Having just moved into a house on the start of summer, my wife and I found it was unbearably hot on hot days, but really just in one room with a vaulted ceiling: the parts of the house covered by the regular, narrow attic were much cooler. I'd been looking into all house fans, but was concerned that they would not solve the problem in my house because they must be placed in the parts of the house without the heat problem and try to draw hot air down and around corners to reach its intake.
I found a device made by a Massachusetts company, Tamarack Technologies, which would directly vent to the outside of the house and close shut at R10 insulation level when not in use. This seemed like the way to go. After failed attempts to get one-trick-pony whole house fan companies to step outside their boxes, I just ordered the unit so that now I could just go on Thumbtack and say "install this unit". Separately I got a quote from the company who last serviced the roof on the building, but the estimator basically told me they weren't interested in the project.
Kasra at Sustainable Roofing Solutions was a breath of fresh air. Trained as an architect and an expert in passively efficient building designs, he listened and said I was spot on with my concerns about the air flow. He gave me good ideas about more common solutions to this problem - in particular suggesting a powered skylight. I very nearly returned the unit and went with his suggestion - until we discovered that the specific roof design of the house made a skylight less suitable. But once we had determined that was a dead end, I got enthusiastic, professional and capable work.
All in all, the project came in on time and budget. I'm very satisfied with the outcome, and it has definitely made my home livable on hot days and the evenings after.