Air tightness of new houses in the U.S.

Most dwellings in the United States are ventilated primarily through leaks in the building shell (i.e., infiltration) rather than by whole-house mechanical ventilation systems. Consequently, quantification of envelope air-tightness is critical to determining how much energy is being lost through infiltration and how much infiltration is contributing toward ventilation requirements. Envelope air tightness and air leakage can be determined from fan pressurization measurements with a Blower Door. Tens of thousands of unique fan pressurization measurements have been made of U.S. dwellings over the past decades. LBNL has collected the available data into its Residential Diagnostics Database database, which it is expanding on behalf of the U.S. Department of Energy. This report documents what is in the envelope air leakage section of the LBNL database with particular emphasis on new construction. The work reported here is an update of similar efforts carried out a decade ago, which used extant data largely focused on the housing stock rather than on new construction. The current effort emphasizes shell tightness measurements made on houses soon after they are built. These newer data come from over two dozen datasets, including over 22,000 measurements spread over a majority of the U.S. Roughly one-third of the measurements are for houses identified as energy-efficient through participation in a government or utility program. As a result, the characteristics reported here provide a quantitative estimate of the impact that energy efficiency programs have on envelope tightness in the US as well as on trends in construction.