Dark asphalt roads and bitumen roofs can absorb over 90% of incoming sunlight, re-radiating it as sensible heat and pushing surface temperatures 20–30°C above air temperature on a clear summer afternoon. This is the core physics behind the urban heat island effect. Raising surface albedo (reflectivity) with light-colored "cool" roofing membranes and reflective pavement coatings, and shading streets with tree canopy, are two of the most cost-effective levers cities have to cut peak street-level temperatures.
T = T_air + (1 − albedo) × solar factor × gain constant, minus any tree-shade discount.Studies of real cool-roof and cool-pavement retrofits (e.g. Los Angeles' cool pavement pilots) have measured surface temperature drops of 10–12°C on treated streets, though air-temperature gains at pedestrian height are smaller and depend heavily on how much reflected shortwave radiation nearby building facades and people absorb instead.
A 3D city block where every rooftop and street tile is colored live by a simplified surface-energy-balance model, so you can see how albedo, tree shade, and time of day physically drive peak urban temperatures.
Surface temperature is modeled as air temperature plus a solar gain scaled by (1 − albedo), minus a shade discount from nearby tree canopy — the same first-order physics that drives real cool-roof and cool-pavement retrofits.
Drag the cool-roof, cool-pavement, and tree-canopy sliders to retrofit the city, then scrub time of day to watch the sun move and surfaces heat and cool in real time. Watch the peak street temperature and heat-mitigated stats respond.
Standard black bitumen roofing (albedo ≈ 0.2) can sit 30°C above air temperature at peak sun; certified cool roofs with albedo above 0.6 can cut that gain by more than half.