Influence of Climate on Open Earth-air Heat Exchanger Potential

Space heating and cooling constitute significant energy demands in buildings. The interdependence between climate and heating and cooling energy usage makes this sector a prominent candidate for climate change mitigation as well as making it susceptible to climate change impacts. Earth-air heat exchangers (EAHE) have the potential to provide heated or cooled air to buildings by allowing for heat exchange between the subsurface and supplied ambient air, hypothetically reducing energy demands for space heating and cooling. However, the system is naturally tied to the climate as it relies on both air and subsurface ground temperatures. Therefore, to ¬recognize the feasibility of these systems and their capacity for becoming tools for climate change mitigation, the influence of climate on these systems require further understanding. The influence of seasonal variations in air and subsurface temperatures were gauged for Canadian climates to understand the impacts of assuming temporal homogenous ground or typical weather conditions. Heating potential was less dependent on the timing of seasonal variations when compared to cooling potential, with ground temperature changes exhibiting a heightened effect. This emphasized the importance of parameterizing temporally heterogenous ground surface conditions for estimates of EAHE potential. The importance of daily air temperature behavior was investigated through the temporal decomposition of surveyed air and ground temperatures from an EAHE system employed in Aichi, Japan. The reliance of cooling on the diurnal variations in air temperature implied EAHE cooling may be susceptible to increases in overnight/morning temperatures when system cooling is least favorable. Finally, ‘future’ EAHE potential was estimated by pairing a climate driven approach with climate change scenarios. Projections of geo-climatic suitability showed EAHE systems can continue to be useful in temperate climates, with a more balanced heating and cooling demand, despite an evolving heating and cooling regime. Further work should endeavor to incorporate the climate influences highlighted in this work to create a comprehensive climate-based approach for estimating EAHE. Ultimately, stakeholders looking to harness the benefits of EAHE systems should consider climate effects, avoiding oversimplifications, when estimating EAHE feasibility for present and future conditions.Ph.D