What is the minimum level of insulation required for a portion of supply duct greater than 3 inches in diameter on the exterior of a residential structure?

The correct answer is based on the energy efficiency requirements established in Florida’s building codes. For a portion of supply duct that is greater than 3 inches in diameter located on the exterior of a residential structure, R-10 insulation is the minimum level required to help prevent heat loss or gain. This level of insulation is designed to ensure the efficient performance of HVAC systems, especially in a climate like Florida's, where temperature fluctuations can impact energy efficiency.

Choosing R-10 insulation provides adequate thermal resistance to maintain comfortable indoor temperatures while also complying with energy code mandates aimed at reducing overall energy consumption in residential buildings. This code requirement helps to ensure that the ductwork operates effectively and efficiently and minimizes energy waste, which is critical for both environmental reasons and cost savings on energy bills.

In comparison, higher levels of insulation such as R15 or R20 can be used, but these are not the minimum mandated by the code, and using lower insulation such as R5 would not meet the necessary energy standards for residential supply ducts.