air-conditioning - is it very unfriendly to the environment?

[Saker]

We are converting our garage into a gym and are considering putting in an air-conditioning/heating system. I have a feeling that air-conditioning is not very green but I can't find anything much on the internet about it or about alternatives. I wondered if anyone else had any info?

Very bad for the environment yes
Isn't your garage likely to be fairly cold anyway?
Or do you live in a hot country?

It's bad for the environment in the sense that it takes power to run (as does heating, for that matter).

How about a fan? If you get a really big one they can be very effective.

Presumably you wouldn't use the air con all the time, just when using the gym, so maybe it wouldn't be too bad

Big fan is good
An open window even better

In our old house we had warm air (gas) heating which also you could switch over to cold air in the summer. I think it was fairly efficient and cost effective. In a small space though, I'm not sure which would work out most fuel/environmentally efficient (assuming only switching on when needed, obviously) - that, or normal air con/heating, or fan/fan heater.

you need to make volume/btu calculations and make sure you get the right one for the size of the room, any bigger is wasteful

Thanks everyone for the comments - it's hard to say how warm the garage will get - we would have some windows put into the roof and it faces west so it would get the sun quite strongly in the afternoon. It's just we don't want to go to all the trouble of actually converting a room to use for exercise and then finding it is too hot. At the moment in the summer I exercise in the sitting room with a fan on and the window at the front open and the french windows at the back open. In the converted garage we could have the velux windows open and a front window but there would be no other air sources.

The idea was to get a dual air-conditioning heating system which would also be nice because of not using up space with radiators.

I guess we could see how it goes and get a portable air-conditioner if it was too awful but I would be irritated if I found out they were even less environmentally friendly. The logical thing would be solar-powered air-conditioning - I wonder if such a thing exists?

Does anybody know of anywhere where I could find out how energy efficient different systems are?