect the interactions between the current electrical grid and future energy technology
. Some papers have focused on energy
life cycle, while others have focused on carbon dioxide
and other greenhouse gases. The essential critique given by these sources is that when considering energy technology
, the growing nature of the power grid must be taken into consideration. If this is not done, a given class of energy technology
may emit more carbon dioxide
over its lifetime than it mitigates.
- Compiling an inventory of relevant energy and material inputs and environmental releases;
- Evaluating the potential impacts associated with identified inputs and releases;
- Interpreting the results to help you make a more informed decision.
Goals and purpose of LCA
The goal of LCA is to compare the full range of environmental effects assignable to products and services in order to improve processes, support policy and provide a sound basis for informed decisions.The term life cycle refers to the notion that a fair, holistic assessment requires the assessment of raw-material production, manufacture, distribution
Sustainable distribution
Sustainable distribution refers to any means of transportation / hauling of goods between vendor and purchaser with lowest possible impact on the ecological and social environment, and includes the whole distribution process from storage, order processing and picking, packaging, improved vehicle...
, use and disposal including all intervening transportation steps necessary or caused by the product's existence.
There are two main types of LCA. Attributional LCAs seek to establish the burdens associated with the production and use of a product, or with a specific service or process, at a point in time (typically the recent past). Consequential LCAs seek to identify the environmental consequences of a decision or a proposed change in a system under study (oriented to the future), which means that market and economic implications of a decision may have to be taken into account. Social LCA is under development as a different approach to life cycle thinking intended to assess social implications or potential impacts. Social LCA should be considered as an approach that is complementary to environmental LCA.
The procedures of life cycle assessment (LCA) are part of the ISO 14000
ISO 14000
The ISO 14000 environmental management standards exist to help organizations minimize how their operations negatively affect the environment The ISO 14000 environmental management standards exist to help organizations (a) minimize how their operations (processes etc.) negatively affect the...
environmental management standards: in ISO 14040:2006 and 14044:2006. (ISO 14044 replaced earlier versions of ISO 14041 to ISO 14043.)
Four main phases
Goal and scope
An LCA starts with an explicit statement of the goal and scope of the study, which sets out the context of the study and explains how and to whom the results are to be communicated. This is a key step and the ISO standards require that the goal and scope of an LCA be clearly defined and consistent with the intended application. The goal and scope document therefore includes technical details that guide subsequent work:- the functional unit, which defines what precisely is being studied and quantifies the service delivered by the product system, providing a reference to which the inputs and outputs can be related;
- the system boundaries;
- any assumptions and limitations;
- the allocation methods used to partition the environmental load of a process when several products or functions share the same process; and
- the impact categories chosen.
Life cycle inventory
Life Cycle Inventory (LCI) analysis involves creating an inventory of flows from and to nature for a product system. Inventory flows include inputs of water, energy, and raw materials, and releases to air, land, and water. To develop the inventory, a flow model of the technical system is constructed using data on inputs and outputs. The flow model is typically illustrated with a flow chart that includes the activities that are going to be assessed in the relevant supply chain and gives a clear picture of the technical system boundaries. The input and output data needed for the construction of the model are collected for all activities within the system boundary, including from the supply chain (referred to as inputs from the technosphere).The data must be related to the functional unit defined in the goal and scope definition. Data can be presented in tables and some interpretations can be made already at this stage. The results of the inventory is an LCI which provides information about all inputs and outputs in the form of elementary flow to and from the environment from all the unit processes involved in the study.
Inventory flows can number in the hundreds depending on the system boundary. For product LCAs at either the generic (i.e., representative industry averages) or brand-specific level, that data is typically collected through survey questionnaires. At an industry level, care has to be taken to ensure that questionnaires are completed by a representative sample of producers, leaning toward neither the best nor the worst, and fully representing any regional differences due to energy use, material sourcing or other factors. The questionnaires cover the full range of inputs and outputs, typically aiming to account for 99% of the mass of a product, 99% of the energy used in its production and any environmentally sensitive flows, even if they fall within the 1% level of inputs.
One area where data access is likely to be difficult is flows from the technosphere. Those completing a questionnaire will be able to specify how much of a given input they use from supply chain sources, but they will not usually have access to data concerning inputs and outputs for those production processes. The entity undertaking the LCA must then turn to secondary sources if it does not already have that data from its own previous studies. National databases or data sets that come with LCA-practitioner tools, or that can be readily accessed, are the usual sources for that information. Care must then be taken to ensure that the secondary data source properly reflects regional or national conditions.
