In terms of energy efficiency, what is the ideal condition for duct systems located in unconditioned spaces?

The ideal condition for duct systems located in unconditioned spaces is for them to be fully insulated. Fully insulating the ducts is important because it helps to minimize energy loss as air travels through the ductwork. In unconditioned spaces, temperature fluctuations can significantly impact the efficiency of the heating and cooling system. When ducts are not insulated, they can lose heat in the winter and gain unwanted heat in the summer, resulting in a decreased overall efficiency of the HVAC system.

Insulating the ducts helps maintain the temperature of the air as it moves through the system, ensuring that the conditioned air remains at the desired temperature by the time it exits the registers into living spaces. This, in turn, reduces the workload on the heating and cooling equipment, leading to improved energy efficiency and potentially lower energy bills.

Additionally, fully insulated ducts can help reduce the risk of condensation, which can occur on uninsulated or poorly insulated ducts when warm, humid air comes into contact with cold surfaces. This condensation can lead to mold growth and other issues, further complicating humidity control in the building.

Overall, properly insulating ducts located in unconditioned spaces is a best practice in building performance and energy efficiency for multifamily housing.