Whole Life Carbon Assessment Methodology
Overview
The 2050 Materials Projects tool calculates the embodied carbon of a building or project across its life cycle. Our methodology aligns with RICS Whole Life Carbon Assessment for the Built Environment, 2nd edition (RICS WLCA V2) and the underlying EN 15978 framework. This document describes the calculations performed, the inputs we use, and the assumptions made where the standard leaves a methodological choice to the assessor.
The aim is twofold: to make our results comparable with assessments produced under RICS V2, and to make the assumptions transparent so that you can reproduce or challenge any number in the report.
1. Scope and standards
Primary standard
RICS Whole Life Carbon Assessment for the Built Environment, 2nd edition
Underlying framework
EN 15978 (and EN 15804 at product level)
Units
kg CO₂e (carbon), with full GWP-total reporting; biogenic, LULUC, and other VIA categories shown separately
Reference study period
The project's design life (default 60 years if not set)
Functional unit
The whole project, with per-element reporting in the project's chosen units
In scope (embodied carbon, modules A–C):
A1–A3 Product stage (raw materials, transport to factory, manufacturing)
A4 Transport to site
A5 Construction / installation
B1–B5 Use stage (use, maintenance, repair, replacement, refurbishment)
C1–C4 End-of-life stage (deconstruction, transport, waste processing, disposal)
Reported separately (not summed into the embodied total):
Module D Benefits and loads beyond the system boundary (e.g. recycling credits)
Out of scope:
B6 Operational energy
B7 Operational water
B6 and B7 sit outside the embodied scope reported by the headline figure. Where an EPD aggregates B1–B7 into a single value, we read the B1–B5 modules individually so that operational impacts cannot leak into embodied carbon.
2. Inputs the tool needs
Element list
User-entered material configuration
Each row carries a quantity and a unit
Project life expectancy
User-entered on the project
Defaults to 60 years if not specified
Project location
User-entered (lat / lng)
Used for A4 distance calculations when products have a manufacturing location
Include transport flag
Per-project toggle
Controls whether A4 and C2 are computed; otherwise both are zero
Product or material assignment per row
EPD product, generic material, or both
See data hierarchy below
3. Data hierarchy: EPD-first, generic fallback
For every element row, the tool computes results in up to three views:
Product view — uses the assigned EPD product's published values.
Material view — uses generic material averages from our internal database (industry averages by material type and region).
Product-first view — uses the EPD where available; falls back to generic material data when no EPD is assigned. This is the default headline view.
This mirrors the RICS WLCA V2 guidance to use specific (verified) data where available, with conservative generic data as a fallback. The dashboard makes the data source per row visible so you can see how much of your total is EPD-backed versus modelled from averages.
4. How each life-cycle stage is calculated
4.1 A1–A3 — Product stage
Per element:
The per-unit factor comes from the EPD (product view) or the generic material database (material view). Where the EPD's declared unit differs from the project's unit, the tool converts using the product's declared mass / area / volume properties (e.g. m³ → m² via thickness, m² → kg via grammage, m³ → kg via density).
Individual A1, A2, A3 modules are reported when the underlying EPD publishes them; otherwise the grouped A1–A3 figure is shown.
4.2 A4 — Transport to site
A4 is only included when the project has transport emissions enabled.
For each element with mass-based units (kg, m², m³), A4 is computed from first principles:
Transported mass — quantity in kg (kg directly, m² × grammage, m³ × density).
Distance — haversine distance between the product's manufacturing location and the project site, when both are known. Default haul distance is 100 km when a location is missing.
DEFRA factor —
0.000164760348584kg CO₂e per kg·km, taken from the UK Government / DEFRA conversion factors for HGV Rigid > 7.5–17 t (average load).
For elements declared in non-mass units (piece, m, unit, etc.) — for example luminaires — the tool falls back to the EPD's declared per-unit A4 value multiplied by quantity, so that the EPD's A4 contribution is not silently dropped.
