Residential Buildings’ Foundations as a Ground Heat Exchanger and Comparison among Different Types in a Moderate Climate Country

Lazaros Aresti,Gregoris P. Panayiotou,Georgios Florides,Paul Christodoulides

doi:10.3390/en13236287

Abstract

Shallow Geothermal Energy Systems (SGESs) constitute Renewable Energy Systems (RES), which find application in the residential sector through the use of Ground Source Heat Pumps (GSHPs). GSHPs are associated with Ground Heat Exchangers (GHEs), whereby heat is gained/lost through a network of tubes into the ground. GSHPs have failed to flourish in the RES market due to their high initial costs and long payback periods. In this study, the use of Energy Geo-Structure (EGS) systems, namely, the foundation (or energy) piles and the foundation bed of a residential building in Cyprus, was computationally modeled in the COMSOL Multiphysics software. First, the single-houses’ trend in number of units and area in Cyprus was examined and a theoretically typical house with nearly Zero Energy Building (nZEB) characteristics was considered. The heating and cooling loads were estimated in the TRNSYS software environment and used as inputs to investigate the performance of the GSHP/GHE systems. Both systems were shown to exhibit steady performance and high Coefficient of Performance (COP) values, making them an alternative RES solution for residential building integration. Next, the systems were economically evaluated through a comparison with a convectional Air Source Heat Pump (ASHP) system. The economic analysis showed that the cost of the suggested conversions of the foundation elements into GHEs had short payback periods. Consequently, either using the foundation piles or bed as a GHE is a profitable investment and an alternative to conventional RES.

Highlights

Renewable Energy Systems (RES) have increased in popularity in recent years through a global effort to find alternatives to fossil fuels and reduce CO2 emissions
A notable example of such systems is the Ground Source Heat Pump (GSHP), which takes advantage of the Geothermal Energy stored in the sublayers of the earth
GSHP systems are used for space heating and cooling, where heat is either extracted or rejected to the earth through a network of tubes directed into the ground

Summary

Introduction

Renewable Energy Systems (RES) have increased in popularity in recent years through a global effort to find alternatives to fossil fuels and reduce CO2 emissions. A notable example of such systems is the Ground Source Heat Pump (GSHP), which takes advantage of the Geothermal Energy stored in the sublayers of the earth. GSHP systems are used for space heating and cooling, where heat is either extracted or rejected to the earth through a network of tubes directed into the ground. The demand for RES (and GSHPs) in Europe is increasing as the 2020 EU (European Union) directive of nearly Zero Energy Buildings. GSHPs saw an increase in their world installed capacity between and 2015 of 1.52 times, establishing their position as direct users of geothermal energy [3]

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