painting to cool house
 

Does painting the outside walls of a house white help much to keep it
cool? Do people living in the desert tend to have light houses?

thanks
Laura

"Lacustral" wrote in message
...
Does painting the outside walls of a house white help much to keep it
cool? Do people living in the desert tend to have light houses?

thanks
Laura

Dark colors do absorb heat more than light. Good insulations is also
important.

If you are in the desert area yes. at 30f something black can be 40 f
warmer than something white measured with an IR thermometer. Do your own
test by an Infra.Red. thermometer at Radio Shack

Lacustral wrote:

Does painting the outside walls of a house white help much to keep it cool?

On a 90 F day, 1 ft^2 of R20 light-colored wall outside 80 F air would gain
(90-80)1ft^2/R20 = 0.5 Btu/h. A dark wall in full sun might have 250 Btu/h
= 0.1741x10^-8((T+460)^4-(90+460)^4), so T = 236 F, and (236-80)/1ft^2/R20
= 7.8 Btu/h, eg (7.8-0.5)8x40 = 2340 Btu/h more for an 8'x40' wall.

Do people living in the desert tend to have light houses?

They should, but some "planned communities" in Arizona specify _maximum_
reflectivities for walls and roofs, based on aesthetics... :-)

Nick

Lacustral wrote:
Does painting the outside walls of a house white help much to keep it

cool? Do people living in the desert tend to have light houses?

thanks
Laura

Andy writes:

Generally speaking, yes. The more "heat" you can reflect from
the surface of the house, the less is absorbed into the structure
which heats the inside.
A reflective metal roof will do wonders, also.

But bear in mind that the opposite occurs in the winter, when
it would be nice to absorb all the heat from the sun and the
surrounding that you can. I understand that the desert gets
really cold in winter, and you generally have to use more
energy to heat up something than to cool it off a few degrees, since
there is a mechanical advantage in BTUs of cooling, but you
usually have to burn something to heat.......

So, whether or not a really reflective dwelling is a good idea
depends pretty much on where you are located and the summer/winter
sunshine characteristics..

If you were to "re-paint" and "re-roof" twice a year, it might
work pretty good, but I haven't heard of anyone actually using
this fantastic idea of mine.... :)))))

If you shade your house with trees, you can accomplish the same
thing, and the neighbors won't mind...... Oops, I mean shade your
house with cactusseses.... :))))

Andy

Lacustral wrote:
Does painting the outside walls of a house white help much to keep it
cool? Do people living in the desert tend to have light houses?

thanks
Laura

Yes and yes, but don't expect too much.

There is a larger effect for those living in a desert type area, and
remember if you live in an area that requires heating a good part of the
year, the reverse is also true.

I would look especially to the roof color. While a properly vented roof
will reduce the direct heat gain to the house a light roof will help keep
the roof itself cooler and help it last longer.


--
Joseph Meehan

Dia duit

"Lacustral" wrote in message
...
Does painting the outside walls of a house white help much to keep it
cool? Do people living in the desert tend to have light houses?

Beyond the other responses, the website for the county that I live in
recommends shading your outdoor A/C compressor with a tree.

But bear in mind that the opposite occurs in the winter, when
it would be nice to absorb all the heat from the sun and the
surrounding that you can. I understand that the desert gets
really cold in winter, and you generally have to use more
energy to heat up something than to cool it off a few degrees, since
there is a mechanical advantage in BTUs of cooling, but you
usually have to burn something to heat.......

Since he would only need to heat the house at night, it really wouldn't
matter what the color of his house is, however.

On 2 May 2005 09:07:42 GMT, (Lacustral)
wrote:

Does painting the outside walls of a house white help much to keep it
cool? Do people living in the desert tend to have light houses?

thanks
Laura


White and pastel colors tend to reflect the heat and keep the interior
cooler. How much depends on many factors, although there is little
difference. A shade tree will have a much greater impact.

Andy wrote:

If you were to "re-paint" and "re-roof" twice a year, it might
work pretty good, but I haven't heard of anyone actually using
this fantastic idea of mine.... :)))))

Maybe plants that lose their leaves in wintertime, eg grapes on a trellis,
over a dark wall...

Nick

wrote in message

Maybe plants that lose their leaves in wintertime, eg grapes on a trellis,
over a dark wall...

Nick

Often done in some parts of the country. Of course in the desert they can't
grow a big oak tree. East and South sides of the house have trees that will
lose leaves in the winter but give shade in the summer. Evergreens are
planted on the other sides to block the prevailing winds.

Edwin Pawlowski wrote in message
news:HYsde.7742$yd1.384@trndny01...

wrote in message

Maybe plants that lose their leaves in wintertime, eg grapes on a
trellis,
over a dark wall...

Nick

Often done in some parts of the country. Of course in the desert
they can't
grow a big oak tree.

Live Oaks and Mexican Blue Oaks do well where I am in El Paso, Texas.
Where they are legal, the classic shade tree in the desert is the
Mulberry.

Matthew

Matthew wrote:

Live Oaks and Mexican Blue Oaks do well where I am in El Paso, Texas.
Where they are legal, the classic shade tree in the desert is the
Mulberry.

Is this the tree that grows about 30-40 ft tall and has a redish-purple
fruit (http://en.wikipedia.org/wiki/Mulberry)?

Why would a Mulberry tree be illegal?

Jeff

"Jeff Cooper" wrote in message
...
Matthew wrote:

Live Oaks and Mexican Blue Oaks do well where I am in El Paso, Texas.
Where they are legal, the classic shade tree in the desert is the
Mulberry.

Is this the tree that grows about 30-40 ft tall and has a redish-purple
fruit (http://en.wikipedia.org/wiki/Mulberry)?

Why would a Mulberry tree be illegal?

Jeff

they are illegal, along with olive trees, here in the phoenix area. they are
incredibly prolific pollen producers, causing widespread allergy problems.

regards,
charlie
cave creek, az

Jeff Cooper wrote in message
...
Matthew wrote:

Live Oaks and Mexican Blue Oaks do well where I am in El Paso,
Texas.
Where they are legal, the classic shade tree in the desert is the
Mulberry.

Is this the tree that grows about 30-40 ft tall and has a
redish-purple
fruit (http://en.wikipedia.org/wiki/Mulberry)?

Why would a Mulberry tree be illegal?

The size is about right but the ones widely cultivated in my area are
a fruitless variety with a little darker leaves. New plantings are
illegal in my city and many others in the Southwest (USA) because they
cause an allergic reaction in many people.

Matthew

I suggest you want an overhang on the south side of your house with
windows.

In the summer, when the sun is high in the sky, the overhang will shade
the windows. In the winter, the sun is lower in the sky and the sun
can shine through the windows.

You want to shade the east and west sides in the summer.

find out about evap coolers and window shade screens

Mark

Thanks for the answers! I didn't mean to imply I live in the desert, I'm
in NY State. It gets hot and muggy here in the summer. I don't think
that the sun in the winter does much to heat up the house because
the sunshine is so weak & mostly cloudy days. My house is pretty dark on the
outside - roof and exterior walls are dark - I've been wondering how much
the dark walls contribute to baking me in the summer :) Steaming,
more like.

Laura