Coupling Phase Change Materials and Model Predictive Controls for Energy Efficiency and Thermal Comfort in Canadian Buildings

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Envelope thermal performance requirements are becoming more stringent and the most common compliance approach is to add more insulation. In many cases this may not be practical due to space constraints and greater use of glazing façade systems. An alternative approach is to increase building envelope's thermal storage capacity by incorporating Phase Change Materials. PCMs are innovative products able to store and release large quantities of heat per unit of mass through a phase change from liquid to solid and back near typical room temperatures. The idea is that PCM absorbs part of a building's heat load during the daytime as it melts and releases this heat during the cooler night-time by returning to its solid phase. In the summer, the released heat would be flushed out using natural ventilation or fans, while in the winter it would reduce the heating requirements. However, successful and cost effective application of PCMs in buildings depends on careful selection of many factors including: working temperature range, material thickness, location within the space, and location within the building component. Additionally, the PCM material should be able to completely discharge its absorbed energy during the night to be fully effective. This often requires changes in the operation of heating, ventilation and air-conditioning (HVAC) systems. Model predictive control (MPC) is a multivariable control algorithm that can be used to override conventional HVAC control strategies and provide optimal conditions for a complete phase transition of PCMs in 24-hr. MPC considers thermal response of building systems and future projected climatic conditions to predict the behavior of the systems and apply the appropriate control inputs in advance. Therefore, coupling PCM and MPC-based systems could result in energy savings and thermal comfort improvement in buildings. There is wide interest in PCM and MPC-based building systems by researchers, the construction industry, energy policy makers and home owners. The global PCM market is estimated to grow from $460 million in 2013 to $1.5 billion by 2019. However, the thermo-physical properties of PCM-enhanced materials and their effective building integration have not been fully understood. Further research on development of more robust and reliable algorithms is needed to address challenges that inhibit commercial feasibility of MPC-based technologies. The objective of the proposed research program is to develop optimal design strategies and solutions for integrating PCM and MPC-based systems into buildings that will promote and support changes in the national building codes and the wider use of these technologies. In this 5-year cycle, five students will be trained through a series of innovative laboratory experiments, field studies, and modeling exercises to become Canada's future experts in latent heat and advanced HVAC control technologies.