Is a dark coloured building better than a lgiht coloured one for energy usage?

The white one.

The black one is more likely to be used as an office building. The white one is more likely to be council flats, and filled with morons who leave the windows open and crank the heating up to compensate.

Reply to
Jules Richardson
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An interesting question. The dark building will gain heat more quickly, but loose heat more quickly. It will warm up in the day and cool at night.

Reply to
Giss

So if painted black on the outside to absorb heat during daylight hours but painted white inside to inhibit the transfer back out at night.

Reply to
ss

NO! It's to stop THEM from interfering with the astronaughts minds with their mind rays.

Reply to
Chris Holmes

There seem to be a number of different and sometimes very wildly conflicting views and opinions emerging, but this is not entirely unexpected :)

Is there any consensus that, at the temperatures concerned, what type of gain and loss predominates, radiation, conduction or convection?

Would it help with any assumptions if the building only needed to maintain a constant reference of 20 deg C during the period between the autumn and spring equinox?

Go further and assume very low thermal mass in the building, zero glass, and a thick uniform slab of PIR foam on all sides. Assume a constant external temperature of say 10 deg C, a constant wind speed of say 1m/s and zero cloud cover.

Maybe this is too difficult to come up with anything approaching a definitive answer (a similar question has been posed to a number of people over the past few years, some have even been sober!)

Maybe the only answer is to do it for real and fill a field with a number of widely spaced 1m sided cubes of a uniform colour ranging from black through fifty shades of grey to pure white, plus a shiny silver one, fit each one with a controllable heat source and actually monitor what really happens!

I doubt it would get funding for a science project but call it art and they may throw money at it :)

Reply to
The Other Mike

No it just makes the integrals more difficult. Average annual figures and monthly figures are available for a given latitude / location.

Under those circumstances external losses will be mostly by conduction of heat to the passing air and the colour of the outer wall will be all but irrelevant to the internal temperature which will be dominated by leakage of heat from the ground. Caves have almost constant temperature.

You don't need cubes. You can model it close enough with painted pieces of 10" square plywood placed on a think polystyrene slab with an LCD stuck on thermometer in the middle (on the back if you want to be prefectionist).

I think it has been done several times as a school science project. Aluminium foil or space blanket gives an interesting answer.

Reply to
Martin Brown

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