The Heights: Gesa Zellermann and Scott Kennedy, Cornerstone Architects

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Gesa Zellermann and Scott Kennedy from Cornerstone Architecture rapidly led a rapt audience through one of the most packed presentations ever on the lessons learned from their firm’s pioneering 85-suite mixed-use development, The Heights, in Vancouver, B.C. The Heights was completed in 2018, and it’s almost hard to remember now how radical it was then to work out the detailing for a Passive House multifamily building. When under development, this project was toured frequently by local architects and engineers who were trying to keep up with Cornerstone.

Just as Cornerstone Architecture generally, and Scott Kennedy in particular, was generous about sharing information during The Heights’ construction, the Cornerstone duo was generous last Wednesday about sharing what was done right and what could have been improved. The building’s overall energy performance—fairly flat on an annual basis with barely a winter peak—demonstrates that in many respects the building is a Passive House success. Heating demand is almost exactly as predicted by the PHPP. Internal heat gains are higher than modeled, due to the building’s density and the typically high North American plug loads compared to European ones—a not surprising finding now, but that wasn’t common enough knowledge at the time. The electrical energy use of the common areas adds up to 30% of the building’s total use, which was also unexpected.

The biggest issue the building has is that it overheats in summer, and many factors contribute to this problem. The solar heat gain coefficients (SHGC) of the windows were selected for minimizing the heat demand in winter without fully absorbing the impact those windows would have on summertime conditions. Shading, especially on the south-facing façade, is less than ideal. Those higher-than-expected internal heat gains don’t help either. And, the climate data associated with the PHPP was based on actual historic trends, not on today’s quickly changing temperatures. The PHI has since developed a summer comfort tool for the PHPP to test a building’s comfort during projected summer conditions.

Get the whole scoop on what worked and what has changed in Cornerstone Architecture’s multifamily details by listening in to the Happy Hour video.