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Passive Cooling

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Palawan Aussie:
Frosty writes,

--- Quote ---It sounds like insulation is an after thought when building a house. What has everybodying been using to insulate the outside walls?
--- End quote ---

There's good information regarding passive-cooling here .. in fact, the whole website is excellent ..

For example, here's a simple research initiative that people might like ..  (I wouldn't use lime on an aluminium or tin roof though) (snipped)

From David: My roof needs replacing anyway, so I thought I would do an experiment to see the effects of painting it WHITE. I have already placed digital thermometers in the attic for previous experiments so I could easily monitor progress.

I started off with a product made for the purpose... a highly reflective "elastomeric" roof coating. However, a 5 gallon bucket of this product costs $60.00. I figured I needed TEN of those 5 gallon buckets to cover my 1300 square foot roof. That put the cost up around $600 dollars. TOO MUCH MONEY for a little experiment.

So I opted for the EL-CHEAPO method of using HYDRATED LIME mixed with 50% water to do the job. Two bags of Hydrated Lime cost $14.00 total!!  It is available in the concrete department of any hardware store for $7.00 per 50 pound bag. This stuff goes on kinda GRAY looking when it is wet. But when it dries it is BRILLIANT WHITE.
Lime kind of burns your skin, so don't get it on your skin or eyes. I did all the mixing right on the roof so I wouldn't have to lug all that water up the ladder. Just kept the water hose running while  worked. Painting was easier by just dumping a gallon or so at a time right on the roof and just rolling it evenly. It took about 6 hours of work to accomplish the task.

Here are the results of this experiment: Attic temperatures were reduced by about 30 to 40 degrees.... and house temperatures were reduced about 8 or 10 degrees. Some folks might think 8 or 10 degrees isn't much... but, it is right on the edge where we don't even need to run the air conditioner! I personally would not use AC at all.... but the wife still likes it ON occasionally.

If a simple home-owner like me can accomplish reducing my attic temperature by 40 degrees by using fourteen dollars worth of paint... why cant these roofing companies come up with something that can reflect the heat without breaking my bank account?

It has rained a couple times since painting... and the lime seems to be holding on OK and not rinsing off. Don't paint if its going to rain in the next 24 hours though. ONE neighbor asked what i was doing. I explained I was "coating my roof with special reflective coating" to reduce air conditioning costs. If he had objected, I would have mentioned that president Obama recommended doing this in one of his speeches!  Right now, this looks "unusual"... but in a few years i believe white roofs will be very common to reduce greenhouse gases and electric bills. One village in Greece has ALL their roofs white.

Art, just a re(tired) Fil-Am:
It all sounds and looks practical, but who would want an all white roof that doesn't fit the scheme/theme of one's subdivision, unless one lives in Greece or on the Greek Isle of famous Santorini where everything is all white washed, except for a few blue dome roofs!
We're in the Philippines and anything is possible, if one wants it to be and where there are no restrictions!

Our sub division has red, blue, orange and brown roofs on the houses. We went for the whitest roof they did, which is a creamish colour.
Not sure what difference it makes, but one can only try.


I think the lighter colour roof is a great idea, maybe not white but a light gray or tan maybe even a light blue.

Did you notice the roof vents thats another good idea, you don't want to trap all that hot air in the attic space it needs away out.
My brother put in a solar attic fan he told me it works great in the summer to help cool the house.

no need to insulate the outer walls of most houses in the philippines because they are made of cement hollow blocks etc...:)


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