Painted white roof drops house temps 8-10 degrees - Page 2

vinzmane123 · 04-09-11, 05:15 AM

Its not so hot in your house if you paint it white. I think it is really cool and very neatly to an eyes.

ThatSolarGuy · 04-12-11, 02:54 AM

When I was installing my own solar system last July I took a laser pointer thermometer gauge thingy up the ladder with me and started pointing it a various surfaces. I have a picture of the thermometer pointing at my medium grey flat concrete roof tile and the number 165 is reading on the gauge!! My feet weren't tingling because of "falling asleep",.....they we're burning!! I am so going up on the roof and painting a tile or two white and reporting back to you guys on the delta of the temperature sensor.

Blue Skies,

Jeff

Xringer · 04-12-11, 08:30 PM

You might get conductive heat from nearby tiles, that makes the white tiles warmer.

When I was in Bermuda, (in the Navy) we had hills on the base that were covered
in concrete and painted bright white. Looked like many of the roofs in Bermuda.
Those white roofs and the white mountains on the base were rain catchment systems.
(There are very few fresh water wells on the island).

In the typical home, there is a little manhole in the kitchen floor.
Lift it up and find the 'basement' is a giant water tank with catfish swimming around..

Anyways, while I was there (4-15-63 to 4-15-65), it got pretty hot in the summer time.
But, inside of most homes wasn't uncomfortable, since the roof was bouncing
the sunlight away, and a concrete floor sitting on tons of cool water tends to keep it nice..

I didn't know anyone that had AC in their home..

S-F · 04-13-11, 07:24 AM

Sounds great but in mixed temperature climates it's probably not such a good idea. I can live with a hot house easier than a cold house. I can survive 90 degrees inside but 0 degrees would be difficult.

ThatSolarGuy · 04-14-11, 02:46 AM

To S-F,
So true. It's easy for us to forget that not every solution will work in EVERY place.

I like the idea of a large aquarium acting as a heat sink as my foundation. We could just sweep my daughters high-chair scraps right into a floor grate!

Imagine where our building codes would be if we didn't have several decades of relatively cheap fossil fuels. In the SW roofs might be mandated to be white, and every roof would have 500ft2 of south facing pitch w/o chimneys and soil pipes for solar retro-fit, maybe even conduit stubbed out.

Painting surfaces white in hot climates and dark colors in cold climates is ancient technology that was lost in this country. My only concern with painting my roof white is (current) cultural unacceptance. Who knows, maybe I'll be a trend-setter on the block!

I'll let you know when I paint the tiles the temp delta. I'm going to do more than a few adjacent tiles to thwart conductive transfer.

Xringer · 04-14-11, 07:50 AM

"cultural unacceptance".. That's kinda what I got from my wife before we had
the roofers come in and remove/replace the old shingles.

I wanted to paint the roof with some weather-proof stuff, with white roofing paint over it.
"Nope, that wouldn't look like all the other roofs on the street"..

But, I kinda get my way for a while, every winter..

tomboy mom · 07-04-11, 04:56 PM

Quote:

Originally Posted by tasdbois

Interesting. I wonder how less visually intrusive alternatives compare. Say a radiant barrier with increased attic airflow.

i have added radiant barriers to both my attics. omg. talk about work! it all sounds good until you're sliding through an attic with a flashlight in your hand, a mask on your face and a backpack full of stapling supplies and attempting to pull and kick an unruly roll of radiant barrier through while balancing on the 2x4's. (word to the wise--take a phone in case you need to ask for something.)

did it help? YES! absolutely had more impact on temperature than anything else short term.

we don't need need to turn on central air until the outside temperature is about 105--closer to 110 if we have done everything perfectly that day. without the radiant barrier i don't think that would be possible.

however, if painting the roof white would be as effective i would gladly do that instead and not really care about what it looks like.

tomboy mom · 07-04-11, 05:03 PM

Quote:

Originally Posted by ThatSolarGuy

I'm going to do more than a few adjacent tiles to thwart conductive transfer.

I could be misunderstanding here, but I'm not sure conductive transfer applies in this situation. When I installed reflective I did it over 3 years without worrying about full coverage. Unlike insulation, reflective methods work independently adjacent areas.

Daox · 07-05-11, 10:58 AM

Painting the roof would still be a good idea and would help. It will still get hot and the radiant barrier will still help once the roof has heated up.

Xringer · 07-05-11, 08:43 PM

I wonder how many BTUh are absorbed by dark colored roof shingles,
as compared to shingles that had a bright white coat of paint.?.

My guess is, the painted roof would not be re-radiating heat inside (under the roof)
at anywhere near the rate of the dark roof.

One web hit on the topic..
Energy Efficiency Delivered by “Cool Roof” Reflectivity - Cool Zone - Duro-Last Roofing, Inc.

