GSHP value rising
28 March 2011 SOLAR TODAY solartoday.org
THERE’S A LOT TO LIKE ABOUT GROUND-SOURCE HEAT PUMP (GSHP)SYSTEMS. They’resustainable
and proven in both residential and commercial
buildings. Because the earth provides a more
favorable heat source and heat sink than ambient
air, GSHPs are one of the most efficient technologies available for space conditioning and water
heating. Yet, recent studies reveal, less than 1
percent of U.S. houses use a GSHP system, with
economics cited as the major barrier to broader
use.1 Improving the economics requires that we
reduce installation costs, improve system performance or both. That is the aim of a research project Oak Ridge National Laboratory (ORNL) has
undertaken with several partners.
To reduce costs, we’re evaluating two technologies: (1) a foundation heat exchanger (FHX),
which applies only to new construction or additions to existing homes; and ( 2) a ground-source
integrated heat pump (GS-IHP), integrating
space heating, space cooling, on-demand dehumidification and water-heating functions into one
piece of equipment. The GS-IHP, which applies
to new construction and retrofits, also promises
significant improvements in performance.
To reduce the cost of ground-source heat pumps, oak Ridge National Laboratory (oRNL) and its research
partners are testing two technologies — the foundation heat exchanger and integrated heat pump — in
the houses pictured above, built by Schaad Cos. in oak Ridge, Tenn. Advanced envelope designs and
energy-efficiency strategies are built into the houses, which will be used for research for several years
before they are sold and occupied by their owners.
A little more than a year into research demonstrating the FHX, working with a state-of-the-art GSHP unit, it has maintained comfortable temperatures for household heating and
cooling. Early estimates indicate that when
implemented at scale in the test region of East
Tennessee, the FHX approach may be feasible
at $1,000 per ton — a fraction of the cost of the
outdoor portion of traditional GSHP systems.
testing the fhX concept
Why do GSHP systems cost so much more
than conventional space-conditioning and water-heating systems? The cost premium is primarily
Although we’re still gathering performance data
for the GS-IHP prototype, our technology partner plans to launch a product line based on the
technology later this year.