A design methodology and analysis of combining multiple buildings onto a single district hybrid ground source heat pump system

In this study, the appropriateness of combining multiple buildings onto a single district hybrid GSHP system is assessed. For this purpose, a new methodology is introduced enhancing and utilizing a methodology previously introduced by the same authors for designing hybrid GSHP systems [Alavy et al., Renewable Energy 57 (2013) 404-412]. The new methodology is applied to a utility model of heating and cooling for 100 different commercial buildings, in which a utility or private company installs a larger hybrid GSHP system and then distributes heating or cooling to buildings via a common water loop. The methodology proposed in the present study automatically computes the savings potential associated with thousands of possible building combinations to perform a statistical analysis on the value and potential of the utility model for heating and cooling. It is shown that the methodology can result in reducing the net present value (NPV) of total costs (up to 50%), increasing the potential savings, and still meeting a significant amount of the buildings' heating and cooling demands. This study also shows that for a desired value of NPV savings, increasing the number of buildings combined is only valuable until a certain threshold (which depends on location, weather, building type and building size), after which adding additional buildings to the combinations is not worthwhile. It is also shown that some buildings, for which installing a GSHP system was totally uneconomical, lend themselves particularly well to the utility model and in return, can benefit from a more environmentally friendly geothermal source of heating and cooling.