Exclusion-list methodology for weatherization program in the Pacific Northwest

Abstract

The Bonneville Power Administration (BPA) weatherization program includes measures that have the effect of reducing the ventilation rate in the structures in question, thereby not only saving energy but also increasing the potential for increased concentrations of indoor-generated airborne pollutants. In order to avoid having a significant impact on the health of occupants, certain classes of homes were excluded on the basis of house characteristics that may serve as indicators of higher-than-average sources of indoor pollutants. The purpose of this document is to examine the list of excluded classes of homes and to delineate an approach for modifying that list in order to increase the number of houses for which infiltration-reducing measures are offered. The nature of the weatherization program, particularly with respect to infiltration reduction, what is known about the sources and concentrations of indoor pollutants, as well as their health effects are surveyed. Techniques for controlling levels of indoor pollutants, whether by source control or by ventilation and air cleaning, are reviewed. The main considerations relevant to changes in the exclusion list and for formulating the elements that ought to be available in conjunction with such alterations are identified. It is concluded that the two major exclusion classes, that for radon has the greatest potential for reformulation in the near future to permit offering of infiltration-reducing measures to a significantly larger number of homes than at present; a comparable basis for changing the wood-stove exclusion does not yet exist. It also appears feasible to offer infiltration-reducing measures, in some cases, even if an unvented combustion appliance or urea-formaldehyde (UF) foam insulation is present: for gas stoves, if provision of a ventilation hood is deemed adequate, and for UF foam insulation, if monitoring demonstrates low formaldehyde levels.