WhiteTea77581 wrote:
On Jun 17, 2:35 pm, Woody wrote:
Andrew Barss wrote:
I'm looking for advice and ideas for improving energy efficiency in my house,
especially heat from the roof and attic.
I own an older house in Tucson, and we are trying to do what we can to
decrease our electricity (mostly air conditioning) bills. The house has
a peaked roof, with a low attic that has minimal access. The attic has some
blown-in loose insulation between the ceiling joists, and nothing on the
underside of the roof itself (and putting anything there is essentially
impossible). We have some degree of venting -- there are small
vents on the two end walls near the peak, and two passive vents (rotary
type) on the roof, about four feet down from the peak.
I've heard various things, some conflicting, about how to better
the situation:
a) blow in a lot more insulation.
b) increase airflow using soffet vents (aka birdboard).
c) do both
d) do both, but with some sort of a channel up from the soffet
vents to above the insulation.
e) tear the roof off, put a lot of money into a high-tech roof
treatment. The curent roof is light-colored shingles,
and in quite good condition.
Anyone living in the Southwest have advice on what the best move is?
Thanks,
Andy Barss
I'd go one better than just adding active fans at either end of the
attic. I'd also add a whole house fan, mounted in the floor of the attic
(ceiling of the living area) to pull cooler air up from the house into
the attic. This air will be cooler than the outside air and will create
a cool airflow throughout the house.

Here's a fact sheet from consumer reports:http://blogs.consumerreports.org/fil...use-fans-1.pdf

~Mark.

My parents had one of those in the 1950's before they had AC.

In hot, humid weather the who house fan basically blows the hot air
around.

I think the goal is to blow the hot air out of the attic so it doesn't
migrate into the house.

Andy

As hot air rises *and* the hottest air is in the attic, how do you
propose it "migrate" to lower parts of the house?

My understanding (and what I did via an attic roof fan) is to cool the
attic air so that living spaces adjacent to it are not next to as-hot
attic air and thus reduce the AC demand in those living areas.

If there's one or more active fans on the attic vents (as I indicated
and previous responder suggested) then the hot attic air would escape
(i.e. be blown out) as cooler air, pulled into the attic via a fan
entered. Thus lowering the attic air temperature. Thus lowering adjacent
living space heat. Thus lowering AC demand. Thus lowering AC costs.

Typically, these are thermostatically controlled so that once they reach
some "reasonable" temperature level, you don't continue to blow living
space air into them.

~Mark.