Impact Assessment Categories (CML, TRACI, and PEF)

Which Impact Assessment Categories are supported?

The impact categories offered for each of the calculation tools depend on the purpose of the tool. For instance, carbon tools often report only on Global Warming potential, while LCA tools according to CML might report only on the 6 main CML indicators. TRACI is only supported in North American tools or global carbon tools. Only a small number of tools as of today utilize solely PEF data.

ReCiPe is not described as this is not commonly used in building or product LCA assessments.

• CML (Used worldwide - except North America)

One Click LCA supports all the 24 impact categories listed in EN 15804 based on CML methodology.

For all the tools targeting European markets, the impact assessment methodology is CML –IA 2012, which is the methodology required by the European EN 15978 and EN 15804 standards. The CML methodology was created by the University of Leiden in the Netherlands in 2001.

• TRACI (Used in North America)

One Click LCA supports all 6 impact categories according to the TRACI methodology. TRACI and CML report on a number of indicators with similar units however these are not equivalent.

For North American markets we use TRACI, short for “Tool for the Reduction and Assessment of Chemical and Other Environmental Impacts”, which was developed by the U.S. Environmental Protection Agency.

• PEF (EN15804+A2) (Used worldwide - except North America)

One Click LCA supports all required impact categories according to the EN15804+A2 standard (19 environmental impacts +17 reporting categories). In July 2019 a major amendment to the EN15804 standard was approved, which became mandatory in July 2022. This came with a variety of changes but most importantly changed the format of data requirements in EPDs.

Standard impact categories and units (CML/TRACI/PEF)

Global warming potential (GWP)

Global warming potential is a relative measure of how much heat a greenhouse gas traps in the atmosphere. The global warming potential is calculated in carbon dioxide equivalents meaning that the greenhouse potential of emission is given in relation to CO2. Since the residence time of gases in the atmosphere is incorporated into the calculation, a time range for the assessment is defined to be 100 years.

Method	CML	TRACI	PEF (EN15804+A2)
Unit	kgCO2-Eq	kgCO2-Eq	total kg CO2-eq fossil kg CO2-eq* biogenic kg CO2-eq LULUC kg CO2-eq

*In selected Carbon (GWP) only tools, GWP-FOSSIL from A2 can be used as the GWP indicator.

Ozone depletion potential (ODP)

Ozone depletion potential represents a relative value that indicates the potential of a substance to destroy ozone gas as compared with the potential of chlorofluorocarbon-11 which is assigned a reference value of 1, resulting in an equilibrium state of total ozone reduction.

Method	CML	TRACI	PEF (EN15804+A2)
Unit	kgCFC-11-Eq	kgCFC-11-Eq	Kg CFC 11 Eq*

*The ODP version in PEF is not compatible with the ODP version in CML.

Acidification potential (AP)

The acidification of soils and waters occurs predominantly through the transformation of air pollutants into acids, which leads to a decrease in the pH value of rainwater and fog from 5.6 and below. Acidification potential is described as the ability of certain substances to build and release H+ions and is given in sulfur dioxide equivalents.

Method	CML	TRACI	PEF (EN15804+A2)
Unit	kgSO2-Eq	kgSO2-Eq	Mol H+ Eq*

*The acidification unit in EN15804+A2 changed when comparing it to CML.

Eutrophication potential (EP)

Eutrophication is the enrichment of nutrients in a certain place. It can be aquatic or terrestrial. All emissions of N and P to air, water, and soil and of organic matter to water are aggregated into a single measure.

Method	CML	TRACI	PEF (EN15804+A2)
Unit	kgPO4-Eq	kgN-Eq	Terrestrial - Mol N Eq Marine - Kg N Eq Freshwater - Kg Pe.*

*Under EN15804+A2 the Eutrophication potential indicator has split into three separate indicators.

Photochemical Ozone Creation Potential (POCP)/ Smog formation

Radiation from the sun produces aggressive reaction products, like ozone, in the presence of nitrogen oxides and hydrocarbons.

In the CML and PEF methodologies, this is called Photochemical ozone creation potential (POCP). In the TRACI methodology, this is called Smog formation.

Method	CML	TRACI	PEF (EN15804+A2)
Unit	kgC2H4-Eq (ethylene-equivalents)	kgO3Eq substance	Kg NMVOC nt*

*Photochemical Ozone Depletion Potential is calculated according to a different method when compared to CML.

Abiotic depletion potential (ADP)/ Fossil fuel depletion

Abiotic depletion describes the reduction of the global amount of non-renewable raw materials and is determined for each extraction of minerals and fossil fuels based on the remaining reserves and rate of extraction.

Method	CML	TRACI	PEF (EN15804+A2)
Unit	Antimony kg Sb-eq or in MJ	MJ which includes the fossil energy carriers (crude oil, natural gas, coal resources).	kg Sb-eq or MJ

Additional Indicators that are supported

All Impact Assessment Categories report on more indicators than are commonly found in calculation tools. For the majority of certifications, regulations, and schemes not all indicators are required. CML, TRACI, and PEF all report on additional indicators which are supported in selected tools. Do note that some of these indicators are not mandatory to report on and thus not all EPDs might have data for them.

Other EN standard impact categories included in One Click LCA

• Use of renewable primary energy excluding renewable primary energy resources used as raw materials (MJ net calorific value)
• Use of renewable primary energy resources used as raw materials (MJ net calorific value)
• Total use of renewable primary energy resources (primary energy and primary energy resources used as materials) (MJ net calorific value)
• Use of non-renewable primary energy excluding non-renewable primary energy resources used as raw materials (MJ net calorific value)
• Use of non-renewable primary energy resources used as raw materials (MJ net calorific value)
• Total use of non-renewable primary energy resources (primary energy and primary energy resources used as materials) (MJ net calorific value)
• Use of secondary material (kg)
• Use of renewable secondary fuels (MJ net calorific value)
• Use of non-renewable secondary fuels (MJ net calorific value)
• Net use of freshwater (m3)
• Hazardous waste disposed of* (kg)
• Non-hazardous waste disposed of (kg)
• Radioactive waste disposed of (kg)
• Components for re-use (kg)
• Materials for recycling (kg)
• Materials for energy recovery (kg)
• Exported energy (MJ per energy carrier)

Additional TRACI indicators

Used in TRACI methodology only, these focus on covering those chemicals of concern within the US (e.g., TRI chemicals). It has since been recognized that today’s global economy often requires the inclusion of suppliers who are outside of the US within countries that may have their own lists of reportable chemicals. Additional indicators are: 

• Human health cancer (CTUcancer/kg)
• Human health noncancer (CTUnoncancer/kg)
• Human health criteria pollutants 
• Eco-toxicity (CTUeco/kg)

The USEtox expanded set allows this expansion into chemicals of concern globally. USEtox is developed with two spatial scales: continental and global. The environmental compartments within the continental scale include urban air, rural air, agricultural soil, industrial soil, freshwater, and coastal marine water. USEtox includes most of the pathways found in the original EPA Risk Assessment Guidelines, including inhalation, ingestion of drinking water, produce, meat, milk, freshwater, and marine fish.

The recommended units for the USEtox human health cancer, noncancer, and ecotoxicity are CTUcancer/kg, CTUnoncancer/kg, and CTUeco/kg, respectively. Read more here.

Additional PEF (EN15804+A2) indicators

All required indicators for EN15804+A2 are supported however outside of the product LCA suite of tools, these are not utilized as of today in building or infrastructure assessments.