Attic fan? Whole house fan? Neither? Both?

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I second the good advice given by Ed, Paul and Heathcliff. For the WHF to be effective, you need periods where the outside air is around 70 or below and not excessively humid. In the Philly area, that limits their usefulness to night usage in mostly the Spring and early Fall. You could also use the WHF in summer if the AC has been off and it's 85 inside, 75 outside, to drop the temp, then turn on the AC, But if the humidity is too high, it's questionable if it's worth it. If you have enough days where it works out for you, then it can be worth it.
The attic fan is there to move air out of the attic so that it doesn't get excessively hot. Before going with a fan, I'd make sure you have maximum natural convection venting, ie ridge, soffit, gable etc. If you can't get sufficient cooling that way, then a fan may be worth it. However, either type of fan needs adequate attic ventilation to be able to move the air volume.
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on 7/23/2009 5:57 PM (ET) snipped-for-privacy@optonline.net wrote the following:

Another use for a whole house fan is to remove smoke or odors from the house. Burn something on the stove? Dog comes in after an encounter with a skunk? Refinish a floor?
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wrote:

There are a couple issues related to cooling your house.
(1) The house looks like it has a southern exposure, which means while those skylights in what I presume is the living room will be great for adding passive solar heat in the Winter, they are needlessly heating the house in the Summer, unless you have shades/blinds over them or the like.
(1a) Cover that arched window on the second floor! Sheesh - that's adding all kinds of heat to that room (MBR?).
(1b) Consider awnings or some other form of shielding for windows that receive prolonged Sun exposure. Blinds and shades are helpful, but they don't stop the sunlight (in other words, heat) BEFORE it gets inside the window.
(2) In our area of the country (I'm west and slightly south of you, in western MD) the optimal insulation level in attic space is R50. Being your house looks fairly new, I'm going to guess you have the paperwork to check it out, or can contact the contractor who built it. The reason R50 is helpful is not simply for holding heat in during cold months, but for keeping the 120 degree heat of the attic in Summer from penetrating to the upper floors of the interior.
(2a) Ventilate the living daylights out of the attic space in the Summer, which means making sure you have enough soffit vents as others have mentioned, and perhaps having a thermostatically-controlled vent fan installed at one of the gable vents. While older models of attic vent fans are noisy - I know from hearing them kick in at an investment house I own - apparently there are newer models that are whisper-quiet, as long as you don't mind paying a bit of a premium for them (the same as with kitchen stove exhaust fans).
(3) Find an energy auditor to come to your home and do an assessment to see where you can additionally save yourselves some coin on heating and cooling costs. The Dept of Energy has links, and if you like there is the Interfaith Coalition on Energy (www.interfaithenergy.com) right there in Philly that is an faith-based group, which gives you a slight modicum of reassurance that they're not in the business of energy auditing to sell you products.
As far as the which-fan? question, I'm finding it darned-near impossible to find a decently-constructed window-mounted fan that could vent and allow me to cool off a couple rooms (my office, church secretary, and library), so I would say you'll probably have better luck finding a whole-house fan that vents into the attic than you would finding a fan to mount in a window. Even though that means a higher cost to install, what with having to have gable vents put in and all...
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: inside the window.
: (2) In our area of the country (I'm west and slightly south of you, in : western MD) the optimal insulation level in attic space is R50. Being : your house looks fairly new, I'm going to guess you have the paperwork : to check it out, or can contact the contractor who built it. The : reason R50 is helpful is not simply for holding heat in during cold : months, but for keeping the 120 degree heat of the attic in Summer : from penetrating to the upper floors of the interior.
: (2a) Ventilate the living daylights out of the attic space in the : Summer, which means making sure you have enough soffit vents as others : have mentioned, and perhaps having a thermostatically-controlled vent : fan installed at one of the gable vents.
I'm in a similar situation as the OP, except for living in Tucson, AZ, where the big problem is the attics getting extremely hot (160+ degrees) and radiating heat down into the living space. (I've come to realize peaked roofs make utterly no sense in Arizona).
The consensus seems to be that getting the built-up air out is the key, with air coming in from as low as possible (i.e. the soffet area), exhausting it passively at or near the peak of the roof, and making sure to have enough square feet of area in the inflow and outflow.
But there's remarkably little information out there about products, especially
a) soffet vents, other than cheap 16" x 8/10/12" perforatd metal, and
b) ways of getting the inflow of air from the soffits up above the attic floor and insulation (in an existing house).
I've been to three home centers and two roofing supply specialists, all in Tucson, and no one has any range of alternatives for (a), and none has a clue about (b). I was particularly struck by the fact that the roofing supply guys really had no idea there was even a problem in getting a clear pathway from a soffet vent to the airspace up above the insulation. (In my house, the roof slopes down enough that the sofets are about 3-4 feet below the attic floor, and so 4-5 feet below the insulation up there).
If anyone has any sources, even mail order, I'd appreciate the tip. What I'm looking for for soffet vents is a continuous length of peformated metal, that looks fairly nice, that could span a 24" wide and 23 foor long area.
    -- Andy Barss
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On Wed, 29 Jul 2009 02:52:56 +0000 (UTC), Andrew Barss

If you look at the old Florida "cracker" houses before they had AC here you will see a steep pitched pyramid shaped roof with metal roofing (reflective) and a cupola at the top that acts as a natural exhaust fan. They also have a porch roof all the way around the house to keep the sun off the walls and out of the windows. They have lots of windows and the cupola pulls the air in from the shaded porch and out the roof. If you translate that to an air conditioned house you have an insulated ceiling above the conditioned space. The air intake for the attic is generous air intakes in the soffits above the porch.
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On Tue, 21 Jul 2009 04:35:15 -0700 (PDT), "Chris (SilverUnicorn)"

Listen to your friend. You might consider additional insulation.
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