Partitioning the input or output flows of a process or a product system between the product system under study and one or more other product systems.

Average Data

Data representative of a product, product group or construction service, provided by more than one supplier.

Carbon Footprint

The carbon footprint of a product is the quantity of greenhouse gases emitted during specified life cycle stages – e.g. cradle to gate, cradle to site, or cradle to grave. The carbon footprint is typically expressed in mass of carbon dioxide equivalent (e.g. kg CO2 eq (100 years)) though earlier studies sometimes excluded other greenhouse gases and only focussed on carbon dioxide.

CEN TC 350

CEN TC 350 is the Technical Committee with the European Standards organisation, CEN, which is working on the European Commission’s Mandate 350, to develop horizontal standardised methods for the assessment of the integrated environmental performance of buildings. TC 350 has published many of the standards within this mandate.

Closed Loop & Open Loop

A closed-loop allocation procedure applies to closed-loop product systems. It also applies to open-loop product systems where no changes occur in the inherent properties of the recycled material. In such cases, the need for allocation is avoided since the use of secondary material displaces the use of virgin (primary) materials.

An open-loop allocation procedure applies to open-loop product systems where the material is recycled into other product systems and the material undergoes a change to its inherent properties.


Any marketable materials, products or fuels generated from the same unit process as the object of the assessment.

Note 1: Co-product, by-product and product have the same status and are used for identification of several distinguished flows of products from the same unit process. From co-product, by-product and product, waste is the only output to be distinguished as a non-product.

Cradle through Construction

In addition to the modules covered in cradle to site, this life cycle stage also covers the following:

  • transport of materials to the building site, which are then wasted through the construction process;
  • installation into the building;

This is covered by TC350 modules A1-A5 and may be declared as aggregated modules A1-3 (product stage) and individual A4 and A5.

Cradle to Cradle

A holistic economic, industrial and social framework that seeks to create systems that are not only efficient but also essentially waste free, providing “food” to other systems.  Cradle to Cradle®  was developed by Michael Braungart and William McDonough.  Multilevel certification is possible against performance in 5 categories. 

Cradle to Gate

Addresses the environmental aspects and potential environmental impacts (e.g. use of resources and environmental consequences of releases) throughout a product's life cycle from raw material acquisition until the end of the production process (“gate of the factory”).

This is covered by TC350 modules A1, A2 and A3 and may be declared as one aggregated module A1-3 as defined by CEN TC350.

Cradle to Grave

Addresses the environmental aspects and potential environmental impacts (e.g. use of resources and environmental consequences of releases) throughout a product's life cycle from raw material acquisition until the end of life.

This is covered by TC350 modules A1-A5, B1-B7 and C1-C4 as defined by CEN TC350.

Cradle to Site

In addition to the modules covered in cradle to gate, this life cycle stage also covers the transport of the product to the construction site.

This is covered by TC350 modules A1, A2, A3 and A4.

Declared Unit

This is the quantity of product on which the LCA is based. This is typically reported in units of mass (kg) or volume (m3), but surface area (m2) is used sometimes. 

Delivered Energy 

The total energy, expressed per energy carrier, supplied to the technical building system through the system boundary to satisfy the uses taken into account (heating, cooling, ventilation, domestic hot water, lighting, appliances etc.) or to produce electricity

Note 1: For active solar and wind energy systems the incident solar radiation on solar panels or on solar collectors or the kinetic energy of wind is not part of the energy balance of the building. Renewable energy produced on site is part of the delivered energy.

Note 2: Delivered energy can be calculated for defined energy uses or it can be measured.

Downstream Processes 

Processes that occur after the designated process in the product life cycle.

Embodied Carbon

Embodied carbon is the greenhouse gas emissions associated with all life cycle stages of a product or building, except carbon emissions from use of operational energy and water within the use phase. It should include the carbon emissions associated with the extraction, transport, manufacture, assembly, installation, maintenance, disassembly or demolition and disposal of the product.

Embodied carbon may be reported based on a more limited scope (e.g. only considering cradle to gate processes) so it is important that the life cycle stages for which embodied carbon is reported are clearly stated. It is also important to clarify whether just carbon dioxide (kg CO2 or kg C) or all greenhouse gases (kg CO2 eq) have been taken into account.

Embodied Energy

The embodied energy of a product relates to the primary energy demand with all life cycle stages of a product except from use of operational energy and water within the use phase. Embodied energy would also include feedstock energy (eg use of crude oil within plastics). Embodied energy was the first materials-related indicator to be measured by the construction industry but has now been overtaken by embodied carbon and life cycle assessment. 

Embodied Impacts

Embodied impact relates to those impacts associated with the production of materials and products and their transport, maintenance, repair, replacement and treatment and disposal at the end of life.

Environmental Impact 

Change to the environment, whether adverse or beneficial, resulting from human activities or natural events.

Environmental Product Declaration

An EPD (Environmental Product Declaration) is a document that provides environmental impact data about a product. EPD should be produced in accordance with ISO 14025 using product category rules (PCR) and verified by an independent party. This often means third-party verification but this is only essential in the case of business-to-consumer declarations. 

Construction Product EPD should now follow EN 15804, the recent TC350 standard for EPD in Europe, or ISO 21930 outside of Europe.

EPD Programme Operator

A body or bodies that manage a Type III environmental declaration programme. 

Feedstock Energy

Feedstock energy is the energy content of materials within a product, which can be either non-renewable (fossil) or renewable (biogenic). This covers, for example, the energy content of timber or wood fibre incorporated within products, or oil within plastics.

Functional Unit

Quantified performance of a product system for use as a reference unit.

