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Insulation Hub → Methodology
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Methodology — every number, derivable

This hub is a computed reference, and computed references owe you their assumptions. Here they all are.

The physics

Cylindrical (pipes): bare Q/L = h·π·D·ΔT; insulated Q/L = ΔT / [ ln(r₂/r₁)/(2πk) + 1/(h·π·D₂) ]; surface temperature T_s = T_amb + Q·R_surf. Flat: q = ΔT/(t/k + 1/h). Combined outer coefficient h = 10 W/m²·K — the still-air convection+radiation value used by the public calculator; wind raises it (and bare losses) substantially, so outdoor bare components waste MORE than these tables show.

λ at mean temperature

Conductivity is interpolated linearly within each material's published curve at T_mean=(T_hot+20)/2. This is the single most common error in insulation arithmetic done by hand — ambient λ understates hot-service λ by 2–3× for fibrous materials.

Economics

AssumptionValueNote
Fuel price€0.05/kWhillustrative; restate with your contract price
Operating hours8000 h/yrcontinuous process typical
Boiler efficiency82%fuel saved = heat saved ÷ efficiency
Emission factor0.183 kg CO2e/kWhnatural gas, UK DESNZ 2024
Carbon price€77.4/tEU ETS, updated via the Carbon Hub live feed

What this is not

Not a design calculation to contract: no wind, orientation or emissivity iteration, no product-specific λD, no tolerance stack. For that, run full C680/ISO 12241 with project conditions — or start from the free calculator, which exposes all inputs.

FAQ

Questions on this topic

How are the heat-loss figures on this site computed?
Steady-state 1-D conduction per ASTM C680/ISO 12241 simplified: cylindrical bare loss q=h·π·D·ΔT; insulated q=ΔT/[ln(r2/r1)/(2πk)+1/(h·π·D2)] with combined outer coefficient h=10 W/m²·K (still air) and λ interpolated at mean temperature from published product curves. Identical engine to the free calculator at /calc/.
Where do the material λ values come from?
Typical published datasheet values per material class (named on each material page alongside the governing standard, e.g. ASTM C547 grades, EN 14303 declared values). They are representative of the class, not a specific SKU — final design must use the chosen product's declared λD.
What cost assumptions are used?
€0.05/kWh fuel, 8000 operating hours/yr, 82% boiler efficiency, 0.183 kg CO2e/kWh (UK DESNZ 2024 natural-gas factor), EU ETS €77.4/t where carbon value is shown — all restated next to every table so figures can be rescaled to your prices.