Church renovation "Heilig Geist Kirche Ergenzingen", Rottenburg, Germany

The tent shaped construction from the 1960s did not offer too much comfort so far: darkened wood panels on the ceiling, ageing face concrete and the sluggish floor heating did not achieve room temperature in winter beyond 13° C, because lack of insulation losing heat to the ground.

So, a concept for increased comfort was the task for Transsolar, with the annual energy consumption of 265,000 kWh for heating expected to decrease – or at least result in some warmth in winter. An overall renovation was out of the question due to the costs, but it is important to understand that the use of a church does not correspond to that of a residential building. Therefore, the idea was to implement heating only in areas where people usually are located.

The top layer of the floor comprising of old bricks had to give way for an insulation towards the ground and for the modern underfloor heating in the screed of the area where the pews are, ready to heat the “congregation island” on demand. Bright terrazzo coatings blend well with the new radiant heat. In case of a very cold winter, the church benches can additionally be heated electrically, radiators were unwanted.

The new underfloor heating also has potential for future expansion. Once the funds for further refurbishment are there, photovoltaic modules could deliver energy from the roof, as suggested by Transsolar. The steep slope facing South is well suited well for PV. The energy generated could then do both, directly feed the pew heating and provide a heat pump to gain free heating energy, e.g. from the air outside.