How to read this map: start with reflectance. Orange roofs absorb more sun and are the first coating candidates; blue roofs are already cooler. Click a roof to see the evidence trail: material source, albedo band, geometry, building record, peak temperature and coating opportunity.
Material: served from Ordnance Survey NGD authoritative roof data for 91.95% of roofs (badged OS NGD, shown without a hedge). We switched to it after benchmarking our own 10 m spectral guess against it: OS matched 97% of our roofs while the guess agreed only 49% of the time. Where OS is absent, a fallback model trained on real OpenStreetMap tags across 12 UK cities fills in, and those roofs carry the “Uncertain” hedge plus the top-3 candidates.
Geometry: free 1 m LiDAR (pitch, aspect, height, form) enters as a physics plausibility constraint that re-ranks impossible material/shape combinations (it corrected 4% of materials on a held-out tile), not as a learned feature, which did not generalise to unseen cities.
Albedo: narrowband-to-broadband physics from Sentinel-2 surface reflectance, clear in-footprint pixels of the least-cloudy recent scene, with a propagated per-roof uncertainty (±0.03 to ±0.07). Sentinel-2 SCL masks cloud, shadow, snow and no-data pixels before averaging; fully masked roofs are skipped, not filled with zeros.
Thermal: peak surface temperature and SRI are modelled from the ASTM E1980 balance using measured albedo and assumed stock-roof emittance. “Surface temp now” uses live Open-Meteo irradiance, air temperature and wind; peak and SRI are standardised comparison numbers.
Savings: heat rejected and peak-temperature cut are physics on every roof. Cooling pounds use a three-tier ladder: EPC/SBEM measured where present, BEES benchmark estimated where building use implies cooling, and physics-only with no pounds where there is no cooling signal.
Not yet: live scan-any-address, in-situ ground-measured roof albedo, and measured emittance for the existing roof stock. The coating’s own optics are stronger: opaque 95% solar reflectance and 95% thermal emittance, with full cured-film characterisation in progress.