tu7001's comment shouldn't be down voted, it is correct. The human body has to expend energy to heat or cool itself when the ambient environment is outside a certain narrow range. Sweating burns some calories, even if you're just sitting around. When we spend our time inside climate controlled rooms then we burn fewer calories. The effect is small, but measurable.

https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3975627/