Why is it important to insulate ducting that is outside of the envelope?

Insulating ducting that is located outside of the thermal envelope of a building is essential for preventing thermal transfer. When ductwork is uninsulated and exposed to outside temperatures, the air within those ducts can lose heat in the winter or gain heat in the summer, significantly affecting the efficiency of a building's heating and cooling systems. This thermal transfer can lead to increased energy consumption as HVAC systems work harder to maintain desired indoor temperatures. By insulating the exterior ducting, energy losses can be minimized, resulting in better overall energy efficiency and comfort within the living spaces.

In contrast, while reducing noise pollution, improving air quality, and enhancing structural integrity may be benefits of certain building practices and materials, they are not the primary reasons for insulating ducting that lies outside the thermal envelope. The main focus of insulation in this context should be to address energy efficiency and thermal performance.