I'd love to hear what ideas you have for hot climates - last summer it got up to almost 50c (120f), but thankfully since it's the desert evap works wonders.  I'm not aware of anything that is efficient at converting heat into cold short of something like an ammonia loop, but I tend to limit my DIY adventures to things that don't use lethal gas if you screw up.    The biggest issue that I'm aware of with something like that is that the heat-density of mining gear isn't high enough to make it cost effective - but of course if you were running a chiller loop or something similar, then it would be an option.