Energy Performance, Comfort, and Lessons Learned from an Institutional Building Designed for Net Zero Energy.

This paper examines the early performance of the Varennes Library, a building designed for net-zero annual energy balance in Varennes, near Montréal, Canada. It produces electricity from a 110.5 kWp building-integrated photovoltaic (BIPV) system where heat is also recovered from a section of the array and used to preheat the outdoor air intake. The building's many architecturalandmechanicalfeatureswereintegrallydesignedtoachieve the net zero energy target over a five-year averaging period with several key decisions made at the early design stage. These include the shape, area, andorientation of the roof thatmaximizes electricity productionfromtheBIPV(partBIPV/T[building-integrated photovoltaic/thermal with heat recovery]) system and a design layout that promotes daylight penetration and natural ventilation/freecoolingduringthecoolingseason. In the firstyear after inauguration, an operational energy use intensity (EUI) of 24.8 kBtu/ft²y (78.1 kWh/m²y) was achieved and has since been reduced to 22.20 kBtu/ft²y (70.0 kWh/m²y). Considering renewables production, the net-energy use intensity (EUI) is 4.60 kBtu/ft²y (14.5 kWh/m²y). This is a 95% EUI reduction over the national institutional average and can be further reduced with additional (ongoing) commissioning efforts. Suggested improvements in operation include ensuring the electricity production is optimized and any faults corrected, dimming electric lighting when daylight is sufficient, extending the hours of natural ventilation, and better utilization of the hydronic radiant slab for thermal storage using predictive controls. This paper discusses the process followed in the design of the library, its key features, its early performance, and some of the lessons learned. [ABSTRACT FROM AUTHOR]