Geo-climatic applicability of earth-to-air heat exchangers in North America

Abstract

Earth-to-air heat exchangers (EAHX) systems have the potential to provide low energy heating and cooling in line with current appeals for energy efficiency and reduction. The lack of a geo-climatic description of EAHX applicability in North America, useful for pre-design decision making, motivated the creation of the Eahx geo-CLImatic Potential Script, or “ECLIPSe”, capable of describing EAHX applicability by comparing the cooling and heating degree hours prior to, and after being conditioned by a virtual system. The applicability was derived for varying values of system effectiveness and depth as well as soil surface conditions and thermal properties. Improved system effectiveness enhanced system applicability, particularly for those climates with either a dominant heating or cooling need, while increased depths appear to have diminishing returns past 2.5–3 m. EAHX systems are less sensitive to soil thermal properties and surface conditions. The results indicate EAHX systems are best suited for temperate climates where there is a balance in heating and cooling needs relative to climates which are dominated by either need. The approach can be further utilized to provide a preliminary regional assessment of EAHX applicability for different areas and future climates useful for designers looking to implement low energy technology.