Ground heat pump in combination with discrict heating for a multi-dwelling building in Gävle

Abstract

Environment has become a major concern for society, which awareness of the importance of an environmentally respectful development has been growing during the last decades. Economic reasons have encompassed this transition to a more planet friendly conception of human development. In fact, this transition has been parallel to the growing prices of fossil fuels, facing a clear perspective of a shortage on its availability, insufficient to cope with a growing demand in the near future. Within this context, the role of renewable energies in order to stop depending on fossil fuels and to reduce greenhouse gases emissions has become crucial. Because of its climate, heating represents a major source of energy consumption in Sweden, accounting for almost 60% of the residential and services sector energy use. Maximizing the efficiency of heating systems and using renewable, environmentally friendly and economically sustainable sources of energy may have an enormous impact on both environment and economy. In this thesis the use of district heating and ground heat pump for a multi-dwelling building is evaluated, both from the economic and environmental points of view. Both are recognized to be efficient heating systems, allowing important savings of other sources of energy, and respectful with the environment. An installation combining both district heating and ground heat pump, for a multi-dwelling building in Gävle has been analyzed. Different scenarios have been considered, and results obtained show that when installing a ground heat pump, both economic savings and CO2 emissions reduction are obtained. Annual economic savings account for 16,8% when providing 60% of the thermal energy with the ground heat pump, and considering the investment associated to the recent installation of a new heat pump (in the case studied, boreholes were already drilled), the payback time is 7,4 years. CO2 emissions reduction for a normal year reaches 34%. However, if we look at the wider picture of electricity and heat production from a community (local, regional, national or even international) point of view, several considerations have to be taken into account, which are discussed in the report.