Research Reports

This report is an extension of a previous analysis study titled “High R Walls for the Pacific Northwest – A Hygrothermal Analysis of Various Exterior Wall Systems”, conducted by BSC for Walsh Construction, dated June 1, 2010 that examined the predicted thermal and hygrothermal performance of 17 different wall assemblies in Portland, Oregon.

This report summarizes hygrothermal analysis of specific attics constructed in California. The analysis was done using historical experience, published work in journals and trade publications, current building code requirements and WUFI hygrothermal simulations to assess benefits and risks associated with insulating the roof decks in both vented and unvented configurations. The majority of the configurations evaluated are well understood and have been addressed in previous published work or in the model building codes. However, the focus of this report is on modifying conventional, ventilated attics, constructed with impermeable roof shingles (with fiberglass batt insulation on the ceiling plane) by adding fiberglass batt (or netted fiberglass or netted cellulose or spray applied fiberglass) insulation to the underside of the roof deck (i.e. on the slope) while leaving the attic air space ventilated to outdoors.

This paper was first presented at the 2011 ASHRAE Annual Conference. A startup builder in the San Francisco Bay Area has a goal of producing factory built/modular houses with net zero energy performance. Their first prototype was a two-story, two bedroom, urban infill townhouse design. It has been in operation for roughly a year, and has been extensively measured and monitored, providing information about its net zero performance.

This report considers a number of promising wall systems that can meet the requirement for better thermal control. Unlike previous studies, this one considers performance in a more realistic matter, including some two- and three-dimensional heat flow and analysis of the relative risk of moisture damage.

A calibrated ventilation model was exercised over a range of parameters seen in new and existing housing in the United States. This report was first published in ASHRAE Transactions (17, Louisville 2009). American Society of Heating Refrigeration and Air-Conditioning Engineers, Atlanta, GA. Reprinted with permission.

This paper reports on field measurements collected from over a year of monitoring two types of wood-framed walls: one with an air gap membrane and another installed following standard practice. Each type of wall was faced either north or south in a test hut located in southwestern Ontario.

A single-story, single-family, 1350 sq. ft. house located in Las Vegas, NV was outfitted with two separate ventilation systems. The systems were independent of each other, and were operated at different times to evaluate the relative difference in air change rate and distribution of ventilation air induced by their operation.

Ventilation air change rate, local mean age-of-air, and interzonal ventilation air distribution were measured for two single-family homes and eight ventilation systems.