Seasonal sensitivity to atmospheric and ground surface temperature changes of an open earth-air heat exchanger in Canadian climates

Abstract

Open earth-air heat exchangers (EAHE) have an inherent relationship with their surrounding environment, relying on the natural contrast between ambient air and subsurface temperatures. This work explored the seasonal sensitivity of open earth air heat exchanger systems to variations in these temperatures. Utilizing 492 weather files in Canada, the heating and cooling potential of open earth air heat exchangers computed using a climate-based approach were compared for different seasonal variation scenarios. Heightened sensitivity to seasonal changes in ground temperatures relative to air temperatures were observed. These effects expectedly decreased with depth. Heating and cooling potential sensitivity to seasonal variations in air temperatures are dependent on the timing, often observing the greatest influence during peak demand periods. Binning by climates identified that regions with a greater mix of heating and cooling potential were more susceptible to seasonal variations. These results also suggest improvements to the heating potential in Canada can be improved by increasing ground surface temperatures outside the summer season, with little influence on the cooling potential. Understanding the interaction between open earth air heat exchanger systems and their environments can ultimately help outline limitations and design solutions specific to their implementation in Canadian climates.