Keeping a multi-story house cool using AC and attic fan?

[Martinjmpr]

Thanks to some suggestions here were had a very nice 3.5 ton central AC unit installed back in March. After our brutal Summer last year I felt we had to do something.

Now I'm looking for tips/tricks/suggestions on the best way to use what we have.

Here's our situation: We have a 40 year old house that was not originally built for AC. It is reasonably well insulated for a house that was built in 1979. It's located in the Columbine area, near Columbine HS so those of you who are familiar with the area can probably figure out what general type of house it is.

The house is a tri-level with a finished basement (so basically it has 4 levels.) The basement is finished as an extra bedroom but we mostly use it for storage.

Other than the basement, the lowest level is the "garage level" which includes the family room, where we spend most of our time when we are not in bed. Next level up (about 5 steps) is the kitchen/dining/living room, and then nearly a full level up (let's say 15 steps) is the "bedroom level" with 3 bedrooms including the master and 2 baths. My office is one of the upstairs bedrooms.

Our house faces to the South but doesn't have a lot of windows on the South side except upstairs. The garage faces South and the garage door and garage walls are fully insulated.

The new AC unit does a wonderful job of keeping the two "main" levels cool, i.e. the family room and the kitchen/living/dining room.

It does less good at keeping the upstairs cool, and the issue there is that 2 days a week, I work from my my office upstairs.

The house originally had an attic fan, which it sill has.

What we have been doing lately (still experimenting) is this: At night, AC is OFF and windows are open. If it's cooler outside than inside, we run the house fan to pull cool air outside and into the upstairs. Usually it is reasonably cool in our bedroom by the time we go to bed at 10:30 or so. We have a small floor fan in the bedroom which runs all night to keep air circulating. Windows are open in the bedroom, my office, and downstairs to let cool air in.

We shut off the house fan at night because the wife doesn't like the noise (personally I'd like for it to run all night, I don't mind the "white noise" but, "happy wife, happy life", right?)

In the morning, windows stay open (especially the windows downstairs) and we leave the AC OFF and turn on the house fan, again to pull in cool air.

About 10:00 or so, when it starts getting really warm outside, house fan is turned off, all windows get closed and AC is turned on. In addition, if I'm working in my office (which is on the West side of the upstairs), I shut the blinds and the curtains.

We generally leave the windows closed and the AC on until it starts to cool off outside - say, 7:00 or even 8:00 if it's a really hot day. Once it's cooler outside than inside, we shut off the AC, open the windows and turn on the house fan.

So does this sound like a good plan? We have only just started and as I said, we are still kind of experimenting. Just looking to see if there are any tips or tricks anyone else can suggest.

Right now the biggest issue for me is that it still gets very hot in my office in the late afternoon when I'm working. Wife is usually downstairs so she doesn't have any issues with the upstairs heat.