Feasibility of thermal load control from electrochromic windows for ground coupled heat pump optimization

Abstract

The concept of designing a ground coupled heat pump (GCHP) system as a rechargeable source of energy by implementing supplementary heating and cooling load devices to dynamically balance building energy loads has recently been introduced. This research presents a novel design of integrating electrochromic glass window controls with a GCHP system for long-term optimization and sustainability. A building energy model was developed and simulated with the solar heat gain coefficients of 0.41, 0.25, 0.15, and 0.09 to model electrochromic glass windows. The energy model outputs were used for ground heat exchanger model simulations which analyzed 20-year temperature trends and system efficiencies. The results showed the integrated GCHP system with electrochromic windows was feasible and a conceptual control sequence and design was developed. The annual cooling demand decreased by 32% between the clear glass and fully tinted state. It was recommended to increase the ground heat exchanger capacity to 200 boreholes at 45.7 m in 2040 to prevent overheating from projected climate change. The average system coefficient of performance was 7.6 for the fully tinted window state. The integrated GCHP system reduced CO2 emissions by 30% and the 30-year NPV was US$142,273.65 cheaper compared to a conventional boiler and chiller system.