PHASED Twin Towers EnerPHit
For more than 40 years, two concrete high-rise towers in North Vancouver owned by Affordable Housing have been providing high-quality affordable housing, but decades of use have led to the need for a serious overhaul. Just from a mechanical perspective, the boilers were original equipment, as were the ventilation units, most of which are failing. Affordable Housing hired Impact Engineering, then known as HiH Energy, to update and optimize the mechanical systems.
Both towers feature a mix of commercial and residential spaces. The south tower has a ground-floor commercial space and 15 residential stories with 122 units. The north tower’s commercial podium takes up 2 stories; its additional 10 stories contain 90 dwelling units. Most of the suites in this social-housing complex are single occupancy, and the population tends to be older.
When Ben Mills, principal and founder of Impact Engineering, heard that Affordable Housing was simultaneously exploring envelope measures, he got excited. If he could bring the teams together, they could work with each other and develop a more substantial and comprehensive building overhaul. “I pitched an EnerPHit feasibility study,” says Mills, whose proposal was ultimately accepted. “It was a deep lesson in truly collaborating, which turned an unambitious project into a great one.”
The feasibility study has turned into a full-fledged plan to proceed with a renovation that is targeting EnerPHit-level energy criteria for the residential portions of the buildings. Both buildings’ mechanical systems will be fully decarbonized, and the building envelopes will undergo major retrofits, bumping up the walls’ effective R-value substantially.
Mills says the project may not quite meet all the EnerPHit targets because of the challenges of renovating a mixed-use building. “In order to make the air-sealing target, we would have to add doors and air-sealing details in the commercial spaces that wouldn’t make practical sense,” Mills explains. “What we will achieve is a high-performing resilient envelope, a decarbonized building, and reduced operating costs.”
The projected cost for all of these achievements was shockingly reasonable, according to Mills. As part of the feasibility study, his firm collaborated with a cost consultant to estimate the cost of replacing like for like and then compared that to implementing the mechanical and electrical portion of the EnerPHit proposal. “The delta between like for like and Passive House was a 25% uptick, which was mind blowing,” says Mills. The EnerPHit building will be far superior in terms of durability, reduced liability, occupant comfort, and resilience. For the first time the mechanical system will be able to actively cool the suites—a safeguard against future potential heat waves. “Financially, this project makes a really strong case for fully decarbonized buildings,” Mills points out
