Solar load per room: which room gets hot in summer
Same calculation, different question. A room with too little sun in winter often has too much in summer — and on the top floor under a metal roof that is not a detail. Solar load relates the incoming sun per room to its floor area and shows which room carries the burden.
A report that only counts sunshine hours turns every south-facing flat into good news. In a city that regularly passes thirty degrees in summer, that is half the truth. So the same sheet carries both readings: in winter every hour counts, in July what counts is how long the sun presses on a small room.
Try it on one address →What is computed — and where it stops
The floor area is essential. Without it a four-square-metre bathroom would read as loudly as a thirty-square-metre living room, and the map would be blind to size.
Frequently asked
Is this a cooling-load calculation?
No. A cooling load to standard needs build-ups, U-values, shading devices and internal gains. What is here is the geometric solar gain per room — the precondition for such a calculation, not a substitute for it.
Why no temperature in degrees?
Because we cannot measure it, and an invented figure would be worse than none. A number in degrees would be read as a measurement.
Does it help me choose a flat?
It answers a question nobody asks at a viewing in winter and regrets in July: which room takes the sun. The bedroom carrying the load is a different finding from the living room carrying it.
Does it apply to a converted attic?
The calculation sees windows, not the roof surface. A conversion under an unshaded roof carries a load beyond its windows — the report says so rather than pretending to have measured it.
All measurements · For agents & developers · The light check
Geometric solar gain per room from the same sun and horizon calculation as the sunlight hours, related to floor area. Not a cooling load to standard, no temperature figure.