This really needs to be emphasised to all the newcomers to SF.
In Fremont/San Jose/Sunnyvale you probably will need AC, but most areas you're probably fine with a few fans running, which are more environmentally friendly.
But alas, the culture here is changing. The sales people in our office have this lazy habit of opening the windows and keeping the AC running.
If so, AC unit might be the most economical option.
A typical air conditioner is one example of a heat pump, a device that moves heat from one location to another. In this case you're pumping heat from inside your house to outside, warming the air around the house.
Your refrigerator is also a heat pump, moving heat from inside the fridge to the outside. This is one reason cats like to climb up on top of the refrigerator (besides the fact that they like to climb on everything) - it's warm up there.
Not saying give up air conditioning altogether, but consider hanging out in an air conditioned public space instead of switching on your own. Libraries, malls, coffee shops, universities, just to name a few.
Of course 100% efficiency isn't actually possible.
That's bull. I won't have absolutely any effect on the planet if I run my AC 24/7 for all my life. The scales are way too different. You are free to do what you want but please spare me the sanctimonious baloney.
BTW, how do you get to the sea - I bet it's in a car and not on the back of a unicorn? At least most people do. Same as they get to air-conditioned malls (whose AC would probably be consuming energy couple of orders of magnitude more than that home AC) and other places. As I said, it's your choice how to deal with it but please, less posturing.
Oh and btw I love AC and am totally wtfing about not having AC now that it's hot and all the fans being sold out wrf.
> The collective use of air conditioning does indeed contribute to climate change.
Not significantly more than any other use of the same energy.
I hate being at home during the day anyway, but it's also to try to save a little energy ;) Everyone turning ther A/C on is actually making the planet hotter.