Generic Data

Data that are not based on direct measurements or calculation for the respective specific process(es). Generic data can be either sector-specific, (i.e. specific to the sector being considered) or multi-sector. Examples of generic data include:

  • Data from literature or scientific papers;
  • Industry-average life cycle data from life cycle inventory databases, industry association reports, government statistics, etc.  

Greenhouse Gas

A gas that absorbs radiation at specific wavelengths within the spectrum of infrared radiation emitted by the Earth’s surface and by clouds. The gas in turn re-emits infrared radiation in all directions, including back to the Earth’s surface. The net effect is a local trapping of part of the absorbed energy and a tendency to warm the planetary surface. Water vapour (H2O), carbon dioxide (CO2), nitrous oxide (N2O), methane (CH4) and ozone (O3) are the primary greenhouse gases in the Earth’s atmosphere. 

GWP (Global Warming Potential)

Greenhouse gases (GHG), such as methane and nitrous oxide, act in the same way as CO2 by trapping heat in the atmosphere. In scientific terms this is known as radiative forcing. GWP is a relative measure of the amount of CO2 which would need to be released to have the same radiative forcing effect as a release of 1 kg of the GHG over a particular time period. Global warming potential is therefore expressed in mass of carbon dioxide equivalent. 

Life Cycle

A unit operations view of consecutive and interlinked stages of a product system, from raw material acquisition or generation from natural resources to final disposal. This includes all materials and energy input as well as waste generated to air, land and water.

Life Cycle Assessment – LCA

Compilation and evaluation of the inputs, outputs and the potential environmental impacts of a product system throughout its life cycle.

Life Cycle Impact Assessment – LCIA

Phase of life cycle assessment aimed at understanding and evaluating the magnitude and significance of the potential environmental impacts for a product system throughout the life cycle of the product.

Life Cycle Interpretation

Phase of life cycle assessment in which the findings of either the inventory analysis or the impact assessment, or both, are evaluated in relation to the defined goal and scope in order to reach conclusions and recommendations.

Life Cycle Inventory – LCI

Phase of life cycle assessment involving the compilation and quantification of inputs and outputs for a product throughout its life cycle.

Non-renewable Energy

Energy sourced from fuel resources which exist in finite quantities that cannot be replenished on a human timescale. 

Non-renewable Resource 

Material resource which exists in finite quantities that cannot be replenished on a human timescale.


The process by which a negative environmental impact can be counteracted by a corresponding opposing positive environmental impact. 

Primary Energy

Energy embodied in natural resources (e.g. coal, crude oil, sunlight, uranium) that has not undergone any anthropogenic conversion or transformation. 

Product Category Rules (PCR)

A set of specific rules, requirements and guidelines for developing Type III environmental declarations (3.2) for one or more product categories.

Renewable Energy

Energy sourced from resources that are grown, naturally replenished or cleansed on a human time scale.

Examples: Energy from biomass, wind power, solar power, hydropower etc.

Renewable Resources

A material resource that is grown, naturally replenished or cleansed on a human time scale.

Examples: Trees in forests, grasses in grasslands and fertile soil.

Note: A renewable resource is capable of being exhausted but can last indefinitely with proper stewardship.


The process of increasing the carbon content of a carbon reservoir other than the atmosphere. Biological approaches to sequestration include direct removal of carbon dioxide from the atmosphere through afforestation, reforestation and practices that enhance soil carbon in agriculture.

Physical approaches include separation and disposal of carbon dioxide from flue gases or from processing fossil fuels to produce hydrogen and carbon dioxide rich fractions and long-term storage underground in depleted oil and gas reservoirs, coal seams, and saline aquifers. See also uptake.

Specific Data

Data which are specific to the product which is the subject of assessment.

System Boundary

Set of criteria specifying which unit processes are part of a product system. Any product system will make use of raw materials, energy or land and produce materials which are discarded into the environment without further intervention (e.g. landfill or incineration emissions). These cross a boundary between the environment and the economy and only those which are related to the economy are included within the system boundary. The system boundary with nature must therefore be defined. Additionally, cut-off rules ignoring irrelevant processes and allocation rules between the product system and other related products systems (e.g. recycling systems) must be defined to establish the system boundary.

Type I Declaration – Ecolabel

Declaration from a voluntary, multiple-criteria-based third party environmental labelling programme that awards a licence which authorises the use of environmental labels on products indicating overall environmental preferability of a product within a particular product category based on life cycle considerations.

Type II Declaration – Self declared environmental claim

Environmental claim that is made without independent third-party certification by manufacturers, importers, distributors, retailers or anyone else likely to benefit from such a claim.

Type III Declaration – Environmental Product Declaration (EPD)

Independently verified environmental declaration providing quantified environmental data using predetermined parameters and, where relevant, additional environmental information.

Upstream Processes 

Processes occurring before the designated process in the product life cycle.




Abiotic Depletion Potential


Acidification Potential


Building Information Modelling


Cross Laminated Timber


Centre of Environmental Science at Leiden University


European Life Cycle Database




Eutrophication Potential


Environmental Product Declaration


Ganzheitliche Bilanzierung (German for holistic balancing)


Greenhouse Gas


Global Warming Potential


High Density Fibreboard


International Cycle Data System


Intergovernmental Panel on Climate Change


International Organization for Standardization


Life Cycle Assessment


Life Cycle Inventory


Life Cycle Impact Assessment


Laminated Strand Lumber


Laminated Veneer Lumber


Medium Density Fibreboard


Ozone Depletion Potential


Organisation Environmental


Oriented Strand Board


PE International


Product Environmental Footprint


Photochemical Ozone Creation Potential


Parallel Strand Lumber

User Guide

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