Life cycle impact assessment
Inventory analysis is followed by impact assessment. This phase of LCA is aimed at evaluating the significance of potential environmental impacts based on the LCI flow results. Classical Life Cycle Impact Assessment (LCIA) consists of the following mandatory elements:- selection of impact categories, category indicators, and characterization models;
- the classification stage, where the inventory parameters are sorted and assigned to specific impact categories; and
- impact measurement, where the categorized LCI flows are characterized, using one of many possible LCIA methodologies, into common equivalence units that are then summed to provide an overall impact category total.
In many LCAs, characterization concludes the LCIA analysis; this is also the last compulsory stage according to ISO 14044:2006. However, in addition to the above mandatory LCIA steps, other optional LCIA elements – normalization, grouping, and weighting – may be conducted depending on the goal and scope of the LCA study. In normalization, the results of the impact categories from the study are usually compared with the total impacts in the region of interest, the U.S. for example. Grouping consists of sorting and possibly ranking the impact categories. During weighting, the different environmental impacts are weighted relative to each other so that they can then be summed to get a single number for the total environmental impact. ISO 14044:2006 generally advises against weighting, stating that “weighting, shall not be used in LCA studies intended to be used in comparative assertions intended to be disclosed to the public”. This advice is often ignored, resulting in comparisons that can reflect a high degree of subjectivity as a result of weighting.
Interpretation
Life Cycle Interpretation is a systematic technique to identify, quantify, check, and evaluate information from the results of the life cycle inventory and/or the life cycle impact assessment. The results from the inventory analysis and impact assessment are summarized during the interpretation phase. The outcome of the interpretation phase is a set of conclusions and recommendations for the study. According to ISO 14040:2006, the interpretation should include:- identification of significant issues based on the results of the LCI and LCIA phases of an LCA;
- evaluation of the study considering completeness, sensitivity and consistency checks; and
- conclusions, limitations and recommendations.
A key purpose of performing life cycle interpretation is to determine the level of confidence in the final results and communicate them in a fair, complete, and accurate manner. Interpreting the results of an LCA is not as simple as 3 is better than 2, therefore Alternative A is the best choice! Interpreting the results of an LCA starts with understanding the accuracy of the results, and ensuring they meet the goal of the study. This is accomplished by identifying the data elements that contribute significantly to each impact category, evaluating the sensitivity of these significant data elements, assessing the completeness and consistency of the study, and drawing conclusions and recommendations based on a clear understanding of how the LCA was conducted and the results were developed.
Reference test
More specifically, the best alternative is the one that the LCA shows to have the least cradle-to-grave environmental negative impact on land, sea, and air resources.LCA tools and uses
There are two basic types of LCA tools:- dedicated software packages intended for practitioners; and
- tools with the LCA in the background intended for people who want LCA-based results without have to actually develop the LCA data and impact measures.
In the former category, the three principal tools are GaBi Software, developed by PE International, SimaPro, developed by PRé Consultants, and umberto, developed by ifu Hamburg GmbH. In the second category, different tools operate at different levels. At the product level, the U.S. National Institute of Standards and Technology (NIST) makes its BEES (Building for Environmental and Economic Sustainability) tool freely available and PTC’s Windchill Product Analytics makes LCA results an integral part of product development systems. At the whole building design level, different tools are available in different parts of the world. For example, the ATHENA® Impact Estimator for Buildings is capable of modeling 95% of the building stock in North America, Envest has been developed by the Building Research Establishment to meet UK needs, and EcoQuantum is available in the Netherlands. For the Netherlands, extensive databases (open access) are available on the so called eco-costs
Eco-costs
Eco-costs are a measure to express the amount of environmental burden of a product on the basis of prevention of that burden. They are the costs which should be made to reduce the environmental pollution and materials depletion in our world to a level which is in line with the carrying capacity of...
and carbon footprint of buildings and its components, see winket. The European Council of Construction Economists is planning to develop such open source databases for other European countries as well. At a building assembly level (e.g., exterior walls) the free ATHENA® EcoCalculator for Assemblies is an example of a tool that serves North America and the Whole Building Design Guide is an example of a tool applicable to the UK.
Based on a survey of LCA practitioners carried out in 2006 LCA is mostly used to support business strategy (18%) and R&D (18%), as input to product or process design (15%), in education (13%) and for labeling or product declarations (11%).
Major corporations all over the world are either undertaking LCA in house or commissioning studies, while governments support the development of national databases to support LCA. Of particular note is the growing use of LCA for ISO Type III labels called Environmental Product Declarations, defined as "quantified environmental data for a product with pre-set categories of parameters based on the ISO 14040 series of standards, but not excluding additional environmental information". These third-party certified LCA-based labels provide an increasingly important basis for assessing the relative environmental merits of competing products.
Data analysis
A life cycle analysis is only as valid as its dataData
The term data refers to qualitative or quantitative attributes of a variable or set of variables. Data are typically the results of measurements and can be the basis of graphs, images, or observations of a set of variables. Data are often viewed as the lowest level of abstraction from which...
