9:00 am - 10:00 am | Room: Owens Corning Room | Session Chair: Bomani Khemet

Evaluating Building Air Tightness

Quantifying Enclosure Airtightness Performance In Restored Historic Institutional Building

The choice to either redesign or restore historic office buildings in many of Canada’s downtown cores is a complex decision making process involving several stakeholders. Furthermore, the very jurisdictions where these buildings are located tend to be early adopters to increasingly stringent environmental sustainability codes. Since air leakage can account for up to 36% percent of heating and cooling cost in large buildings, there has never been a more important time to quantify the actual enclosure performance of such buildings.  

A compact, recently constructed 10,000m2 institutional building composed both of a contemporary curtain wall addition, and a historic masonry enclosure was evaluated for building airtightness. A whole building airtightness test was undertaken on the 12,300m2 of total enclosure area revealing a normalized flow rate of 2.205 LPS/m² at 75 Pa.  Two guarded tests were performed to separate the total air leakage rate between the historic section from the contemporary addition were the normalized leakage rates were 3.633 LPS/m² and 1.206 LPS/m² at 75 Pa respectively. The facades enclosing the historic and contemporary buildings were guarded such that the effective airtightness of the slab, foundation walls, above grade walls, and roofs were evaluated for air tightness. During the restoration, the majority of the interior plaster was removed from the historic structure to reveal the aesthetic of the historic brick, however, it is now understood that this plaster acted as an air barrier system and the removal is potentially the cause of occupant discomfort around the interior perimeter of the building. To assess this impact, two additional guarded tests are being undertaken for two identical “eastern” and “western” classrooms on the historic section of the building. The classrooms share the same 3rd floor elevation, southern orientation, roof detail, and interior floor and partition wall details. However, the eastern classroom’s vertical enclosure has exposed masonry both from the interior and exterior while the west classroom has exposed masonry on the exterior and 20mm of plastered interior air barrier and finish.  The result and analysis from the series of guarded tests are expected to have wide ranging implication for the designers, owners and contractors planning repairs, partial and full restoration of large historic building

Bomani Khemet, University of Toronto

Bomani Khemet is an assistant professor of building science in the Faculty of Architecture. Bomani is a registered professional engineer in the province of Ontario and earned degrees in Mechanical Engineering, Building Science and Civil Engineering. Bomani has had several years of experience teaching both Building Science and HVAC courses to practicing architects, engineers, and post-secondary students.  Bomani is specifically interested in researching aspects of design related to ultra-low energy, affordable homes, and buildings. Professionally, Bomani has over a decade of engineering experience in the private sector as a designer, and manager on a variety of fascinating projects - including construction, transportation, and industrial design.