Insulating Ductwork — The Overlooked Energy DrainYour air conditioner may be cooling air efficiently, but if that air travels through uninsulated or leaking ducts on its way to your living spaces, a significant portion of that cooling is lost before it ever reaches you. Duct insulation is one of the most impactful — and most overlooked — aspects of whole-home cooling efficiency.Where Ducts Run Matters EnormouslyIn many homes, ductwork runs through attics, crawl spaces, and garages — unconditioned areas that can reach extreme temperatures in summer. When cool, conditioned air travels through ducts surrounded by 130°F attic air, heat transfers rapidly into the duct, raising the supply air temperature before it reaches the room. The AC has already done the work to cool that air, but much of the benefit is lost in transit.Two Problems: Leaks and Heat GainDucts suffer from two distinct issues. First, physical leaks — gaps at joints, poorly connected sections, and holes — allow conditioned air to escape into unconditioned spaces. The EPA estimates that 20–30% of the air moving through a typical duct system is lost this way. Second, even sealed ducts experience heat gain if they’re uninsulated or under-insulated.What Proper Duct Insulation Looks LikeDucts in unconditioned spaces should be wrapped with insulation to at least R-6, and ideally R-8. This is typically accomplished with fiberglass duct wrap or rigid foam board. Duct joints should first be sealed with mastic sealant (not standard duct tape, which fails over time) before insulation is applied.The Best Long-Term SolutionWhen possible, the ideal solution is to bring ductwork inside the conditioned envelope of the home — relocating attic ducts to the floor of the living space, or encapsulating the attic and treating it as conditioned space. This eliminates both the leakage and heat gain problems permanently.Signs Your Ducts May Be the ProblemRooms that never cool down despite the AC runningNoticeably warm air from supply ventsUnusually high energy bills relative to similar homesExcessive dust in living areas