; therefore, it is crucial that data used for the completion of a life cycle analysis is accurate and current. When comparing different life cycle analyses with one another, it is crucial that equivalent data is available for both products or processes in question. If one product has a much higher availability of data, it cannot be justly compared to another product which has less detailed data.
There are two basic types of LCA data – unit process data and environmental input-output data (EIO), where the latter is based on national economic input-output data. Unit process data is derived from direct surveys of companies or plants producing the product of interest, carried out at a unit process level defined by the system boundaries for the study.
Data validity is an ongoing concern for life cycle analyses. Due to globalization
Globalization
Globalization refers to the increasingly global relationships of culture, people and economic activity. Most often, it refers to economics: the global distribution of the production of goods and services, through reduction of barriers to international trade such as tariffs, export fees, and import...
and the rapid pace of research and development
Research and development
The phrase research and development , according to the Organization for Economic Co-operation and Development, refers to "creative work undertaken on a systematic basis in order to increase the stock of knowledge, including knowledge of man, culture and society, and the use of this stock of...
, new materials and manufacturing methods are continually being introduced to the market. This makes it both very important and very difficult to use up-to-date information when performing an LCA. If an LCA’s conclusions are to be valid, the data must be recent; however, the data-gathering process takes time. If a product and its related processes have not undergone significant revisions since the last LCA data was collected, data validity is not a problem. However, consumer electronics
Consumer electronics
Consumer electronics are electronic equipment intended for everyday use, most often in entertainment, communications and office productivity. Radio broadcasting in the early 20th century brought the first major consumer product, the broadcast receiver...
such as cell phones can be redesigned as often as every 9 to 12 months, creating a need for ongoing data collection.
The life cycle considered usually consists of a number of stages including: materials extraction, processing and manufacturing, product use, and product disposal. If the most environmentally harmful of these stages can be determined, then impact on the environment can be efficiently reduced by focusing on making changes for that particular phase. For example, the most energy-intensive life phase of an airplane or car is during use due to fuel consumption. One of the most effective ways to increase fuel efficiency is to decrease vehicle weight, and thus, car and airplane manufacturers can decrease environmental impact in a significant way by replacing aluminum with lighter materials such as carbon fiber reinforced fibers. The reduction during the use phase should be more than enough to balance additional raw material or manufacturing cost
Manufacturing cost
Manufacturing cost is the sum of costs of all resources consumed in the process of making a product. The manufacturing cost is classified into three categories: direct materials cost, direct labor cost and manufacturing overhead.- Direct materials cost :...
.
Cradle-to-grave
Cradle-to-grave is the full Life Cycle Assessment from resource extraction ('cradle') to use phase and disposal phase ('grave'). For example, trees produce paper, which can be recycled into low-energy production celluloseCellulose
Cellulose is an organic compound with the formula , a polysaccharide consisting of a linear chain of several hundred to over ten thousand β linked D-glucose units....
(fiberised paper) insulation
Building insulation
building 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...
, then used as an energy-saving device in the ceiling of a home for 40 years, saving 2,000 times the fossil-fuel
Fossil fuel
Fossil fuels are fuels formed by natural processes such as anaerobic decomposition of buried dead organisms. The age of the organisms and their resulting fossil fuels is typically millions of years, and sometimes exceeds 650 million years...
energy used in its production. After 40 years the cellulose
Cellulose
Cellulose is an organic compound with the formula , a polysaccharide consisting of a linear chain of several hundred to over ten thousand β linked D-glucose units....
fibers are replaced and the old fibers are disposed of, possibly incinerated. All inputs and outputs are considered for all the phases of the life cycle.
Cradle-to-gate
Cradle-to-gate is an assessment of a partial product life cycle from resource extraction('cradle') to the factory gate (i.e., before it is transported to the consumer). The use phase and disposal phase of the product are omitted in this case. Cradle-to-gate assessments are sometimes the basis for environmental product declarations (EPD) termed business-to-business EDPs.Cradle-to-Cradle or Open Loop Production
Cradle-to-cradle is a specific kind of cradle-to-grave assessment, where the end-of-life disposal step for the product is a recyclingRecycling
Recycling is processing used materials into new products to prevent waste of potentially useful materials, reduce the consumption of fresh raw materials, reduce energy usage, reduce air pollution and water pollution by reducing the need for "conventional" waste disposal, and lower greenhouse...
process. It is a method used to minimize the environmental impact of products by employing sustainable production, operation, and disposal practices and aims to incorporate social responsibility into product development. From the recycling process originate new, identical products (e.g., asphalt pavement from discarded asphalt pavement, glass bottles from collected glass bottles), or different products (e.g., glass wool insulation from collected glass bottles).
