You may find that one 3000sf home costs $600/month in the summer to cool, and another may cost $300/month in the summer to cool. Different builders take different measures to keep energy costs down, so don’t be afraid to do your research!
If you consider that for each additional $5000 on your sales price, your monthly mortgage payment increases by roughly $25/month- consider that translating to your electric bill. If your electric bill is $300 vs. $600, that’s a difference relatively each month between buying a $300,000 house and a $360,000 house payment wise. When you think about it that way you can afford a little more home, if you do your research and seek out energy efficient homes!
Especially where I am, in Arizona, if a home has poor insulation, or a poorly functioning AC unit, that can cost you a significant amount on your electric bill in the summers. Of course, a good general rule of thumb also is that the newer the home, the higher the building standard, and the lower the utility bill- but that is NOT always the case.
Always make sure that utility costs are inquired about during the inspection period!