Conduction is the transfer of thermal energy through a material without the movement of the material itself, occurring through direct contact between molecules. In HVAC systems, conduction happens through ductwork, pipe walls, insulation, and building materials, significantly affecting heating and cooling efficiency.
Conduction Mechanisms and Rates
Heat transfer rate by conduction follows Fourier’s Law: Q = k × A × ΔT / d, where k is thermal conductivity (measured in BTU·in/hr·ft²·°F), A is area, ΔT is temperature difference, and d is material thickness. Copper has high conductivity at 2,700 BTU·in/hr·ft²·°F, while fiberglass insulation measures 0.27, demonstrating why proper duct insulation reduces energy losses by 20 to 30 percent.
HVAC Applications
Unwanted conduction losses occur through uninsulated supply ducts in unconditioned spaces, reducing heating and cooling efficiency. Strategic insulation installation in attics, basements, and crawlspaces minimizes these losses. Pipe insulation prevents condensation on refrigerant lines and reduces heat transfer to conditioned air.