The Northwest Residential Infiltration Survey: A Field Study of Ventilation in New Homes in the Pacific Northwest
Authors: Parker GB , McSorley M , Harris J 
Published: March 2009

A study was conducted in the Pacific Northwest region (Oregon, Washington, Idaho, and western Montana) to measure ventilation characteristics in electrically heated single-family, detached residences during the 1987–1988 and 1988–1989 heating seasons. This study generated information that will be used to develop energy conservation programs for Northwest homes. This data will be used to evaluate the cost effectiveness of various conservation measures, to establish residential building codes, and to help regional power planners in making decisions about the management of the Northwest's electrical resources.

The study was carried out under a three-way partnership. With support from the region's state energy offices, two agencies sponsored and reviewed the study: the State of Idaho's Department of Water Resources (IDWR) and the Bonneville Power Administration (BPA). Battelle Pacific Northwest Laboratories (Battelle) conducted the study under contract with these agencies.

During the first heating season 140 homes were tested in the study. These homes were built since 1980 to current building codes and practices in the region. During the second heating season, approximately 50 homes were tested that were constructed since 1986 to the proposed Model Conservation Standards (MCS). These energy-efficient MCS homes are equipped with whole-house mechanical ventilation systems.

The homes studied in the 1987–1988 heating season were selected from a list of 292 eligible residences identified in a random telephone survey. This survey was conducted in the top 43 growth counties in the region, representing approximately 90% of the regional population. The homes studied in the 1988–1989 heating season study were selected from records of new home construction in the region under utility-run incentive programs.

In the study, field technicians measured ventilation and infiltration in each home using two common techniques. The first technique was based on fan pressurization (using a blower door). Five Pacific Northwest blower door firms conducted the field work using field-evaluated orifice-type doors.

The second technique used perfluorocarbon tracer (PFT) equipment that measures the air exchange rate in the home for a two- to four-week period. A minimum of two, and maximum of three, different types of tracers were used in each home to characterize zone-to-zone air flows. Both measurements were used in analysis and evaluation of housing ventilation.

Before the ventilation measurements were taken in each home, an occupant and structure survey was conducted to determine occupant and house construction characteristics, and to identify heating and ventilation systems and their usage. During the time of the PFT measurement, the occupants kept a daily log to record activities that might influence ventilation (for example, exhaust fan usage). In addition, representative weather data was recorded for the home during the time of the PFT measurement.

A total of 134 homes tested during the 1987/1988 heating season had valid PFT and blower door data. The mean regional season PFT air exchange rate was 0.40 ± 0.19 air changes per hour (ACH) and 0.45 ± 0.20 ACH calculated using the Lawrence Berkeley Laboratory (LBL) model and typical meterological year (TMY) heating season weather data. The mean effective leakage area was 806 ± 458 cm2 at 4 Pa.