ESCSH developed a district heating system using both pulse heat and solar panels in order to reduce heat losses in supply pipes and supply low-energy houses in an energy efficient way.
ESCSH equipped 20 low-energy houses in the Cooperative Society Hjortshøj near Aarhus with a solar collector and a storage tank. Each house was also connected to the local district heating supply. In regular district heating the heat flow in form of hot water or steam is continuous and a considerable amount of heat gets lost when consumption is low (and due to the slower flow, the water cools before it reaches the consumer).
In order to attenuate the energy loss, a so-called pulse heating was applied to the 20 houses: hot district heating water is sent in pulses. For a 3-4 months summer period no heat is sent via the district system, but necessary heat is provided by local solar heating.
The heating pulses are regulated by a timer that is set to four hours a day for the warmer periods, increased to twelve hours a day for colder periods and providing a permanent heat supply for the coldest winter periods. A second regulation stops heat supply to the houses when the tank is warm – based on the thermostats in each house's storage tank. The same heat storage tanks are used to store both solar heating and heat from the district heating in order to ensure heating between the heat pulses. Thanks to the pulse heating technique, total savings amounted to about 50% of heat losses in the local heat supply network. The system also allows heat supply to be scheduled for the hours of the day, where heat is cheapest or most environmental, for instance from a large heat pump driven by wind power.