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Spray roof and walls of your home in white to save your life, exposed to extreme 2023 heatwaves
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On Sun, 16 Jul 2023 13:07:55 -0700 (PDT), a a <mant...@gmail.com
wrote:
Spray roof and walls of your home in white to save your life, exposed to extreme 2023 heatwaves
Roof yes, but interior walls?
We drove down from the Sierra crest yesterday. It was 82F at 7200
feet, 100F at 1000\' (easy to remember), peaked at 109 near Sacramento,
and was 68 at home on the coast.
The hottest bit was a newly-paved, flat black strip of I80. Older
freeway lanes tend to be grey.
Spray roof and walls of your home in white to save your life, exposed to extreme 2023 heatwaves
On Sun, 16 Jul 2023 13:07:55 -0700 (PDT), a a <mant...@gmail.com
wrote:
Spray roof and walls of your home in white to save your life, exposed to extreme 2023 heatwaves
Roof yes, but interior walls?
We drove down from the Sierra crest yesterday. It was 82F at 7200
feet, 100F at 1000\' (easy to remember), peaked at 109 near Sacramento,
and was 68 at home on the coast.
The hottest bit was a newly-paved, flat black strip of I80. Older
freeway lanes tend to be grey.
On Sunday, 16 July 2023 at 21:52:32 UTC+1, John Larkin wrote:
On Sun, 16 Jul 2023 13:07:55 -0700 (PDT), a a <mant...@gmail.com
wrote:
Spray roof and walls of your home in white to save your life, exposed to extreme 2023 heatwaves
Roof yes, but interior walls?
We drove down from the Sierra crest yesterday. It was 82F at 7200
feet, 100F at 1000\' (easy to remember), peaked at 109 near Sacramento,
and was 68 at home on the coast.
The hottest bit was a newly-paved, flat black strip of I80. Older
freeway lanes tend to be grey.
White isn\'t necessarily the right colour. I\'ve seen yellow paint be cooler in direct than the white it was next to. The eye doesn\'t see how paint behaves in IR, which is where a lot of the sun\'s heating energy is.
On Sunday, 16 July 2023 at 21:52:32 UTC+1, John Larkin wrote:
On Sun, 16 Jul 2023 13:07:55 -0700 (PDT), a a <mant...@gmail.com
wrote:
Spray roof and walls of your home in white to save your life,
exposed to extreme 2023 heatwaves
Roof yes, but interior walls?
We drove down from the Sierra crest yesterday. It was 82F at 7200
feet, 100F at 1000\' (easy to remember), peaked at 109 near
Sacramento, and was 68 at home on the coast.
The hottest bit was a newly-paved, flat black strip of I80. Older
freeway lanes tend to be grey.
White isn\'t necessarily the right colour. I\'ve seen yellow paint be
cooler in direct than the white it was next to. The eye doesn\'t see
how paint behaves in IR, which is where a lot of the sun\'s heating
energy is.
Pointless painting the interior walls white. But it can make sense to cover
them with a thin insulating layer and a mirror finish though. The stuff sold
for putting behind radiators is ideal for this.
That is most unlikely. Pigment white paints have always been the solution for
passively cooled observatory domes with the whitest white that money could buy
used in the old days before air conditioning.
These days they use a grey mixed silver aluminium and white paint which
reflects slightly more sunlight and is warmer to touch but crucially when it is
dark does not radiate heat away like a black body.
White paint is a pretty good approximation to a black body in the thermal band.
They used to have a lot of problems with dome seeing before they adopted the
new generation of specialist dome paints since the dome surface would supercool
overnight facing the clear night sky and drip cold dense air into the telescope
enclosure.
Now it stays at roughly the same temperature as the air - metallic
grains of aluminium paint being very poor radiators.
These days you can get designer metamaterials that are cooler than the ambient
temperature when placed in direct sunlight. Just how well they last up in real
cooling applications remains to be seen.