Whole life carbon assessment for the built environment

The Whole Life Carbon Assessment (WLCA) standard is a professional guideline published by the Royal Institution of Chartered Surveyors (RICS) in September 2023, with an updated version effective from 1 July 2024. Authored by a multidisciplinary team—including Simon Sturgis, Jane Anderson, Paul Astle and others—the document sets out a mandatory methodology for measuring and reporting carbon impacts of buildings and infrastructure throughout their life cycles. It aligns with European standards EN 15978, EN 17472 and EN 15804, and is intended for use by RICS members, architects, engineers and other built‑environment professionals.

The standard applies to all types of construction, from new builds and retrofits to masterplans and fit‑out projects. It covers every life‑cycle stage (modules A‑C) and also requires separate reporting of benefits and loads beyond the system boundary (module D). Specific guidance is provided for residential, commercial and infrastructure assets, with distinct reference periods (RSP) of 60 years for most projects and 120 years for large infrastructure.

Carbon data may be sourced from generic national factors, specific Environmental Product Declarations (EPDs), or collective sector datasets. Early‑design assessments rely on generic data and benchmark values (e.g., default transport distances, waste rates and construction activity factors). As design progresses, the methodology mandates the use of project‑specific EPDs where available, and outlines default contingency, carbon‑data and quantities uncertainty factors to manage risk.

• Module A (Up‑front carbon) captures raw‑material extraction, product manufacturing, transport to site and construction activities, including pre‑construction demolition (A5.1).
• Module B (In‑use carbon) covers material‑related emissions (B1), maintenance, repair, replacement (B2‑B4), refurbishment (B5), operational energy (B6), water use (B7) and user activities (B8).
• Module C (End‑of‑life) records deconstruction, waste processing, transport and final disposal. Each module requires specific calculation formulas, default values (e.g., 5 % waste for in‑situ concrete, 35 kg CO₂e /m² for demolition) and guidance on handling biogenic carbon, carbonation and refrigerant fugitive emissions.

Assessors must apply a contingency factor (15 % in early design, 6 % in technical design, 0 % post‑completion) and add carbon‑data and quantities uncertainty factors based on data quality scores. The combined percentage is added to all modules except B6‑B8 to produce the final WLCA result. Detailed reporting templates for buildings and infrastructure ensure consistent presentation of upfront, embodied, operational and whole‑life carbon figures.

The standard differentiates between fossil, biogenic and land‑use‑change carbon. Sustainably sourced timber and other biomass receive a removal credit in modules A1‑A3, balanced by emissions at end‑of‑life. It also encourages circular‑economy practices, such as reusing formwork (default three uses) and accounting for recycling or energy recovery in module D.

Two decarbonisation pathways are required: one assuming current grid emissions and another incorporating future grid decarbonisation (e.g., UK National Grid’s “fall‑short” scenario). Material‑decabonisation assumptions are also defined, with specific percentages applied to modules B5, C1‑C2 and D1 over the RSP.

The publication includes extensive appendices covering metadata, acknowledgements, detailed material specifications, default transport scenarios, waste rates, carbon‑data quality matrices and guidance on using BIM, CIBSE TM65 and other tools. Links to the full PDF and additional RICS resources are provided for deeper exploration.

For a pan‑European audience focused on sustainable housing, this standard offers a harmonised, rigorous framework to quantify and compare carbon performance across diverse building typologies and regulatory contexts. By mandating full‑life‑cycle accounting, uncertainty transparency and alignment with EU‑wide standards, it supports the development of low‑carbon homes, facilitates benchmarking, and underpins policy targets such as the EU’s Renovation Wave and net‑zero building goals.