What should be done if HVAC ducts run through unconditioned spaces in a house?

When HVAC ducts run through unconditioned spaces, insulating them is essential to prevent energy loss and ensure the efficiency of the heating and cooling systems in the house. Unconditioned spaces, such as attics or crawl spaces, can experience extreme temperature changes. If ducts are not insulated, the conditioned air that they carry can be affected by these temperature fluctuations, leading to heating or cooling loss. This not only makes the system work harder, leading to increased energy consumption and costs but can also result in temperature imbalances throughout the home.

By insulating the ducts, the temperature of the air within them remains more stable as it travels to and from the HVAC system. Insulation helps maintain the desired temperature of the air, improving system efficiency and comfort in the living spaces. Additionally, properly insulating ducts can prevent condensation that might lead to mold growth or damage.

Options that suggest leaving the ducts exposed, vacuuming them regularly, or painting them do not address the vital need for thermal efficiency or moisture management, making them inadequate choices for ducts in unconditioned spaces.