The economic and environmental optimisation of integrating ground source energy systems into buildings

There are currently two main drivers for the consideration of ground source energy systems in the built environment in the UK. Firstly, building occupiers and owners are becoming increasingly concerned at rising energy prices whilst building designers are also required to reduce, due to European and national and local legislation, the operational CO2 emissions from new and existing buildings. This paper considers the application of Bivalent (dual fuel) ground source heat pump heating and cooling systems as a way to reduce the installation costs whilst also providing considerable economic and environmental savings. A case study building is used to demonstrate the importance of optimising ground loop heat exchanger length, considering differing future energy prices and the chosen appraisal period. An incremental approach is used to consider the relative benefits of increasing the size of the GSHP. Designers can also be misled by the assumption that by sizing a GSHP system to just meet the legislative targets the most economically sized system will be installed. The optimum system shows a >60% reduction in the capital cost vs. a peak sized GSHP system whilst still providing >70% of the respective economic savings and CO2 reduction.