Three years’ performance monitoring of a mixed-use ground source heat pump system in Stockholm

Abstract

The student center, Studenthuset, at Stockholm University in Stockholm, completed in the fall of 2013, is a thoroughly instrumented mixed-use 6300 m2 four-story building. Space heating and hot water are provided by a ground source heat pump (GSHP) system consisting of five 40 kW off-the-shelf water-to-water heat pumps connected to 20 boreholes in hard rock, drilled to a depth of 200 m. Space cooling is provided by direct cooling from the boreholes. The Studenthuset building monitoring project is part of the IEA HPT Annex 52 – Long-term performance measurement of GSHP systems serving commercial, institutional and multi-family buildings. This paper presents results from three years of measured performance data to calculate the long-term performance of the Studenthuset GSHP system. A number of performance indices are calculated and presented to describe the short-term and long-term system performance for selected system boundaries. Seasonal, monthly and binned performance coefficients for both heating and cooling operation are presented and discussed. The Legionella protection system, hot water continuous circulation system, and internal heating/cooling distribution system reduce the system energy performance.