Payback period for a ground source heat pump system

A Discounted Cash Flow Model has been implemented in this paper in order to investigate the economic impact of ground-source heat pump for heating (GSHP) and cooling in comparison with traditional condensing boiler (CB). The economic model allows the analysis costs and revenues of the two different systems and seeks to provide if the GSHP outperform its conventional counterpart in the long term, taking account for factors as price/cost growth. The analysis has been performed adopting a parametric approach, in which all terms are linked to energy labels, degree-days and Energy Mix Ratios (EMRs), the latter obtained as ratio between the full unit cost of electricity and natural gas paid by householders. Concerning different EMRs, the pay back periods are displayed in decision matrixes, in which energy labels and degree-days represent the row/column variables and allow to compare the benefits of choosing between GSHP versus CB. The results show that higher energy labels have a good profitability ratio between costs and payback periods, and demonstrate that GSHP system does pay off. Lower labels turn out to be interesting when the EMR drops to 0,25 and the gas price goes up to 0,70 €/Nm3. Some considerations are presented to express environmental aspects.