Towards Net Zero Energy Performance of the Montpetit Hall Building

Abstract

This thesis develops a simulation-based optimization framework for the deep energy retrofit of Montpetit Hall, a multifunctional institutional facility at the University of Ottawa. Constructed in 1972, the building exhibits high energy intensity due to its mixed uses, aging envelopes and systems, and complex thermal interactions. In Ottawa's cold climate, the study aims to reduce energy consumption and improve economic performance through integrated modelling, calibration, and multi-objective optimization. A detailed building energy model was developed in DesignBuilder and EnergyPlus and optimized in MATLAB using the Non-Dominated Sorting Genetic Algorithm II (NSGA-II). The model incorporated detailed 3D geometry, 128 thermal zones, envelope characteristics, and HVAC systems. Input data included Ottawa-specific weather records, institutional occupancy profiles, and NECB-based schedules. Baseline simulations were validated against 2022 utility data, meeting ASHRAE Guideline 14 with less than 5% Normalized Mean Bias Error (NMBE) and less than 15% Coefficient of Variation of Root Mean Square Error (CVRMSE). The optimization process was carried out in two stages, addressing envelope retrofits and HVAC improvements. Stage 1 focused on envelope and window retrofits, identifying Pareto-optimal solutions to balance primary energy demand and NPV. Results indicated that upgrading semi-exposed floors, roofs, and south- and east-facing glazing reduced heating demand by up to 19.4%, leading to overall energy savings of nearly 13%. Double-glazed, argon-filled windows provided the most favourable trade-offs. Cost-oriented scenarios prioritized selective glazing upgrades, while maximum-savings cases involved full envelope replacements. Stage 2 evaluated HVAC retrofits on the most energy-efficient envelope configuration, testing Variable Air Volume (VAV), Demand-Controlled Ventilation (DCV), Economizers, and Heat Recovery (HR) systems. The combination of these HVAC systems showed the highest savings in energy and economical perspective by more than 50%. Moreover, renewable retrofit strategies, photovoltaic panels (PV), solar thermal collectors, photovoltaic-thermal panels (PVT), and green roofs were also analyzed, and a comprehensive feasibility assessment was undertaken to identify the scenarios that provide the most favourable economic returns. This research contributes to the literature by assessing the effectiveness of a two-stage retrofit optimization framework applied to a complex institutional building in a heating-dominated climate. By integrating simulation, calibration, and optimization, the study establishes a replicable methodology with direct implications for institutional decarbonization and sustainable retrofit strategies in mid-century Canadian buildings.