Work begins on the energy-efficient refurbishment of seven buildings in the Franz Liszt Quarter

The owner of the seven older apartment buildings from 1954 is GBO Gemeinnützige Baugesellschaft mbh, a subsidiary of Stadtwerke Offenbach. It is commissioning the work. The refurbishment also involves adding storeys to the buildings. Two new penthouse apartments will be created in each building. The houses will also be connected to the district heating network. GBO is investing a total of around 10 million euros in the energy-efficient refurbishment.

Stadtwerke Offenbach is working here on a further lever to achieve Germany's target of climate neutrality by 2045. The upcoming refurbishment in the residential district is Offenbach's contribution to this. GBO is using the serial prefabrication method for the energy-efficient refurbishment of the outer shell. To this end, the buildings were measured last October using drone flights. A point model was created from the data. The construction company B&O is currently using this to produce the wooden façade modules, including the new windows, in the factory to a precise fit. B&O also built the two new timber hybrid houses in modular construction, which were used to densify the spacious open spaces four years ago.

In addition, the wooden façade itself not only looks good, it is also sustainable thanks to its renewable raw material. It ensures that the houses insulated in this way require less heating in winter and no longer heat up so much in summer.

The serial refurbishment is due to start in June after delivery of the modules. The new façade of each house will then be installed in around three weeks. Conventional renovation would take around three to six months per house, depending on the construction method. And the total of 14 new penthouses, each 60 square meters in size, can also be built in around one month with the prefabricated modules, instead of the usual three months.

These advantages are currently offset by higher costs, but these are compensated for by subsidies from the Kreditanstalt für Wiederaufbau (KfW) for serial refurbishment. Once the work has been completed, the houses will meet the KfW 55 EE standard.

The tenants in the 42 existing apartments will then have to heat less in order to live in a warm apartment. However, the rent will also increase after the refurbishment: on average, the existing apartments will cost around EUR 2.40 more per square meter. This is an increase of around 30 percent, and the new average rent is then expected to be around EUR 9.60 per square meter. The new penthouse apartments will probably be offered for 11.50 euros per square meter.

As part of the work, the old gas floor heating systems and individual gas stoves will also be removed from the apartments. They will then be supplied with district heating. GBO's aim is to heat its properties without fossil fuels in future and to convert to district heating wherever possible. This is also the requirement of the Building Energy Act, according to which every new heating system must be operated on the basis of 65% renewable energy.

This conversion can be implemented in the Franz-Liszt-Quartier without major effort, as a district heating pipeline runs through Weikertsblochstrasse, so that only a connection to a district heating transfer station needs to be made.

The overall package of energy-efficient refurbishment in the district is rounded off by a photovoltaic system on the roof to feed climate-friendly electricity into the Offenbach grid. The tenants will also have new balconies with a larger area in front of their apartments.

All the work is due to be completed by spring next year.