Take it from someone who ran a freestanding air conditioner inside a nylon tent while building his house: Without insulation, you're heating and cooling the sheds of power company executives ...

That's why I constructed a 10- by 12-ft. shed with a loft some years ago. Although I intended to fill the bays with insulation, I never got around to it. As it turns out, it hasn't mattered much.

Wool insulation absorbs and releases moisture, preventing mold and significantly enhancing indoor air quality.