Magic

The entrance hall to my building has some sort of magical property. It has no heating vents or air-conditioning, and yet somehow (probably by magic) it is always the temperature you want it to be. That is, when you've been out running and it's really hot outside, the hall is nice and cool. If it's chilly outside and you're smarting from the wind having cycled home from work, it's nice and toasty warm. Magic, I say.