Sizing HVAC equipment is very important from the standpoints of both comfort and energy use. Heating and cooling equipment that are over-capacity will not run as frequently or as long when it does run. In both cases, this may mean poor humidity control. It could also result in temperature variations or noticeable cycling. Over-capacity equipment will not be as energy efficient as properly matched capacity either. On the other hand, equipment that is under-sized, will obviously result in loss of comfort during temperature extremes.