An investigation into the financial and environmental suitability of ground source heat pumps for residential use in Ireland

Abstract

A ground source heat pump (GSHP) extracts heat energy from the ground for use in space and water heating systems. A GSHP requires some electrical energy to operate, but is capable of extracting up to four times as much heat energy from its source as the initial electrical energy input. The purpose of this study is to examine the suitability of ground source heat pumps (GSHPs) for use in residential heating in Ireland, from certain financial and environmental aspects, as outlined below. Examination of the suitability of GSHPs for use in a group of privately-owned houses found that the optimum array is an array with individual collectors and individual heat pumps. Though this option was found to be 36% more expensive than an array consisting of a shared collector and shared heat pump, low running costs and the avoidance of complications due to shared ownership make the option acceptable in the long term. Long-term cost comparisons were carried out between GSHPs, natural gas heating and oil-fired heating systems in a single large (185m2) house. It was found that natural gas space heating system is 8% cheaper than a GSHP system over a 20 year period. Oil fired systems are more expensive than both natural gas and GSHP. A comparison of CO2 emissions from GSHPs, natural gas and oil-fired systems found that GSHPs are approximately 15% cleaner than the equivalent natural gas system, and 41% cleaner than the oil-fired equivalent. If there is an accessible seawater source available, it would be the best option as a heat source, notwithstanding the fact that a corrosion-resistant heat exchanger would be required. The benefit comes from the fact that an open-loop collector can be utilised, rather than a closed loop system.