22 May 2008

GLOBAL WARMING IMPACTS OF GROUND-SOURCE HEAT PUMPS COMPARED TO OTHER HEATING AND COOLING SYSTEMS


Heat pumps can significantly reduce primary energy use for building heating and
cooling. Geoexchange or ground source heat pumps (GSHP) utilize renewable energy stored in
the ground near the surface. The renewable component, as high as 65 percent (ground-source)
depending on location (climate), displaces the need for primary fuels, which when burned,
produce greenhouse gases and contribute to global warming. The energy simulation program
DOE 2.1E was employed to model the energy use of a single family residence and office
building in six locations across Canada. Utilities provided up-to-date emission factor data
associated with new (marginal) generation plants in each area.
Significant emission reductions resulted through the application of ground-source heat pumps in
both the residential and small office buildings. For the examples presented here, residential
high efficiency natural gas heating systems produced anywhere from 1.05 to 30 times the
equivalent CO2 emissions of ground-source heat pumps. In the small office building example,
CO2 emission reductions from 10% to 75 % were achieved through the use of ground-source
heat pumps. Even under the assumption of new incremental generation capacity which in most
cases examined here is natural gas plants, greenhouse gas emissions are significantly lower in
buildings with ground source heat pumps.