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Methodology

How the calculator decides, and what it does not.

The Fabrick calculator is a comparison tool, not a verdict. It ranks materials by embodied carbon and surfaces the trade-offs (thermal performance, fire rating, indicative cost) so a specifier can choose what matters most for the build in front of them.

What we measure

  • Embodied carbon (kgCO₂e/kg). From the ICE Database (Inventory of Carbon and Energy) by Circular Ecology, version 3.0. Modules A1-A3 (cradle-to-gate) unless otherwise stated. Industry-average values; project-specific EPDs should always be preferred for design-stage decisions.
  • Thermal conductivity (λ, W/m·K). Typical declared values per BS EN 13162-13172 (mineral wool to phenolic) and BRE BR443 conventions. Used to compute the relative thickness penalty when comparing one material against another at the same U-value.
  • Fire rating (Euroclass). Reaction-to-fire classification under BS EN 13501-1. We show the headline class (A1-F) plus smoke/droplet sub-class where applicable. Treated/specified products may achieve different ratings than the generic material; check the manufacturer datasheet.
  • Cost (£ band). Indicative material cost for like-for-like quantity, banded £ to ££££ from common BCIS-derived ranges and trade pricing. Excludes labour and project-specific factors. Treat as a direction signal, not a quote.

What we do not measure

  • Operational carbon (modules B6-B7) and full life-cycle modules D (reuse/recovery). Single-figure embodied carbon is an upstream signal, not a whole-life answer.
  • Acoustic performance, moisture/vapour management, settling, workmanship and detailing risk. All matter and all influence the right specification.
  • Site availability and lead time. There is no reliable public dataset for this, and substitution decisions in practice often hinge on it.
  • Manufacturer-specific EPDs. Where a member of the Insulation Manufacturers Association or another supplier holds a product-specific EPD that beats the database average, the calculator does not currently see it. We are building a route to ingest verified EPDs.

Sources

Embodied carbon: ICE Database, Circular Ecology

Thermal conductivity: BS EN 13162-13172 declared λ, BRE BR443 typical values

Fire rating: BS EN 13501-1 reaction-to-fire classification

Cost banding: indicative ranges informed by BCIS (RICS) and live trade prices

Benchmarks: LETI 2020 targets, RIBA 2030 v2 targets, UK Net Zero Carbon Building Standard (UKNZCBS)

Editorial position

The calculator does not promote any product or manufacturer. Recommendations are surfaced strictly on data that is published and verifiable. If you are a manufacturer with a product-specific EPD that improves on a database value used here, get in touch at hello@fabrick.agency. Verified EPDs improve accuracy for everyone.

Last reviewed: 2026-07-14.