Outdated heating systems with low efficiency are considered energy guzzlers and can drive up heating costs considerably. This is why the operators of Christliches Seniorenzentrum Gladenbach GmbH were also looking for a modern solution. "Previously, our annual consumption was around 1.4 million kilowatt hours of natural gas. We wanted to reduce this considerably, which is why we turned to Stadtwerke Gießen," says Managing Director Wolfgang Stolz. The recommendation from energy consultant Oliver Kisignacz at SWG was: a combined heat and power unit (CHP) plus two condensing boilers. Wolfgang Stolz was convinced by the proposal, primarily because of the calculated savings: "With this combination, we expect to reduce our primary energy consumption by up to 25 per cent."
Small power plant generates heat and electricity
Between June 2011 and February 2012, Stadtwerke Gießen converted the heating system for the facility's five houses and optimised the distribution of heating energy via the heating network.
A combined heat and power unit now supplies the residents with heat. "But the CHP can do even more," explains SWG project manager Willi Schwarz: "Based on the principle of combined heat and power generation, the system also produces electricity at the same time. This increases efficiency considerably." The 80 or so residents and operators of the senior citizens' centre consume a large proportion of this low-cost electricity themselves. If the CHP unit generates more electrical energy than the centre needs at certain times, this electricity is fed into the public grid.
At so-called peak load times during the winter months or in the morning hours, the CHP unit's heat output of 95 kilowatts (kW) is not sufficient. "That's why we always install additional gas condensing boilers, which can provide a larger amount of heat at short notice," explains Willi Schwarz. At the senior citizens' centre in Gladenbach, SWG has installed two additional gas condensing boilers with a total output of around 500 kW. The project manager at Stadtwerke Gießen assures: "They are also very efficient and reduce consumption massively compared to outdated systems."