Analysis of thermo-active foundations for office buildings

Abstract

Ground source heat pumps (GSHPs) have been widely used to heat and cool buildings. However, the installation costs of GSHPs with vertical boreholes can be significant and may result in reducing their cost-effectiveness relative to other conventional heating and cooling systems. As alternatives to GSHPs, thermos-active foundations (TAFs) have lower installation costs but similar thermal performance. This paper provides a simplified analysis approach using the G-function method specific to TAF systems. In particular, G-functions have been determined with various thermal pile shapes to predict the short-term and the long-term performance of TAFs. As part of analysis outlined in the paper, the G-functions are integrated in a whole-building simulation tool to compare the energy efficiency and cost effectiveness of TAFs and GSHPs to conventional VAV systems for office buildings in three US climates. It is found that TAFs have slightly better energy efficiency but are significantly more cost effective than both GSHPs and variable air volume (VAV) systems in all the US climates considered in the analysis.