Moving Ducts Inside: Big Builders, Scientists Find Common Ground

Panel: Residential Buildings: Technologies, Design, Performance Analysis, and Building Industry Trends

Authors:
Michael Lubliner, Washington State University
Ryan Kerr, Consol
Andrew Gordon, WSU Energy Program
Chuck Murray, Washington State Department of Trade and Economic Development

Abstract

Many national building science experts recommend the best way to increase HVAC system efficiency is by moving the air handler and ductwork from unconditioned space to inside the home (ASHRAE 2004). Techniques for moving the HVAC system within the conditioned space are well known, and the costs for making this transition are generally less significant than other residential energy conservation measures. However, in practice this approach is rarely used by production builders.

In working with production builders in the Pacific Northwest, the WSU's Building America research team has found it possible to move the HVAC system inside (within the thermal and pressure boundary of the home), with minimal cost increases, inconsequential loss of indoor space, and significant energy savings.

Using field test data as inputs, energy simulation software models were used to evaluate energy use in four high performance Energy Star test homes. Moving the HVAC system inside offered the highest incremental energy savings compared to all other above code energy features. Computer simulations predicted annual savings of about $100 in Portland, OR, and $200 in Spokane, WA (Lubliner et al. 2007).

This paper will focus on making the case that this technique saves energy, is practical for production builders (when accompanied by careful pre-planning), and creates significant and marketable energy savings for homebuyers. The paper will discuss design charrettes with production builders, best practices from building scientists and builders, and provide examples of how other builders can apply this approach.