I do not have air conditioning. I save a lot of money compared to some others. But there are a few uncomfortable days of the year. I typically go to the movie theater or another air conditioned place those days, and sleep with a couple fans pointing at me during the night.
Two options:
You can just air condition one room with a window air conditioner or with a (less-efficient, but also can be put away) portable air conditioner. You don’t have to air condition your entire residence. Just close the door to the air-conditioned room.
Depends a bit on where you are in the Bay Area, but the place mostly has pretty low humidity (especially the bits that get toasty). As long as your relative humidity is relatively low, you can get an evaporative cooler and keep windows open and air flowing, same way you were before. You can only cool so far with one, but it’ll do more than fans. Much more energy-efficient than an air conditioner (though the flip side is that you need open windows and flow of fresh air with them, so you’re constantly cooling air).
If you buy quite a new model air conditioning, the cost of running it will not be so huge as the efficiency on those things have gone up past couple of years
