I'll assume you don't have or don't use AC?
The purpose is what defines the purchase, and remember this,,,NO matter what fan you use. Fans are designed to cool people, not rooms. Certainly if you have decent outside temps, then the cross ventilation a fan might provide can reduce or increase interior temps.
The attic fan should likely be used in any case, especially in the summer, when I'm sure even Chicago has its share of warm weather. The attic fan is designed to expell hot air, not strictly to draw outside air, IN.
Whole House fan??? Define that.
If Fans will be your sole source of cooling then you should probably use a variety in combination. The second level will be warmer than the first, so expelling that warmth in the summer is the object. On the first floor fans that cause cross ventilation, and the attic fan to draw heat, helping the insulation be more efficient.
I'd suggest ceiling fans as well.
Rev. Steven
Source(s):
25 plus years as a contractor