Simulation and Feasibility Study on a 'Renewable Energy House' with a Geothermal Heat Pump-Powered Floor Heating System in Cold Climate Regions

Abstract

An actual renewable energy house, equipped with a geothermal heat pump (GHP)-powered floor heating system was investigated and analyzed. Daily annual monitoring between February 2005 ~ February 2006 and real-time continuous system monitoring within selected periods during the winter season between November 2006 ~ January 2007, were carried out in order to establish the actual performance of the system. It emerged that the GHP-powered floor heating system is sufficient for space heating, with the maintenance of near-uniform room temperatures even during the coldest days in a very cold region like Hokkaido, Japan. About 37% average of the floor heat losses are recoverable and more than 50% of the ventilation heat losses are recovered due to various innovative energy-saving techniques built into the system. Annual heat loss from the house estimated by the numerical simulation showed good agreement with the measured annual thermal demand for room heating. The simulation also estimated that annual running costs and Green House Gas (GHG) emissions reductions of 47% and 49% respectively, can be realized with this system compared to an equivalent conventional system. A detailed cost analysis for the GHP-only system revealed that if the cost of fuel oil increases by about 50% from the current value of ¥80/L, then the payback period for a GHP-powered renewable energy system is about 14 years. This payback period reduces to about 10 years if 30% of the initial cost of the GHP-powered system is externally funded.