4.3 A5 — Construction and installation
Site activities, installation losses, and construction waste are taken from the EPD's declared A5 value. Where the EPD does not publish A5, A5 is zero for that element.
4.4 B1–B3, B5 — Use, maintenance, repair, refurbishment
These stages are taken from the EPD's published use-stage data, excluding replacement (B4), which is modelled at project level — see below.
4.5 B4 — Replacement (RICS V2 modelling)
Replacement is modelled at project level, not lifted from the EPD. When an EPD declares a B4 value, it is suppressed and replaced by the project's replacement bundle. This ensures that the replacement count is consistent with your building life rather than the assumed reference service life baked into the EPD.
For each element:
We use ceiling, not floor: a partial replacement period still triggers a replacement event, in line with conservative RICS V2 practice.
The B4 carbon for that element is then:
In other words, each replacement re-incurs the full embodied cost of producing, delivering, installing, and disposing of one unit of the product, minus the B-stage costs (which the original product still carries).
Where this differs from a "lifespan ratio" approach. Some tools handle short-lived products by inflating A1–A5 and C1–C4 by a uniform factor (e.g. ×3 for a 20-year product in a 60-year building). Under RICS V2, upfront carbon (A1–A5) must reflect the initial installation only — not subsequent replacements — because designers and procurement teams take decisions on the basis of upfront carbon. The total life-cycle figure is the same; what differs is the stage allocation. We follow the RICS V2 stage allocation: A1–A5 stays at 1× initial install, and replacements are reported in B4.
4.6 C1–C4 — End of life
C1, C3, and C4 come from the EPD's published end-of-life data. C2 (transport at end of life) is computed by the tool using a default disposal haul of 50 km × the DEFRA factor, and is folded into the C1–C4 group total. Individual C-stage modules are reported when the EPD publishes them.
4.7 Module D — Benefits beyond system boundary
Module D is computed where the EPD publishes it (e.g. recycling credits, energy recovery) and is reported separately. It is intentionally excluded from the headline embodied total, in line with EN 15978 and RICS V2 practice, so that benefits beyond the building's system boundary do not net off against the carbon actually emitted to deliver the project.
5. The headline number
The whole-life embodied carbon reported on the dashboard is:
Module D is shown alongside but not added to this total.
6. Reporting outputs
Every project produces:
A dashboard with the headline whole-life total and a per-stage breakdown (grouped A1–A3, A4, A5, B1–B5, C1–C4, plus individual modules where the underlying data is detailed enough).
An Excel export with one row per element × stage, showing quantities, units, the data source (EPD or generic), and the contribution of each module to the project total. The Excel export is the source of truth for any downstream reporting.
An impact matrix covering global warming potential plus additional VIA categories where available (e.g. biogenic carbon, land-use change, non-hazardous waste, fossil resource depletion).
7. Assumptions and limitations
Generic materials are industry averages and carry higher uncertainty than EPD-backed values. The tool flags how much of your total is generic vs. EPD-backed.
Transport distance defaults to 100 km when a manufacturing location is missing. If precise sourcing matters for your assessment, set the manufacturing location on each product.
Mode of transport is assumed to be HGV (DEFRA Rigid > 7.5–17 t average load). Sea, rail, and air freight are not currently modelled separately.
A5 site activities rely on the EPD's published A5 value. Project-level construction waste percentages are not yet modelled separately on top of EPD A5.
Operational carbon (B6, B7) is out of scope; pair this assessment with an operational energy model for a full whole-life view.
Module D is informative only and is not netted against embodied totals.
8. Reproducibility
For any number in the dashboard, the per-element Excel export shows the inputs (quantity, unit, EPD or generic source, stage factors, distance) and the resulting per-stage contribution. Two configurations of the same project, run with the same inputs, will produce identical totals.
If you need to verify a specific row against an EPD or a published figure, the per-element breakdown is the place to start.
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