Unfortunately, air conditioning in the Seattle area is rare. It is just
not
cost effective for the handful of days that traditionally get this warm. I
have the windows open and the fans running. It will get down to the mid
50s
to low 60s during the evening, so this is only a problem during the mid to
late afternoon. During the rest of the year, temperatures are not a
problem.
You could probably go to Wally World and get a 5000 BTU window unit for
around $100. That would make a significant impact on a single room, and just
pack it up in the garage when it gets cool enough to not need it. Even if
you ran it for 10 hours a day, you're still talking less than $0.50/day in
energy costs.
P.S. I don't even set my thermostat to 70 in the winter. 68 is plenty warm
enough :)
Oh, 70F is my summertime setting. I set it to around 65 in the winter. I
like it cold. :)
Greg