Allocation of burden for products in open loop production systems presents considerable challenges for LCA. Various methods, such as the avoided burden
Avoided burden
Avoided burden is an approach used in Life Cycle Assessment , especially in the context of allocating environmental burden in the presence of recycling or reuse. When determining the overall environmental impact of a product, the product is given "credit" for the potential recycled material included...
approach have been proposed to deal with the issues involved.
Gate-to-gate
Gate-to-gate is a partial LCA looking at only one value-added process in the entire production chain. Gate-to-gate modules may also later be linked in their appropriate production chain to form a complete cradle-to-gate evaluation.Well-to-wheel
Well-to-wheel is the specific LCA used for transportTransport
Transport or transportation is the movement of people, cattle, animals and goods from one location to another. Modes of transport include air, rail, road, water, cable, pipeline, and space. The field can be divided into infrastructure, vehicles, and operations...
fuel
Fuel
Fuel is any material that stores energy that can later be extracted to perform mechanical work in a controlled manner. Most fuels used by humans undergo combustion, a redox reaction in which a combustible substance releases energy after it ignites and reacts with the oxygen in the air...
s and vehicles. The analysis is often broken down into stages entitled "well-to-station", or "well-to-tank", and "station-to-wheel" or "tank-to-wheel", or "plug-to-wheel". The first stage, which incorporates the feedstock or fuel production and processing and fuel delivery or energy transmission, and is called the "upstream" stage, while the stage that deals with vehicle operation itself is sometimes called the "downstream" stage. The well-to-wheel analysis is commonly used to assess total energy consumption, or energy conversion efficiency
Energy conversion efficiency
Energy conversion efficiency is the ratio between the useful output of an energy conversion machine and the input, in energy terms. The useful output may be electric power, mechanical work, or heat.-Overview:...
and emission
Emission
Emission may refer to:* Flue gas, also:** Exhaust gas, flue gas occurring as a result of the combustion of a fuel* Emission of air pollutants...
s impact of marine vessels, aircraft
Aircraft
An aircraft is a vehicle that is able to fly by gaining support from the air, or, in general, the atmosphere of a planet. An aircraft counters the force of gravity by using either static lift or by using the dynamic lift of an airfoil, or in a few cases the downward thrust from jet engines.Although...
s and motor vehicle emissions
Motor vehicle emissions
Motor vehicle emissions are composed of the by-products that comes out of the exhaust systems or other emissions such as gasoline evaporation...
, including their carbon footprint
Carbon footprint
A carbon footprint has historically been defined as "the total set of greenhouse gas emissions caused by an organization, event, product or person.". However, calculating a carbon footprint which conforms to this definition is often impracticable due to the large amount of data required, which is...
, and the fuels used in each of these transport modes.
The well-to-wheel variant has a significant input on a model developed by the Argonne National Laboratory
Argonne National Laboratory
Argonne National Laboratory is the first science and engineering research national laboratory in the United States, receiving this designation on July 1, 1946. It is the largest national laboratory by size and scope in the Midwest...
. The Greenhouse gases, Regulated Emissions, and Energy use in Transportation (GREET) model was developed to evaluate the impacts of new fuels and vehicle technologies. The model evaluates the impacts of fuel use using a well-to-wheel evaluation while a traditional cradle-to-grave approach is used to determine the impacts from the vehicle itself. The model reports energy use, greenhouse gas emissions, and six additional pollutants: volatile organic compounds (VOCs), carbon monoxide
Carbon monoxide
Carbon monoxide , also called carbonous oxide, is a colorless, odorless, and tasteless gas that is slightly lighter than air. It is highly toxic to humans and animals in higher quantities, although it is also produced in normal animal metabolism in low quantities, and is thought to have some normal...
(CO), nitrogen oxide
Nitrogen oxide
Nitrogen oxide can refer to a binary compound of oxygen and nitrogen, or a mixture of such compounds:* Nitric oxide, also known as nitrogen monoxide, , nitrogen oxide* Nitrogen dioxide , nitrogen oxide...
(NOx), particulate matter with size smaller than 10 micrometre (PM10), particulate matter with size smaller than 2.5 micrometre (PM2.5), and sulfur oxides (SOx).
Economic input–output life cycle assessment
Economic input–output LCA (EIOLCAEIOLCA
Economic input-output life cycle assessment, or EIO-LCA involves use of aggregate sector-level data quantifying how much environmental impact can be directly attributed to each sector of the economy and how much each sector purchases from other sectors in producing its output...
