Building LCA: what it is and what changes with the new UNI EN 15978
Life cycle stages and modules, building GWP and the role of EPDs: how a building LCA works and why the EPBD will make it mandatory from 2028.
A building LCA is a life cycle assessment applied to an entire building: it measures environmental impacts from the production of materials to demolition, starting with greenhouse gas emissions. The calculation method is that of UNI EN 15978, recently revised. From 2028, the European Energy Performance of Buildings Directive will make it mandatory to report the result for larger new buildings.
What a building LCA is
LCA stands for Life Cycle Assessment. Applied to a building, it adds up the impacts of all materials and all activities over a reference period, usually 50 years: extraction and production of materials, transport, construction, maintenance, energy use, demolition and disposal.
The most used result is life cycle GWP (Global Warming Potential), expressed in kg of CO₂ equivalent per square metre. It lets you distinguish two components:
- operational carbon: emissions from the energy used during operation, for heating, cooling and lighting;
- embodied carbon: emissions linked to materials and construction work, from production to end of life.
In highly efficient buildings, embodied carbon can exceed operational carbon. That is why attention is shifting from energy use to materials.
Life cycle stages and modules
The standard divides the life cycle into modules identified by a letter and a number. It is the same scheme used in environmental declarations for construction products.
| Stage | Modules | What it includes |
|---|---|---|
| Pre-construction | A0 | Activities before construction, such as surveys and preliminary demolition |
| Product | A1-A3 | Raw material extraction, transport to the factory, manufacturing |
| Construction | A4-A5 | Transport to site and construction work |
| Use | B1-B7 | Use, maintenance, repair, replacement, refurbishment, operational energy and water |
| User activities | B8 | Building-related activities not included in modules B1-B7, such as occupant mobility |
| End of life | C1-C4 | Demolition, transport, waste processing, disposal |
| Beyond the life cycle | D1-D2 | Benefits and loads of reuse, recycling and exported energy |
What changes with the new UNI EN 15978
The revision of the European standard, adopted in Italy by UNI, replaces the 2011 version. The main changes:
- new modules: A0 for pre-construction and B8 for user activities; module D is split into D1 and D2;
- indicators aligned with EN 15804+A2: the same indicators as environmental product declarations, including GWP split into fossil, biogenic and land use;
- clearer rules on scenarios, data quality and how results are reported, so that different buildings can be compared.
Why EPDs matter more
Almost all the weight of a building LCA lies in the materials data. A product-specific EPD, verified by a third party, is more accurate than an average value taken from a generic database, and with the revision its indicators are the same as the building’s.
This has two practical consequences. For designers, choosing products with EPDs makes the calculation more reliable and allows alternative solutions to be compared. For manufacturers, an up-to-date EPD becomes a commercial advantage, reinforced by the obligation to declare GWP introduced by the new Construction Products Regulation.
The upcoming obligation under the EPBD
Directive (EU) 2024/1275 on the energy performance of buildings, known as the EPBD, requires the life cycle GWP of new buildings to be calculated and shown in the energy performance certificate:
- from 1 January 2028 for new buildings with a useful floor area above 1,000 m²;
- from 1 January 2030 for all new buildings.
Member States must also set out a roadmap for introducing limit values for the GWP of new buildings. In December 2025 the Commission published the common calculation framework, based on EN 15978. LCA is already required by voluntary rating systems such as LEED and rewarded by the Minimum Environmental Criteria (CAM) for construction.
How to set up a building LCA
- Define goal and boundaries: the building, the modules included and the reference period.
- Take material quantities from the bill of quantities or the BIM model.
- Assign environmental data, preferring specific EPDs to generic values.
- Build the scenarios for maintenance, replacement, energy use and end of life.
- Calculate and identify hotspots: often a few materials, such as concrete, steel and insulation, account for most of the impact.
- Document and verify the results, especially if they are needed for tenders, certifications or financing.
A building LCA measures the impacts of a building over its entire life cycle, using the UNI EN 15978 method. The revision adds new modules and aligns the indicators with those of EPDs, which become the most important data source. From 2028, life cycle GWP will be included in the energy performance certificate of new buildings above 1,000 m².
