I was wondering what the heat loss could be in the ductwork with no insulation. I've considered insulating the main trunk because if runs through an unfinished unheated basement. We have our wood furnace tied into the ductwork, so it's the main heat source for the home. I wasn't sure if there would be a large difference with the ducts insulated. Also what are some of the types. I do know that I need to insulate the duct in the attic because its super cold and that part of the ductwork heats the upstairs. Just wasn't sure what percent of heat loss can occur w/o insulation.