Why is Infra red seen as hot even though it has a lower energy than UV?

Answer 1

To expand Luca's answer, things that are hot tend to radiate most of their energy in the infrared range. When they get really hot they can radiate in the visible range (red hot, like on an electric stovetop) or even up into UV (white hot, i.e. all visible frequencies and then some). But most objects you're likely to come into contact with do not glow visibly from sheer heat (and you know better than to come into contact with the ones that DO visibly glow).

Answer 2

The perception of something as "hot" doesn't depend on the energy per photon but, rather, how much of the energy gets converted into heat. The frequencies of infrared happen to correspond to what gets absorbed by most things we're familiar with ( skin, food, etc ).