Screen early options
Use indicative inputs to identify material, energy, transport, and lifecycle hotspots before detailed data collection begins.
Methodology
Transparent screening methodology for early carbon decisions.
A practical framework for preliminary product carbon footprint and construction whole-life GWP estimates. It supports early decisions and does not replace a verified EPD or formal LCA.
What these estimates are designed to do
Make assumptions visible
Record functional units, quantities, factors, boundaries, and exclusions so results can be reviewed and improved.
Prepare for formal work
Use screening results to focus supplier engagement, data requests, scenario testing, and the scope of a future LCA or EPD.
Emission-factor sources
Screening factors should be selected from credible, traceable sources appropriate to the geography, technology, material, and reporting period of the estimate.
Supplier-specific data
Preferred where available and sufficiently documented, including product declarations, verified supplier inventories, and energy or transport records.
Published EPDs and LCA datasets
Use relevant, current declarations and recognized lifecycle inventory datasets where the product, region, and declared unit are comparable.
Government and industry datasets
Use transparent national, European, or sector datasets for electricity, fuels, freight, and generic materials when primary data is unavailable.
Documented proxy factors
Use conservative proxies only when better data is not available, clearly flagging the source, date, geography, and reason for use.
System boundaries
The calculators use declared screening boundaries. Results should only be compared when functional units, boundaries, data quality, and assumptions are aligned.
Product footprint screening
Materials
Includes the embodied impact associated with material quantities and selected material emission factors. Upstream extraction and processing are represented only to the extent covered by the chosen factor.
Manufacturing energy
Includes process energy entered for the product and the selected electricity or fuel factor. Capital equipment, employee travel, and other overheads are excluded unless explicitly added.
Transport
Includes a simplified freight estimate based on distance, load mass, and an assumed transport factor. Route, vehicle, backhaul, and load-factor assumptions must be recorded.
Construction whole-life GWP screening
Upfront carbon: A1–A5
A1–A3 are represented through material factors; A4 through transport assumptions; and A5 through construction or site activity inputs where provided.
Use stage: B6
Operational energy is represented through annual or lifetime energy assumptions and selected energy factors. Other B modules are excluded unless explicitly modeled.
End of life: C1–C4
End-of-life impacts are represented through demolition, transport, waste processing, and disposal assumptions where inputs are provided.
Allocation rules
Use physical allocation first
Where a process produces multiple products, allocate by mass, energy content, volume, or another physical relationship when it reflects the process.
Use economic allocation only when needed
If physical allocation is not feasible, use documented economic allocation with the price basis, period, and sensitivity noted.
Avoid double counting
Keep recycled content, recycling credits, co-products, and energy recovery treatment consistent with the selected dataset and boundary convention.
Keep allocation consistent
Apply the same allocation approach across compared scenarios. If methods differ, present results separately rather than as a direct comparison.
EN 15978-informed construction assumptions
Construction outputs use an EN 15978-informed screening structure. They are not a complete EN 15978 assessment unless all required modules, scenarios, data quality checks, and reporting requirements are addressed.
| Module | Stage | Screening assumption |
|---|---|---|
| A1–A3 | Product stage | Material production is estimated from quantities and selected material emission factors. |
| A4 | Transport to site | Transport is estimated from distance, mass, and freight assumptions. |
| A5 | Construction and installation | Site energy, waste, and installation impacts are included only where entered or explicitly assumed. |
| B6 | Operational energy use | Operational energy is estimated from the stated energy demand, study period, and energy factors. |
| C1–C4 | End of life | Demolition, transport, processing, and disposal are included only to the extent represented by the entered assumptions. |
Interpretation and limitations
Not a verified declaration
Calculator outputs are preliminary screening estimates and must not be presented as verified EPDs, certified LCA results, or comparative environmental claims.
Data quality drives confidence
Results are only as reliable as the input quantities, factors, geography, technology, time period, and documented assumptions.
Update before decisions are fixed
Replace generic factors with supplier-specific and project-specific data as design, procurement, and operational information becomes available.
Need a formal scope or review?
Use the advisory route to define data requirements, boundaries, allocation choices, and a credible path toward formal LCA or EPD work.