I could not agree more: People don't wear insulation (e.g., sweaters) in winter, the heat escapes from their body, and then they heat the entire house/office in order to warm themselves up again. You already have the heat! It's getting away!

Summer has similar situations. Point a small fan at yourself and you can save a lot on cooling the entire unit. A fan is blowing a gentle breeze across my hands right now (tip: aim it across the keyboard; it cools the laptop and you, and it doesn't dehydrate me). As long as the ambient temperature is below about 85, I'm fine. Think of it: 80 degrees, in the shade, with a breeze. That's pretty nice.