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We live in the top two floors of an old brownstone in NYC. It gets CRAZY hot on our top floor, which is really the attic of the house, but where we have our three bedrooms and one bath. It's also poorly insulated. The front two rooms have dormer windows and the back bedroom and bathroom have only skylights. There is also one window on one side of the house (the wall on the other side is against neighboring building's wall).

We are very low on cash or I would install a mini-split system. Researching whole house fans, they seem like a great option for us, but I can't figure out how we could do this if we live in our attic. Also our stairwells from 2nd to 3rd and 3rd to 4th floors are pretty open.

The ground floor and 2nd floor of the building have separate studio apartments; we have our door on the 2nd floor landing, so the landing is also part of our living space.

I hope someone has an idea, I can't find anything about this on the web!

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    Do you own, or rent?
    – Ecnerwal
    Jun 8, 2017 at 17:14
  • Thanks to all for all these great answers! Unclear from my post -- There are four rooms on the fourth floor. Two have opening skylights. Then an open room with open stairwell and 2 windows -- these windows open but one has the a/c in it but could be opened from the top. One more bedroom w/one window in it. From what I have read here of these answers, it still seems like my only option is to create a miniature attic just for the whole house fan? This sounds really expensive! See my post below.
    – Gerda
    Jun 9, 2017 at 12:49
  • ...no, that's not your only option.
    – Ecnerwal
    Jun 9, 2017 at 14:51

4 Answers 4

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I love whole house fans , have now installed them in 4 houses and 2 garages. As noted they can only reduce temperature to the outside temperature. But that works well with a night temperature below 70F and a day temp above 80F , running an hour or so in the morning. Ideally you need to install it in a gable for your situation. You may want an insulating foam panel to put over the louvers when the fan is not on as louvers leak air. I recommend a belt drive as the direct drive turn the fan faster making significantly more noise. As noted , windows need to be opened to let air in,; window adjustment also lets you focus the cooling.

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  • I find better effect running all night, from whatever time the outside temperature drops below the inside temperature - it takes more than an hour to move the thermal mass of the house down near the outside temperature. Shut off in morning as outside rises to inside temperature.
    – Ecnerwal
    Jun 8, 2017 at 18:07
  • This is an add-on to my post above. Tin gable would need permit that I'm not sure I could get, because it could be seen from outside, historic NYC designation. I was wondering about creating a little version of this inside the house if I could figure out how to vent it from the roof. But maybe if I was able to stick it over the bathroom skylight, it wouldn't be noticeable and I could do it that way. But then I would lose the light/air to the bathroom?
    – Gerda
    Jun 9, 2017 at 12:49
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If the sky lights can be opened, then you could add window fans blowing into the rooms and allow that air to escape thru the sky lights. Where I live you can buy window fans that fit in windows just like screens,and the fans can be run blowing in or out. If the sky lights can not be opened your solutions are limited to a couple window A/C units and a couple floor fans to blow conditioned air into the rooms with no windows.

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You would be looking to place a fan (which might not be the typical large "whole house" fan, since you'll be limited by the window/skylight size) in one (or more - possibly all) of the 4th floor skylights or windows, blowing out, and open the 3rd floor windows for intake air. Or, put fans in the 3rd floor windows blowing in and open the 4th floor windows/skylights for exhaust.

If you own, and can safely access the roof, a short-term low-cost partial solution would be to whitewash the roof and reduce solar heat gain. Longer-term solutions would be to fix the insulation, possibly in a re-roof that adds significant insulation (4" or so of foam boards) to the top of the roof deck and finishes with a white or silver surface.

Not fixing the insulation will simply make the air conditioning you can't afford even more unaffordable to run, if you ever get to affording it.

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Where I live, we don't have/use "whole house fans", but I keep hearing about them. To me they don't make sense.

If the exhaust fans are installed in the attic, they'll just draw air in through the soffit vents, gable attic vents, etc. and not vent the house because the house will have more resistance to air infiltration than the attic vents.

Likewise, if the exhaust fan is installed in the house, then it would need relief grilles in the house (or just open the windows) to allow air into the house. This, of course, would not affect the attic at all.

Exhausting air out of the house means bringing in "make-up" air from the outside. So, the "best" temperature you could hope for is the ambient outdoor temperature. So, if it's hot outside and you want to exhaust hot indoor air, the best you could do is match the indoor temperature to the outdoor temperature. Right?

Hmmm...What am I missing?

(There is a type of "air conditioning " that brings in fresh subterranean cool air, but that requires underground air ducts...and that's not the principle of the whole house fan.)

I know that just having air blow across your skin (even warm air) will cool you off. So why not just sit in front of a fan?

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  • I have read a lot about whole house fans and I think you are missing something but I am not knowledgable enough to explain. However, at night, temp drops way below the temp in our bedrooms/attic. All day long all the heat of the whole house is rising into it and the sun is beating on the roof, so it could be 95 degrees in there and 75 degrees outside at night. My understanding is that the fan is something for night time. And I HATE a/c and our house is so leaky that it's very hard to get an effect from it anyway. So that's why we thought of this.
    – Gerda
    Jun 9, 2017 at 12:53

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