Building Nx is an ambitious deep energy retrofit located at Humber College’s North Campus. The renovated 1980’s building has achieved Passivhaus EnerPHit Certification and Zero Carbon Building Standard – Design, in addition to receiving the 2020 Canada Green Building Council (CaGBC) Green Building Excellence Award as an Existing Building. B+H was tasked with implementing a complete replacement of the building envelope and the existing mechanical and electrical systems. Over its lifetime of use, Building Nx shifted from its intended use as a campus library to faculty office spaces. Following this use change, longer-term occupants quickly learned the building was drafty, and workstations suffered solar glare and uneven lighting due to the extensive use of glass block and poorly performing sandwich panels. To improve this, the new windows were located to prioritize views and head and sill heights were optimized for usage. The overall window-to-wall ratio was reduced significantly. The reduction of glass and optimized placements, combined with high-performance triple-glazing and exceptional building envelope thermal performance and air tightness, addressed glare issues, improved access to daylight, and provides exceptional thermal occupant comfort.
Two key strategies were implemented to reduce energy and GHG emissions. First, the building enclosure maximizes passive design strategies and significantly reduces the amount of active heating and cooling required from the building systems. Second, the HVAC system is based on a dedicated outdoor air system (DOAS) with localized heating and cooling and heat pumps for space conditioning. Additionally, the PV rooftop array provides an onsite renewable resource which assists in offsetting the already extremely low energy usage of the building. Overall, a 70% reduction in energy use intensity, a 90% reduction in GHG emissions, and a 97% reduction in heating energy is achieved compared to the existing building. Building Nx is now the most efficient building on campus, performing 80% better than the average building.
The work on Building Nx also serves as an example to the building industry on how to perform deep, zero carbon, energy efficiency retrofits on existing buildings in the Southern Ontario climate. Building Nx achieved Passivhaus Certification and the Zero Carbon Building Standard – Design Certification, all while remaining fully occupied. Temporary hoarding was put in place to maintain occupancy while the building envelope was being replaced. Once installed, the building’s highly insulated and well-sealed envelope was able to maintain comfortable internal temperatures for several days without active heating to permit the mechanical upgrades to take place during the coldest winter days. Due to the extensive nature of the building envelope replacement and its proven testing performance results, the project surpassed the target EnerPHit certification to meet the more stringent PassiveHaus certification, standing toe-to-toe with new builds. Building Nx demonstrates to long-term building owners, such as colleges and universities, that it is possible to improve their existing building stock and become pillars in the building industry for sustainability and forward-thinking projects. It stands as a shining example of what can be achieved in sustainable retrofit design with creativity, collaboration, and dedication.