Why normal human body temperature is much higher than most comfortable “room” air temperature? Why not equal?
Your body burns fuel to get the energy it needs to function. Just like any other combustion process, this generates heat. Since metabolism happens constantly, your body constantly generates heat. In order to keep a constant temperature, your body has to balance heat production against heat loss. It turns out that this is easiest when the air temperature is less than your body temperature, since you will lose excess heat to the air. That’s why around 75F (25C) tends to be comfortable for most people. If the air temperature is the same as body temperature, you can only loose metablic heat through the evaporative cooling provided by sweating. This isn’t as effective a process, so temperatures near body temperature aren’t generally comfortable. In fact, if the temperature is enough hotter than body temperature, sweating is no longer sufficient to maintain your internal temperature. As a result, the heat quickly becomes fatal.
