Analyses the effects of duct insulation levels on residential HVAC energy use by means of an integrated residential building simulation system. The results from the simulations, along with cost estimates for HVAC systems and energy, are used as inputs for life-cycle cost (LCC) estimates. The estimates of cost savings, both initial and operating, include resizing the system to maintain its effective capacity, i.e., the conditioning energy supplied to the space, as the duct system is improved. Despite the small conductive losses (9% of HVAC energy consumption at most) in the prototypical houses simulated, which resulted in small energy savings (on the order of 3%), it was found that duct insulation levels that are higher than those used in current practice will result in lower life-cycle costs for all but mild climates. Resizing HVAC systems was found to increase energy savings by at least 10%, except in the case of heat pumps, which utilised significant supplement resistance heating for which savings actually decreased with resizing.

KEYWORDS: year 1996, domestic, ducts, thermal insulation, energy consumption, energy conservation, service life, costs, economics, calculating, conduction loss, heating, ventilation, air conditioning, building services, heat pumps