22 May 2008
Since recent years cooling in office buildings is increasing due to higher internal
heat production and higher thermal comfort requirements. This results in a higher electricity
demand. Vertical borehole heat exchangers (BHEs) with a heat pump can reduce the
primary energy consumption and CO2 emissions if correctly designed. This paper presents
simulation results of a whole integrated building and HVAC TRNSYS model with 90, 100 and
110 boreholes. The results are compared with a predefined “reference” installation defining
energy savings, environmental benefits and economical results.
A primary energy saving and CO2 emission reduction of 31% can be obtained compared to
the reference installation. Attention should be given to the borehole filling during the
installation process. The natural cooling fraction increases from 48% to 61% by decreasing
the borehole resistance. The operational costs are higher for the reference installation (86%)
than for the BTES (Borehole Thermal Energy Storage) system (73%). Over the lifetime of the
system the GSHP and BHE is a far more economical choice than the reference installation.
The recent interest in renewable energy is expected to further enhance their application.