Serial retrofit reaches energy efficiency milestone: ambitious 40 EE standard achieved

On 26 April 2023, a beacon project for serial retrofitting was officially completed: the “Wohnungsgenossenschaft am Vorgebirgspark (WGaV) eG” housing cooperative pilot project is the first project in Energiesprong Deutschland’s history to achieve the ambitious 40 EE energy efficiency house standard.

Like many post-war buildings, the multi-storey building at 24-26 Schwalbacher Straße was poorly insulated, heated with gas, and consumed significantly more energy than is technologically possible today. Following the serial retrofit using prefabricated façade, roof and technological modules, the building already meets the high energy standard which will be required by law for new buildings from 2025 onwards.

Not only does the building conserve around 90% of its energy, but with its powerful photovoltaic system, it even generates more renewable energy on an average annual basis than the residents need for their heating, hot water and electricity combined. The 16 tenants are, therefore, completely free from fossil fuels and permanently protected from rising energy costs as a result.

Thomas Meißner, WGaV Board Member, says: "Our example makes it clear that even small market players can work together to achieve great things for climate protection".

The serial retrofit project in Schwalbacher Straße is the result of cooperation between regional partners. The comprehensive retrofit solution was designed by the Zeller Kölmel architects’ firm. The structural and technical planning was conducted by the Stein energy company and implemented by Korona Holz & Haus.

For WGaV, the Köln-based housing cooperative, the serial retrofit project which was implemented following the Energiesprong approach has paid off both in ecological and economical terms: the total cost of the energy-efficient modernisation work amounted to EUR 1.9 million, of which EUR 876,000 was funded through the German government's BEG programme and EUR 235,000 through the EU's North West Europe Interreg programme.

Based on this positive experience, WGaV is already planning their second serial retrofit project. In the immediate vicinity of the completed pilot project, three five-storey apartment buildings, with 30 residential units and a total area of 2,460 square metres, will be serially retrofitted and brought up to the climate-neutral, net-zero energy standard.

The Köln-Zollstock project is the seventh pilot project to be completed which has been serially retrofitted following the Energiesprong approach. A further 95 projects with a total of 10,400 residential units are in various stages of planning, preparation and implementation. Lessons learned from these projects will help the industry to further improve serial retrofit solutions and reduce costs to a level that is acceptable for mass market scaling.

With the Serial Retrofit funding programme and the new BEG bonuses for Serial Retrofits and Worst Performing Buildings, the German Government has created an attractive funding policy framework. As a result, with significantly faster implementation times, serial retrofitting is roughly at the same cost level as conventional energy-efficient modernisation work.

"Whether due to a shortage of skilled workers, mandatory retrofitting for the worst-performing buildings or achieving 65% renewable energy by replacing heating systems, serial retrofits already offer practical answers to the challenges of tomorrow today," says Uwe Bigalke, Head of Serial Retrofits at dena.

Photo dena | Jens Willebrand

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