Central Europe is, especially in the residential sector, a region using mainly hydronic systems with static heat transfer surfaces, which operate noiselessly and with slow air movements. Cooling is - as yet - not required. This implies that air-heating systems are not very common in Austria. However, new improved building standards may change this situation, because the specific heat load is significantly reduced. In the building sector, both energy savings and a reduction in C02 emissions can be achieved relatively quickly.
In a way most heat pumps recover or reclaim heat energy for space heating and cooling, water heating or process heating. In the building sector, the natural heat sources which heat pumps transfer to useful heat, such as outside air, the ground, ground water and sea/lake/river water are in fact all heat sources that consist of solar heat and cannot be directly used for heating due to their temperature. Hence, one can argue that heat pumps which use these sources are (solar) heat-recovery devices.
The purpose of this project was to evaluate duct sealing as a means of reducing the energy consumption of hot air distribution systems in central Pennsylvania houses. Five houses were studied, all of which were heated with forced-air electric heat pump systems. During the winter of 1995, the heat pump energy consumption, supply air temperature, and the temperature at the thermostat were monitored continuously for approximately two months prior to the duct retrofit. A test also was performed to measure the leakiness of the ductwork.