Environmental evaluation of an air-conditioning system supplied by cooling energy from a bore-hole based heat pump system

An evaluation of the environmental impacts of an air-conditioning system which uses a bore-hole system for heating and cooling is the aim of this case study. To facilitate the evaluation, the bore-hole based air-conditioning system is compared with a reference system that uses a more traditional source of heat (district heating) and cooling energy (refrigeration). Environmental impacts of the system are examined by the life cycle assessment (LCA) method, including the weighting step. Results show that the bore-hole based system performs better in three of the four impact categories investigated: acidification, eutrofication, and global warming potential (GWP) with a 100-year horizon. This is mainly due to the fact that it uses less material in the production phase and less operating energy during the user stage. However, in the category of photochemical ozone creation potential (POCP), it performs four times worse than the more traditional system. Nevertheless, the overall environmental impact of the bore-hole based system, evaluated by common weighting methods, is better than the more traditional system. The most dominant environmental impact of both systems arises from the operating energy, although the energy use in the building studied is low. (C) 2007 Elsevier Ltd. All rights reserved.