Heating & Cooling
The Renewable Energy House obtains its complete heating and cooling requirements entirely from renewable energy sources. Using a combination of biomass (wood pellets), solar thermal and geothermal energy, the heating, cooling and ventilation system generates high standards of comfort in the whole building throughout the year. The Renewable Energy House thereby demonstrates that 100% renewable heating and cooling is feasible in a large proportion of Europe’s buildings.
Key elements of the renewable heating and cooling system in the Renewable Energy House:
2 biomass wood pellet boilers (85kW + 15kW)
60 m2 solar thermal collectors : 30 m2 vacuum tubes + 30m2 flate plate collectors
4 geothermal energy loops (115 m deep) exploited by a 24 kW ground source heat pump in winter and in summer, used as a “cooling tower” by the Thermally Driven Cooling Machine in summer
1Thermally Driven Cooling Machine (absorption chiller) - 35kW cooling capacity at 7-12°C
1 cooling tower (46kW)
Heating - Winter operation
In winter, the heating system mainly relies on the biomass (wood pellet) boilers and the geothermal system. The biomass boilers heat the radiators of the main building. The radiators in the back building are heated with energy extracted by the heat pump from the four geothermal energy loops located under the main courtyard. The solar thermal system and biomass boiler heat the same storage tank. Due to shading from neighbouring buildings, the direct “sunlight” solar thermal contribution is low in winter. However, all the “daylight” solar gains in winter will minimise the consumption of wood pellets. During this season, the geothermal system operates on a separate circuit from the biomass and solar circuits.
Cooling - Summer operation
The core of the cooling system is the Thermally Driven absorption Cooling Machine. While conventional cooling machines consume high amounts of electricity at peak demand times, this thermally driven cooling machine is powered from relatively low temperature heat (85° C) and a small amount of electrical power for the control and pumping circuits. The thermally driven cooling machine used in the Renewable Energy House obtains its heat energy from the solar system which is backed up on cloudy days by the biomass boilers. Since solar radiation levels and cooling demands coincide, the solar thermal system is able to provide much of the heat required by the cooling machine. Solar cooling is an ideal application for a solar thermal system. The solar heat coming from the collectors is released by the thermally driven cooling machine as low-grade excess heat. In most conventional cooling systems of this type, the excess heat is dispersed into the environment through a cooling tower. In the Renewable Energy House, the geothermal borehole loops function as a seasonal energy source, absorbing the excess low-grade heat during the summer months. Through the winter operation of the geothermal system, year-on-year overheating of the boreholes is avoided.
System regulation
The Renewable Energy House features an advanced control system that senses the occupation levels and the ambient environment in the individual rooms and adjusts the settings of the heating and ventilation system accordingly.
An automatic monitoring system installed and managed by the company SOLID ensures the ccordination of the different energy sources. The control system enables most of the necessary adjustments to be controlled and performed at a distance. Because of this remote monitoring facility, the regular in-house system maintenance procedures are minimized.