) involves use of aggregate sector-level data on how much environmental impact can be attributed to each sector of the economy and how much each sector purchases from other sectors. Such analysis can account for long chains (for example, building an automobile requires energy, but producing energy requires vehicles, and building those vehicles requires energy, etc.), which somewhat alleviates the scoping problem of process LCA; however, EIOLCA relies on sector-level averages that may or may not be representative of the specific subset of the sector relevant to a particular product and therefore is not suitable for evaluating the environmental impacts of products. Additionally the translation of economic quantities into environmental impacts is not validated.
Ecologically-based LCA
While a conventional LCA uses many of the same approaches and strategies as an Eco-LCA, the latter considers a much broader range of ecological impacts. It was designed to provide a guide to wise management of human activities by understanding the direct and indirect impacts on ecological resources and surrounding ecosystems.Developed by Ohio State University Center for resilience, Eco-LCA is a methodology that quantitatively takes into account regulating and supporting services during the life cycle of economic goods and products. In this approach services are categorized in four main groups: supporting, regulating provisioning and cultural services.
Life cycle energy analysis
Life cycle energy analysis (LCEA) is an approach in which all energyEnergy
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...
inputs to a product are accounted for, not only direct energy inputs during manufacture, but also all energy inputs needed to produce components, materials and services needed for the manufacturing process. An earlier term for the approach was energy analysis.
With LCEA, the total life cycle energy input is established.
Energy production
It is recognized that much energy is lost in the production of energycommodities themselves, such as nuclear energy
Nuclear power
Nuclear power is the use of sustained nuclear fission to generate heat and electricity. Nuclear power plants provide about 6% of the world's energy and 13–14% of the world's electricity, with the U.S., France, and Japan together accounting for about 50% of nuclear generated electricity...
, photovoltaic
electricity
Electricity
Electricity is a general term encompassing a variety of phenomena resulting from the presence and flow of electric charge. These include many easily recognizable phenomena, such as lightning, static electricity, and the flow of electrical current in an electrical wire...
or high-quality petroleum products. Net energy
content is the energy content of the product minus energy input used
during extraction and conversion
Energy conversion
Transforming energy is when the energy changes into another form.In physics, the term energy describes the capacity to produce changes within a system, without regard to limitations in transformation imposed by entropy...
, directly or
indirectly.
A controversial early result of LCEA claimed that manufacturing
solar cell
Solar cell
A solar cell is a solid state electrical device that converts the energy of light directly into electricity by the photovoltaic effect....
s requires more energy than can be recovered in using
the solar cell . The result was refuted.
Another new concept that flows from life cycle assessments is Energy Cannibalism
Energy Cannibalism
Energy cannibalism refers to an effect where rapid growth of an entire energy producing industry creates a need for energy that uses the energy of existing power plants. Thus during rapid growth the industry as a whole produces no energy because new energy is used to fuel the embodied energy of...
. Energy Cannibalism refers to an effect where rapid
growth of an entire energy-intensive industry creates a need for
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...
that uses (or cannibalizes) the energy of existing power
plants. Thus during rapid growth the industry as a whole produces no
energy because new energy is used to fuel the embodied energy
Embodied energy
Embodied energy is defined as the sum of energy inputs that was used in the work to make any product, from the point of extraction and refining materials, bringing it to market, and disposal / re-purposing of it...
of
future power plants. Work has been undertaken in the UK to determine the life cycle energy (alongside full LCA) impacts of a number of renewable technologies.
Energy recovery
If materials are incinerated during the disposal process, the energy released during burning can be harnessed and used for electricity production. This provides a low-impact energy source, especially when compared with coal and natural gas While incineration produces more greenhouse gas emissions than landfilling, the waste plants are well-fitted with filters to minimize this negative impact. A recent study comparing energy consumption and greenhouse gas emissions from landfilling (without energy recovery) against incineration (with energy recovery) found incineration to be superior in all cases except for when landfill gasLandfill gas
Landfill gas is a complex mix of different gases created by the action of microorganisms within a landfill.-Production:Landfill gas production results from chemical reactions and microbes acting upon the waste as the putrescible materials begins to break down in the landfill...
is recovered for electricity production.
Criticism
A criticism of LCEA is that it attempts to eliminate monetary cost analysis, that is replace the currency by which economic decisions are made with an energy currency. It has also been argued that energy efficiency is only one consideration in deciding which alternative process to employ, and that it should not be elevated to the only criterion for determining environmental acceptability; for example, simple energy analysis does not take into account the renewability of energy flows or the toxicity of waste products; however the life cycle assessment does help companies become more familiar with environmental properties and improve their environmental system. Incorporating Dynamic LCAs of renewable energy technologies (using sensitivity analyses to project future improvements in renewable systems and their share of the power grid) may help mitigate this criticism.A problem the energy analysis method cannot resolve is that different energy forms (heat
Heat
In physics and thermodynamics, heat is energy transferred from one body, region, or thermodynamic system to another due to thermal contact or thermal radiation when the systems are at different temperatures. It is often described as one of the fundamental processes of energy transfer between...
