Each field on a roof record is one of three things: fetched from an open-data source, read from a static physics lookup, or computed from the two. The public dashboard now combines 12 enriched city caches with live model-only scans for new UK areas, so every card should say what is measured, modelled, estimated or assumed.
material comes from OS NGD where present, but "metal radiates at ε≈0.45" is a constant we look up (EMITT); that assumed stock-roof emittance and the measured albedo from Sentinel-2 are balanced by ASTM E1980 physics to give a roof’s modelled temperature. Sentinel-2 SCL masks cloud, shadow, snow and no-data pixels before albedo is averaged. Nothing on a card is asserted; everything traces back to a source, a cited constant, or a labelled estimate. The road heat layer is different: it is live modelled context from basemap road geometry plus Open-Meteo weather, not a roof-card field and not measured road temperature. The Radiative cooling line’s physics (the two-band sky, the ≈68 W/m² net flux, the 0.18 clear-sky duty) is reproducible in the radiative-cooling simulator.