If you use a whole house fan, there is no point in having a sealed attic system. You need an old fashioned "open" attic system. You want the hot air to vent out through the gable ends. You have a grate in a hallway that opens and the (presumably) cooler air from outside the home is drawn in through the open windows through the home, through the grate, and exits through the attic vents. WHole house fans are NOT compatible with conjunctively using your AC system. And, as I mentioned, the exterior of the home must be cooler (and less humid) than the interior for the whole house fan to be a viable option. 85° is pretty hot for most people, and I presume you're in the South where the humidity is also very high. Southerners LOVE their AC for a reason and long ago abandoned their whole house fans except for about 15 days in the spring and fall. WHole house fans are like owning a convertable. It sounds like a good idea, and if you live in a place like San Francisco, it probably IS a good idea. But, for folks who live in most of the rest of the country, there just isn't enough ideal weather in the year to be able to fully utilize that top down motoring.

Have you considered an HRV [heat recovery ventilation] unit that constantly brings in fresh air?

Quite a lot more expensive, but a superior system overall.

Well I am in the mountains of North Carolina and most people really don't use AC a lot. I just want an alternative to setting up box fans in the windows to keep the air flowing and a good breeze blowing. It's not necessarily the fresh air I want. It's the breeze.

And by the way, our main car is a convertible! When we lived in Charlotte it actually was too hot for the convertible most of the summer, but now that we live in the mountains we have tripled our convertible season. Days are sunny 60s and 70s three fourths of the year.

So what I hear you saying is that I can't seal my attic if I use a ventilator which is what I suspected. Will I still be able to get Energy Star and Healthy Built?

We live in Georgia and just installed one in the home we are building. We had one in our last home and absolutly loved it. I'm with you on loving the noise and breeze they give you in the spring and fall. We bought ours for $200 and they sell a cover on ebay for the $25 to seal up during the winter.

Any recommendations on brands/models of WHFs? I need to buy two to cover two wings of my 7,000 sq ft house so they probably need a capacity to cover about 2,200 sq ft each with 11' ceilings.

I live in the Sacramento area, >20% humidity, highs in the 90's and lows in the mid-50's during the summer. I'm told it's ideal for WHFs.

We are building at 4500' in the sierra nevadas. Summer days can get in the ninties, but the nights get chilly. You simply open up the house at night and first thing in the morning shut the house up tight. No mechanicals, no a/c needed. The house stays cool all day through the evening where you simply open up the windows again!

sierraeast, we already open up at night and close up in the morning and that works fairly well...depending on how cool it is at night, how long it stays that way, whether there's a breeze, how frequently you're going in/out of the house, etc. And despite 2x6 exterior walls with insulation and high-E double pane windows, it can get into the mid-80's inside the house by the early evening.

A WHF will cool down the attic and allow our clay tile roof to act as a heat sink. And it will facilitate cooling rooms with only one small window and no cross-ventilation.