Infiltration and ventilation are responsible for one-third to one-half of the space-conditioning load, but are often underappreciated by occupants because it is difficult to notice air losses. They cannot, however, be arbitrarily reduced below a level that supplies acceptable indoor air quality without providing mechanical ventilation or some other mechanism for doing so.
Therefore, RESAVE was designed to address two issues: (1) to reduce direct losses from infiltration while controlling key emission sources, and (2) to find the most energy-efficient methods available to supply the needed whole-house ventilation. The "Built Tight, Ventilate Right" strategy generally is accepted as the best approach for building high-quality homes, but it is not easy to implement without strong technical backup and appropriate standards to follow.
Indoor Air Quality
The RESAVE program estimated that the annual health impact of indoor air is $400 to $1,100 per person. For California, the annual health impact of chronic exposure to indoor air is $15 to $40 billion annually.
Good ventilation is a primary strategy to reduce that cost, but air cleaning and source control options may be more cost-effective or provide lower energy solutions. Particle filtration appears to be especially promising and deserving of further examination.
Complying with Title 24 ventilation requirements (such as the ASHRAE 62.2 standard) for the entire California housing stock is projected to increase residential site energy by 2,600 gigawatt‐hours (GWh) annually at current building envelope air leakage levels.
Tightening residential envelopes has the potential to decrease residential energy demand by as much as 25,000 GWh annually, and the vast majority of that reduction (72 percent) could be achieved by tightening to the International Energy Conservation Code residential tightness standard.
Combined Optimization and Commissioning
This research allows indoor air quality to be monetized; that is, to determine a monetary value of exposures to contaminates in terms of occupant health. By doing so, these costs can be combined with energy costs so that the total consumer operating costs of optimizing both energy use and indoor air quality can be identified. The RESAVE program developed the procedure to do so.
Specific Research Areas
As part of the general results above, the RESAVE program worked on several research areas that produced stand‐alone results, including: Air leakage, the Residential Integrated Ventilation Energy Controller (RIVEC), and the Ventilation Guide.