Improving the Energy Efficiency of Air Distribution Systems in New California Homes

Thermal distribution systems represent the most promising opportunities for cost-effective energy savings in residential new construction. This paper describes the results of an unusual but on-going collaboration between the building industry, the environmental community, the research community, and the regulators to develop cost-effective, implementable procedures for improved heating, ventilating and air conditioning (HVAC) duct system design, fabrication, and installation.

The procedures were developed and their incremental costs and benefits were estimated. There are immediate heating and cooling energy savings of 12% or more obtainable from duct sealing alone at an incremental cost of approximately $250 per home. This incremental cost can decrease to zero with experience and competition.

Current practice for sizing ducts and HVAC systems does not properly account for duct leakage and some other duct losses, making it difficult to properly size systems that have minimal leakage. Modifications to the Air Conditioning Contractors of America (ACCA) methods and procedures for design and sizing ducts and systems are suggested.

An implementation strategy was devised to provide a practical, self-supporting means for the residential new construction industry to adopt and utilize these procedures. It involves first creating market value for builders using energy efficient mortgages and home energy ratings, which will result in market differentiation between homes with improved HVAC installations, and those with current-style HVAC installations. Second, the strategy proposes to provide credit in Title 24 for improved HVAC systems, and lastly, once there is significant market penetration of improved HVAC systems, require them as part of the energy codes.