, electricity
Electricity
Electricity is a general term encompassing a variety of phenomena resulting from the presence and flow of electric charge. These include many easily recognizable phenomena, such as lightning, static electricity, and the flow of electrical current in an electrical wire...
, chemical energy
Chemical energy
Chemical energy is the potential of a chemical substance to undergo a transformation through a chemical reaction or, to transform other chemical substances...
etc.) have different quality and value even in natural sciences, as a consequence of the two main laws of 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...
. A thermodynamic measure of the quality of energy is exergy
Exergy
In thermodynamics, the exergy of a system is the maximum useful work possible during a process that brings the system into equilibrium with a heat reservoir. When the surroundings are the reservoir, exergy is the potential of a system to cause a change as it achieves equilibrium with its...
. According to the first law of thermodynamics
First law of thermodynamics
The first law of thermodynamics is an expression of the principle of conservation of work.The law states that energy can be transformed, i.e. changed from one form to another, but cannot be created nor destroyed...
, all energy inputs should be accounted with equal weight, whereas by the second law
Second law of thermodynamics
The second law of thermodynamics is an expression of the tendency that over time, differences in temperature, pressure, and chemical potential equilibrate in an isolated physical system. From the state of thermodynamic equilibrium, the law deduced the principle of the increase of entropy and...
diverse energy forms should be accounted by different values.
The conflict is resolved in one of these ways:
- value difference between energy inputs is ignored,
- a value ratio is arbitrarily assigned (e.g., a jouleJouleThe joule ; symbol J) is a derived unit of energy or work in the International System of Units. It is equal to the energy expended in applying a force of one newton through a distance of one metre , or in passing an electric current of one ampere through a resistance of one ohm for one second...
of electricityElectricityElectricity is a general term encompassing a variety of phenomena resulting from the presence and flow of electric charge. These include many easily recognizable phenomena, such as lightning, static electricity, and the flow of electrical current in an electrical wire...
is 2.6 times more valuable than a joule of heat or fuel input), - the analysis is supplemented by economic (monetary) cost analysis,
- exergy instead of energy can be the metric used for the life cycle analysis.
Critiques
Life cycle assessment is a powerful tool for analyzing commensurable aspects of quantifiable systems. Not every factor, however, can be reduced to a number and inserted into a model. Rigid system boundaries make accounting for changes in the system difficult. This is sometimes referred to as the boundary critiqueBoundary critique
Boundary critique is the concept in critical systems thinking, according to Ulrich that states that "both the meaning and the validity of professional propositions always depend on boundary judgments as to what 'facts' and 'norms' are to be considered relevant" or not.Boundary critique is a...
to systems thinking
Systems thinking
Systems thinking is the process of understanding how things influence one another within a whole. In nature, systems thinking examples include ecosystems in which various elements such as air, water, movement, plants, and animals work together to survive or perish...
. The accuracy and availability of data can also contribute to inaccuracy. For instance, data from generic processes may be based on averages, unrepresentative sampling, or outdated results. Additionally, social implications of products are generally lacking in LCAs. Comparative life-cycle analysis is often used to determine a better process or product to use. However, because of aspects like differing system boundaries, different statistical information, different product uses, etc., these studies can easily be swayed in favor of one product or process over another in one study and the opposite in another study based on varying parameters and different available data. There are guidelines to help reduce such conflicts in results but the method still provides a lot of room for the researcher to decide what is important, how the product is typically manufactured, and how it is typically used.
An in-depth review of 13 LCA studies of wood and paper products founda lack of consistency in the methods and assumptions used to track carbon during the product life cycle. A wide variety of methods and assumptions were used, leading to different and potentially contrary conclusions – particularly with regard to carbon sequestration and methane generation in landfills and with carbon accounting during forest growth and product use.
The Agroecology
Agroecology
Agroecology is the application of ecological principles to the production of food, fuel, fiber, and pharmaceuticals. The term encompasses a broad range of approaches, and is considered "a science, a movement, [and] a practice."...
tool "agroecosystem analysis
Agroecosystem analysis
Agroecosystem analysis is a thorough analysis of an agricultural environment which considers aspects from ecology, sociology, economics, and politics with equal weight. There are many aspects to consider; however, it is literally impossible to account for all of them. This is one of the issues when...
