When it's cold, it's easy to get comfortable. You put on a sweater, or a jacket. You wear mittens and a hat. You use extra blankets, or an electric blanket.
When it's hot, you can only take off so much clothing. Once you're naked, you're not going to get any cooler. So you start sweating, which doesn't really help much, so just just end up naked and sticky (and not in a good way). If you sit down, then the chair gets sticky. And God forbid if you should have a leather sofa!
This house has central gas heating, which is really cheap to operate. Last winter, which was unusually cold, my gas bill was less than $5 higher than mid-summer. But the only air conditioning is a small electric window unit in the kitchen, which has to cool the entire 1400-something square foot house. It doesn't really lower the air temperature so much as it lowers the humidity, though either is a welcome relief. Unfortunately, it also costs a small fortune to operate (electric rates in San Diego are in the 16 cents per kW range).
It doesn't help that the attached garage is uninsulated and unventilated. It's 10:30 at night, and the temp in there is still 80F. I still need to buy another remote thermometer to check out the attic temp. I know the insulation up there is pretty poor (blown fiberglass, probably rated about R-5), and the only ventilation are a couple of whirlybird turbines (do those even work?). My sister's idiot husband destroyed the screen door on the back porch, so I can't open the front and back doors for ventilation until I buy a replacement.
The bedrooms, living room, and kitchen have ceiling fans, and I've got a window fan in my bedroom hooked to a timer so it automatically starts pumping in cool air from outside at night. These help a lot, and my bedroom is actually reasonably pleasant at night, except for one annoying thing.
I like to sleep in the nude, but under covers. Even if it's just a sheet, I like to have something covering me at night. And while the room is just right to sleep on top of the sheets, it's too warm to sleep underneath. I could turn up the ceiling fan, but it seems like a terrible waste of money to cool the room with the fan then warm up under the sheets.
I can't wait until winter.