My home had one prior owner before I bought it. Apparently, the husband was sent to the garage on many occasions because he had cut a window on the only area with wood siding in which he placed a $100 window AC unit. He did a very professional job. He also installed a ceiling fan. As I am the woman of the house, I make the rules so I get all the inside space and my boyfriend gets the garage.
He says it is very comfortable in the summer time and is warm enough in the winter time with one of those safe radiator type heaters. I haven't seen much of an impact on the electric bill either. Now the noise level cannot be solved by either one of these solutions.