22 May 2008


In 2006, two large field test campaigns of newly installed heat pumps have been
launched under the direction of the Fraunhofer ISE. Each project deals with the
measurement of a large number of heat pump units under real operating conditions in onefamily
or multiple-family-houses. Values of volume flows, temperatures, heat quantity and
electricity consumption are collected at relative high time resolution (every minute). The data
are sent to Fraunhofer ISE headquarter on a daily basis and automatically checked with
respect to their plausibility. The first phase of the projects was dedicated to the choice of
adequate test houses with heat pump units, to the installation of measurement and storage
devises and to the verification of their proper functioning. The first outcomes of the “Heat
Pump Efficiency Project” confirm a high efficiency of the ground-source heat pumps. The
assessment of the measurement data for heat pumps providing both space heating and
domestic hot water supply, obtained during the first months data acquisition including a
heating period, reveals a seasonal performance factor (SPF) of approx. 3.7 for ground
source heat pumps, 2.8 for air-to-water heat pumps and 3.4 for water-to-water heat pumps.