Abstract
The more widespread use of Ground Source Heat Pump (GSHP) systems has been
hindered by their high first cost, which is mainly driven by the cost of the drilling and excavation
for installation of ground heat exchangers (GHXs). A new foundation heat exchanger (FHX)
technology was proposed to reduce first cost by placing the heat exchanger into the excavations
made during the course of construction (e.g., the overcut for the basement and/or foundation and
run-outs for water supply and the septic field). Since they reduce or eliminate the need for
additional drilling or excavation, foundation heat exchangers have the potential to significantly
reduce or eliminate the first cost premium associated with GSHPs. Since December 2009, this
FHX technology has been demonstrated in two ultra-high energy efficient new research houses
in the Tennessee Valley, and the performance data has been closely monitored as well. This
paper introduces the FHX technology with the design, construction and demonstration of the
FHX and presents performance monitoring results of the FHX after one year of monitoring. The
performance monitoring includes hourly maximum and minimum entering water temperature
(EWT) in the FHX compared with the typical design range, temperature difference (i.e., Δ T)
across the FHX, and hourly heat transfer rate to/from the surrounding soil.
