Whole-building LCA: LEED v4, BREEAM, DGNB, and RE2020 compared (2026)

A whole-building LCA (WBLCA) prepared for LEED v4 and one prepared for a European scheme can give different numbers for the same building, because each scheme sets its own scope, study period and unit. LEED v4 BD+C Option 4 assesses the structure and enclosure over a service life of at least 60 years. RE2020, Denmark’s BR18 and the EPBD use a 50-year period with their own scope. Neither figure is wrong, and the two cannot be compared directly. Always state the scheme, module scope, period and unit beside every carbon figure.

Key facts at a glance

Sources: LEED v4 BD+C Reference Guide (MR credit, Option 4); One Click LCA BREEAM UK NC 2018 LCA credits guide; Guide RE2020 (Icconstruction table, 50-year period); One Click LCA description of Denmark BR18; Directive (EU) 2024/1275 Article 7(2) and Delegated Regulation (EU) 2026/52, Annex III.

What is a whole-building LCA and what standards govern the calculation?

A whole-building life-cycle assessment (WBLCA) adds up the environmental impact of a complete building across its life stages. In Europe the building-level method is EN 15978 (ISO 21931-1 is the international counterpart). EN 15978 organizes impacts into modules A1 to A5 (product and construction), B1 to B7 (use stage), C1 to C4 (end of life) and D (benefits and loads beyond the system boundary). Which modules, which indicators and which floor-area unit apply is set by the scheme or regulation, not by EN 15978 alone. A product EPD reports the impact of a declared unit of one product; a WBLCA combines product data from EPDs, weighted by the quantities in the BIM model and by the replacement cycles over the study period. For more on the method see EN 15978 explained, and for the product data see what is an EPD.

What does each scheme assess?

LEED v4 BD+C Option 4 assesses the project’s structure and enclosure. The baseline and proposed buildings must have comparable size, function, orientation and operating energy performance, the same service life of at least 60 years, and the same LCA software and data sets, and the data sets must comply with ISO 14044.

France’s RE2020 regulates two climate indicators: Icconstruction, the climate impact of construction products and equipment and their installation, and Icénergie, the climate impact of energy used over the building’s life. Both are calculated over 50 years in kg CO₂e per m² of habitable floor area or useful floor area. Icconstruction has a maximum value that depends on the building use and tightens in steps from 2022 to 2031.

Denmark’s BR18 limit applies to new buildings above 1,000 m². One Click LCA’s description of the BR18 calculation lists modules A1 to A3, B4, B6, C3, C4 and D as reported, over a 50-year period.

For BREEAM Mat 01 and DGNB ENV 1.1, take scope, study period and benchmark values from the current scheme manual or criteria for the version you are certifying under, since those documents change between versions.

The EPBD Annex III scope is in Table 2: modules A1 to A5, B1 to B4, B6, C1 to C4 and D are required, and B5, B7 and B8 are optional.

What reduction does each scheme require?

LEED v4 BD+C Option 4 requires at least a 10% reduction against a baseline building in at least three of the six impact categories, one of which must be global warming potential. No impact category may increase by more than 5%. The option earns 3 points.

LEED v4.1 changed the credit into tiers. According to CaGBC’s summary, a path for performing an LCA regardless of the results earns 1 point, a 5% reduction in three of six categories including GWP earns 2 points, the v4 requirement (10%) earns 3 points, and a 10% reduction in two categories with a 20% reduction in GWP plus reuse or salvaged material earns 4 points. Confirm the tiers in the current LEED v4.1 credit text.

BREEAM UK NC 2018 Mat 01 awards credits for reductions in life-cycle impact, up to 7 plus 3 exemplary-level credits according to One Click LCA’s guide. Check the manual for the version in use.

RE2020 applies phased maximum values as a regulation. The EPBD requires disclosure only; Member States may set limits.

What are the six impact categories LEED v4 lists?

LEED v4 BD+C Option 4 lists six impact categories, from which at least three must show the reduction:

• global warming potential (greenhouse gases), in kg CO₂e
• depletion of the stratospheric ozone layer, in kg CFC-11
• acidification of land and water sources, in moles H⁺ or kg SO₂
• eutrophication, in kg nitrogen or kg phosphate
• formation of tropospheric ozone, in kg NOx, kg O₃ eq or kg ethene
• depletion of nonrenewable energy resources, in MJ

All six must be reported. EN 15804+A2 EPDs declare 13 core indicators, which cover these themes in a different form; see EN 15804+A2 explained. Match the EPD indicator to the category named by the scheme.

Which tools support these schemes?

Tool acceptance is scheme-specific and changes. Check each scheme’s current list of accepted tools and datasets rather than assuming that one tool is accepted everywhere. Denmark’s LCAbyg is the national tool for BR18, and France’s RE2020 uses the INIES database. Software vendors’ own claims of approval across schemes should be confirmed with the scheme.

Which WBLCA mistakes should you avoid?

1. Comparing results across schemes directly. A LEED structure-and-enclosure figure and a figure for another scope or period describe different things. State the module scope, period and scheme beside every carbon figure.

2. Running a WBLCA only at design completion. A WBLCA run after construction documents are issued cannot drive material substitutions. Run it at schematic design to find carbon hot spots, refine it through design development and finalise it at submittal.

3. Adding module D without checking the scheme. Module D shows benefits and loads beyond the system boundary and is reported separately in EN 15978. Whether a scheme counts it toward a reduction or limit differs; read the scheme text before including it.

4. Using generic data when product-specific data exists. Generic datasets are conservative stand-ins. Replace them with product-specific EPDs as products are selected, and check how the scheme treats each data type.

Frequently asked questions

What is the difference between LEED v4 and LEED v4.1 WBLCA requirements?

LEED v4 BD+C Option 4 requires at least a 10% reduction in at least three of six impact categories, one of which must be GWP, with no category rising by more than 5%, for 3 points. LEED v4.1 adds tiers; according to CaGBC’s summary they run from 1 point for performing an LCA to 4 points for a larger GWP reduction combined with reuse. Check the current LEED v4.1 credit text.

Can a WBLCA done for another scheme satisfy LEED v4?

Only if its scope, period and data meet the LEED requirements. LEED v4 Option 4 assesses structure and enclosure, requires a baseline building and the same tools and data sets for both models, and requires a service life of at least 60 years. A study with a different study period or scope needs re-running or adjusting to the LEED rules.

Is a WBLCA required for DGNB certification?

DGNB treats the life-cycle assessment as criterion ENV 1.1. Check the current DGNB criteria for the system and version you are certifying under for whether and how the criterion is required.

What is Denmark’s whole-building carbon limit?

Denmark’s BR18 sets 12 kgCO₂e/m²/yr for new buildings above 1,000 m², with stricter values phased in from July 2025; see whole-life carbon rules by country.

What does the EPBD require for whole-life carbon?

Article 7(2) of Directive (EU) 2024/1275 requires disclosure of life-cycle GWP in the energy performance certificate, not a limit; the dates and scope are in EPBD 2028 architect requirements.