" offers a framework to incorporate incommensurable aspects of the life cycle of a product (such as social impacts, and soil and water implications). This tool is specifically useful in the analysis of a product made from agricultural materials such as corn ethanol
Corn ethanol
Corn ethanol is ethanol produced from corn as a biomass through industrial fermentation, chemical processing and distillation. Corn is the main feedstock used for producing ethanol fuel in the United States and it is mainly used as an oxygenate to gasoline in the form of low-level blends, and to a...
or soybean biodiesel
Biodiesel
Biodiesel refers to a vegetable oil- or animal fat-based diesel fuel consisting of long-chain alkyl esters. Biodiesel is typically made by chemically reacting lipids with an alcohol....
because it can account for an ecology of contexts
Ecology of contexts
The ecology of contexts is a term used in many disciplines and refers to the dynamic interplay of contexts and demands that constrain and define an entity.-Environmental ecology:...
interacting and changing through time. This analysis tool should not be used instead of life-cycle analysis, but rather, in conjunction with life-cycle analysis to produce a well-rounded assessment.
Dynamic life cycle assessment
In recent years, the literature on life cycle assessment of energy technologyEnergy technology
Energy technology is an interdisciplinary engineering science having to do with the efficient, safe, environmentally friendly and economical extraction, conversion, transportation, storage and use of energy, targeted towards yielding high efficiency whilst skirting side effects on humans, nature...
has begun to reflect the interactions between the current electrical grid and future energy technology
Energy technology
Energy technology is an interdisciplinary engineering science having to do with the efficient, safe, environmentally friendly and economical extraction, conversion, transportation, storage and use of energy, targeted towards yielding high efficiency whilst skirting side effects on humans, nature...
. Some papers have focused 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...
life cycle, while others have focused on carbon dioxide
Carbon dioxide
Carbon dioxide is a naturally occurring chemical compound composed of two oxygen atoms covalently bonded to a single carbon atom...
and other greenhouse gases. The essential critique given by these sources is that when considering energy technology
Energy technology
Energy technology is an interdisciplinary engineering science having to do with the efficient, safe, environmentally friendly and economical extraction, conversion, transportation, storage and use of energy, targeted towards yielding high efficiency whilst skirting side effects on humans, nature...
, the growing nature of the power grid must be taken into consideration. If this is not done, a given class of energy technology
Energy technology
Energy technology is an interdisciplinary engineering science having to do with the efficient, safe, environmentally friendly and economical extraction, conversion, transportation, storage and use of energy, targeted towards yielding high efficiency whilst skirting side effects on humans, nature...
may emit more carbon dioxide
Carbon dioxide
Carbon dioxide is a naturally occurring chemical compound composed of two oxygen atoms covalently bonded to a single carbon atom...
over its lifetime than it mitigates.
See also
- AgroecologyAgroecologyAgroecology is the application of ecological principles to the production of food, fuel, fiber, and pharmaceuticals. The term encompasses a broad range of approaches, and is considered "a science, a movement, [and] a practice."...
- Agroecosystem analysisAgroecosystem analysisAgroecosystem analysis is a thorough analysis of an agricultural environment which considers aspects from ecology, sociology, economics, and politics with equal weight. There are many aspects to consider; however, it is literally impossible to account for all of them. This is one of the issues when...
- Anthropogenic metabolismAnthropogenic metabolism"Anthropogenic metabolism" is a term used in material flow analysis, substance flow analysis and waste management. It includes: "not only the physiological metabolism but also includes the thousands of goods and substances necessary to sustain modern life. Anthropogenic stands for man-made...
- BiofuelBiofuelBiofuel is a type of fuel whose energy is derived from biological carbon fixation. Biofuels include fuels derived from biomass conversion, as well as solid biomass, liquid fuels and various biogases...
- Carbon footprintCarbon footprintA carbon footprint has historically been defined as "the total set of greenhouse gas emissions caused by an organization, event, product or person.". However, calculating a carbon footprint which conforms to this definition is often impracticable due to the large amount of data required, which is...
- Cradle to CradleCradle to CradleCradle-to-cradle design is a biomimetic approach to the design of systems. It models human industry on nature's processes in which materials are viewed as nutrients circulating in healthy, safe metabolisms...
- Design for EnvironmentDesign for EnvironmentDesign for the Environment Program is a United States Environmental Protection Agency program, created in 1992, that works to prevent pollution, and the risk pollution presents to humans and the environment. The EPA DfE program provides information regarding safer electronics, safer flame...
- Dimension stoneDimension stoneDimension stone is natural stone or rock that has been selected and fabricated to specific sizes or shapes. Color, texture and pattern, and surface finish of the stone are also normal requirements...
Stone: life-cycle assessment and best practices
- End-of-life (product)
- Environmental pricing reformEnvironmental pricing reformEnvironmental pricing reform is the process of adjusting market prices to include environmental costs and benefits.An externality exists where a market price omits environmental costs and/or benefits...