04-09-11, 05:15 AM	#11
vinzmane123 Lurking Renovator Join Date: Apr 2011 Location: Madison Avenue Posts: 1 Thanks: 0 Thanked 0 Times in 0 Posts	hi Its not so hot in your house if you paint it white. I think it is really cool and very neatly to an eyes. __________________ Sorry, new users are not permitted to post links in their signatures.

04-14-11, 02:46 AM	#15
ThatSolarGuy Lurking Renovator Join Date: Apr 2011 Location: Murrieta California Posts: 3 Thanks: 0 Thanked 1 Time in 1 Post	Energy solutions need geographic concern To S-F, So true. It's easy for us to forget that not every solution will work in EVERY place. I like the idea of a large aquarium acting as a heat sink as my foundation. We could just sweep my daughters high-chair scraps right into a floor grate! Imagine where our building codes would be if we didn't have several decades of relatively cheap fossil fuels. In the SW roofs might be mandated to be white, and every roof would have 500ft2 of south facing pitch w/o chimneys and soil pipes for solar retro-fit, maybe even conduit stubbed out. Painting surfaces white in hot climates and dark colors in cold climates is ancient technology that was lost in this country. My only concern with painting my roof white is (current) cultural unacceptance. Who knows, maybe I'll be a trend-setter on the block! I'll let you know when I paint the tiles the temp delta. I'm going to do more than a few adjacent tiles to thwart conductive transfer.

07-05-11, 10:58 AM	#19
Daox Administrator Join Date: Aug 2008 Location: Germantown, WI Posts: 5,525 Thanks: 1,162 Thanked 374 Times in 305 Posts	Painting the roof would still be a good idea and would help. It will still get hot and the radiant barrier will still help once the roof has heated up. __________________ Current project - To view links or images in signatures your post count must be 0 or greater. You currently have 0 posts. To view links or images in signatures your post count must be 0 or greater. You currently have 0 posts. & To view links or images in signatures your post count must be 0 or greater. You currently have 0 posts.

04-12-11, 02:54 AM	#12
ThatSolarGuy Lurking Renovator Join Date: Apr 2011 Location: Murrieta California Posts: 3 Thanks: 0 Thanked 1 Time in 1 Post	When I was installing my own solar system last July I took a laser pointer thermometer gauge thingy up the ladder with me and started pointing it a various surfaces. I have a picture of the thermometer pointing at my medium grey flat concrete roof tile and the number 165 is reading on the gauge!! My feet weren't tingling because of "falling asleep",.....they we're burning!! I am so going up on the roof and painting a tile or two white and reporting back to you guys on the delta of the temperature sensor. Blue Skies, Jeff

04-12-11, 08:30 PM	#13
Xringer Lex Parsimoniae Join Date: Feb 2009 Location: Woburn, MA Posts: 4,918 Thanks: 114 Thanked 250 Times in 230 Posts	You might get conductive heat from nearby tiles, that makes the white tiles warmer. When I was in Bermuda, (in the Navy) we had hills on the base that were covered in concrete and painted bright white. Looked like many of the roofs in Bermuda. Those white roofs and the white mountains on the base were rain catchment systems. (There are very few fresh water wells on the island). In the typical home, there is a little manhole in the kitchen floor. Lift it up and find the 'basement' is a giant water tank with catfish swimming around.. Anyways, while I was there (4-15-63 to 4-15-65), it got pretty hot in the summer time. But, inside of most homes wasn't uncomfortable, since the roof was bouncing the sunlight away, and a concrete floor sitting on tons of cool water tends to keep it nice.. I didn't know anyone that had AC in their home..

04-13-11, 07:24 AM	#14
S-F You Ain't Me Join Date: Nov 2009 Location: Northampton MA Posts: 662 Thanks: 6 Thanked 71 Times in 58 Posts	Sounds great but in mixed temperature climates it's probably not such a good idea. I can live with a hot house easier than a cold house. I can survive 90 degrees inside but 0 degrees would be difficult.

04-14-11, 07:50 AM	#16
Xringer Lex Parsimoniae Join Date: Feb 2009 Location: Woburn, MA Posts: 4,918 Thanks: 114 Thanked 250 Times in 230 Posts	"cultural unacceptance".. That's kinda what I got from my wife before we had the roofers come in and remove/replace the old shingles. I wanted to paint the roof with some weather-proof stuff, with white roofing paint over it. "Nope, that wouldn't look like all the other roofs on the street".. But, I kinda get my way for a while, every winter..

07-05-11, 08:43 PM	#20
Xringer Lex Parsimoniae Join Date: Feb 2009 Location: Woburn, MA Posts: 4,918 Thanks: 114 Thanked 250 Times in 230 Posts	I wonder how many BTUh are absorbed by dark colored roof shingles, as compared to shingles that had a bright white coat of paint.?. My guess is, the painted roof would not be re-radiating heat inside (under the roof) at anywhere near the rate of the dark roof. One web hit on the topic.. Energy Efficiency Delivered by “Cool Roof” Reflectivity - Cool Zone - Duro-Last Roofing, Inc.