Insulation is a vital component of climate control in a home. Heat will naturally distribute evenly through the air, so if you have a warm room and cold air outside, that warm air will naturally diffuse out into the colder air. While insulation does not completely prevent this from happening, it provides a barrier that effectively slows the process down so your home stays warmer or cooler for a longer period of time. While duct tape is not an effective insulator by itself, it can be used to greatly improve the performance of your insulation.
Locate any breaches or cracks in your current insulation and seal them by applying duct tape down the seam or breach on both sides of the insulation whenever possible. Cracks in walls, pipes and insulating sheets result in a lot of the heat loss in a home.
Place added insulation into any gaps in an attic or crawlspace and then run duct tape across it to hold it in place.
Wrap duct tape around any loose pipes or ducts to help hold the two pieces of the joint more tightly together, which will help insulate it and retain temperature for a longer period of time.