- Greenhouse gasGreenhouse gasA greenhouse gas is a gas in an atmosphere that absorbs and emits radiation within the thermal infrared range. This process is the fundamental cause of the greenhouse effect. The primary greenhouse gases in the Earth's atmosphere are water vapor, carbon dioxide, methane, nitrous oxide, and ozone...
- GREET ModelGREET ModelGREET is a full life-cycle model sponsored by the Argonne National Laboratory...
- Industrial ecologyIndustrial ecologyIndustrial Ecology is the study of material and energy flows through industrial systems. The global industrial economy can be modeled as a network of industrial processes that extract resources from the Earth and transform those resources into commodities which can be bought and sold to meet the...
- ISO 15686ISO 15686ISO 15686 is the in development ISO standard dealing with service life planning. It is a decision process which addresses the development of the service life of a building component, building or other constructed work like a bridge or tunnel...
- Industrial metabolismIndustrial metabolismIndustrial metabolism was first proposed by Robert Ayres as "the whole integrated collection of physical processes that convert raw materials and energy, plus labour, into finished products and wastes..." The goal is to study the flow of materials through society in order to better understand the...
- Whole-life costWhole-life costWhole-life cost, or Life-cycle cost , refers to the total cost of ownership over the life of an asset . Also commonly referred to as "cradle to grave" or "womb to tomb" costs. Costs considered include the financial cost which is relatively simple to calculate and also the environmental and...
Further reading
- Thomas,J.A.G., ed: Energy Analysis, ipc science and technology press & Westview Press, 1977, ISBN 0-902852-60-4 or ISBN 0-89158-813-2
- Crawford, R.H. (2011) Life Cycle Assessment in the Built Environment, London: Taylor and Francis.
- M.W.Gilliland ed: Energy Analysis: A New Public Policy Tool, AAA Selected Symposia Series, Westview Press, Boulder, Colorado, 1978., ISBN 0-89158-437-4
- Center for Life Cycle Analysis, Columbia University, New York
- J. Guinée, ed:, Handbook on Life Cycle Assessment: Operational Guide to the ISO Standards, Kluwer Academic Publishers, 2002.
- Hendrickson, C. T., Lave, L. B., and Matthews, H. S. (2005). Environmental Life Cycle Assessment of Goods and Services: An Input–Output Approach, Resources for the Future Press.
- Baumann, H. och Tillman, A-M. The hitchhiker's guide to LCA : an orientation in life cycle assessment methodology and application. 2004. ISBN 91-44-02364-2
- Crawford, R.H. (2008) Validation of a Hybrid Life-Cycle Inventory Analysis Method, Journal of Environmental Management, 88(3), 496–506.
- Jimenez-Gonzalez, C., et al. 2004. Cradle to Gate Life Cycle Inventory and Assessment of Pharmeceutical Compounds. Intr J LCA. 9(2): 114-121.
- Curran, Mary A. "Environmental Life-Cycle Assessment", McGraw-Hill Professional Publishing, 1996, ISBN 978-0070150638
- Kim, S. and Dale, B.E. Life cycle assessment of various cropping systems utilized for producing biofuels: Bioethanol and biodiesel. Biomass & Bioenergy 2005, 29, 426-439.
- Ciambrone, D. F. (1997). Environmental Life Cycle Analysis. Boca Raton, FL: CRC Press. ISBN 1-56670-214-3.
- Horne,Ralph., et al. "LCA: Principles, Practice and Prospects". CSIRO Publishing,Victoria, Australia, 2009., ISBN 0-64309-452-0
- Trusty, Wayne, “An Overview of Life Cycle Assessments: Part One”, International Code Council Building Safety Journal Online, October 2010, http://bsj.iccsafe.org/2010Oct/features/lca.html.
- Vigon, B. W. (1994). Life-Cycle Assessment: Inventory Guidelines and Principles. Boca Raton, FL: CRC Press. ISBN 1-56670-015-9.
- Vogtländer,J.G., “A practical guide to LCA for students, designers, and business managers”, VSSD, 2010, ISBN 978-90-6562-253-2.
External links
- The European Commission's Directory of LCA services, tools, databases, and provider
- The European Commission's LCA database ELCD (free of charge)
- UNEP/SETAC Life Cycle Initiative; a stakeholder financed project
- Life-cycle.org – links to LCA sites and resources.
- Department Life Cycle Engineering – LBP – University of Stuttgart.
- Embodied Energy: Life Cycle Assessment. Your Home Technical Manual. A joint initiative of the Australian Government and the design and construction industries.(archived from 2007)
- LCA research at the Center for Environmental Sciences, Leiden University
- Explanation of LCA from the American Chemistry Council
- The National Risk Management Research Laboratory's LCA website