eZeit Ingenieure gives a 1930s housing co-op in Berlin a sustainable and modern energy makeover.

WDO discovered eZeit Ingenieure when they announced they were the recipients of a special European award, Best Solution for building Renovation at the 2017 Heat Pump City competition held in Brussels, Belgium. The competition is held annually by the European DecarbHeat initiative which aims to bring the major players of heating and cooling systems in Europe to implement practices that will significantly reduce carbon emissions across Europe by the year 2050. We chatted with Johanna Kiesewetter, one of eZeit’s architects who worked on the innovative award-winning project.

Q: Can you explain the project to us?
The project is called Garden City Lichtenfelde and it’s a housing co-op that includes many buildings built in the 1930s that were in dire need of refurbishing. The challenge was to find a way to make the buildings energy efficient but in a sustainable and socially responsible way in order to justify the increase in rental fees. We transformed the heating systems so that not only the co-op members benefited by saving money, but also the environment by reducing the amount of carbon emissions. Often these types of systems are only installed in newly built buildings, so this project, in a way, proves that even old buildings can be adapted to use more efficient and modern energy systems.


Do it for the 99% of people who can’t afford it and not just for the technology freaks and the rich.

Q: eZeit Ingenieure was recently awarded a special prize for the Garden City Lichtenfelde project at the Heat Pump City award ceremony in Brussels. Why was this important?
The award is very important because it proves that it’s possible to make old buildings sustainable with renewable energy, which is very important for the future. These buildings won’t be renovated again for likely the next 50 years, so it was important to do it correctly now and save on carbon emissions. We want to change the mind-set that you can only implement modern energy systems in new buildings. It is possible to change the energy system so that it has a more positive impact on the environment and on the social perspective. Do it for the 99% of people who can’t afford it and not just for the technology freaks and the rich.

Q: How was the project funded?
One of the managers of the building co-op approached eZeit at a trade show because they were interested in adopting a forward-thinking approach for their buildings. The heating costs were very high and they were looking for a sustainable way to reduce them. eZeit helped by applying for funding from the Federal Ministry for Environment, Conservation, Building and Reactor Security (UIP) by providing theoretical calculations that demonstrated a certain energy standard could be attained. We were quite proud because this was the first time the UIP provided funding to a residential project.

Q: What were the sustainable systems that eZeit put in place?
We installed various systems of creating, recycling and storing energy. For example, in the first building we started by installing solar thermal collectors and a buffer storage system that eZeit developed called an eTank which exploits energy sources such as the sun and ground heat as well as exhaust air from the buildings kitchen and bathrooms. Over the 5 years of construction and re-adaptation, we installed: Heat Pumps, a Dynamic Energy Manager (DEM, the brain of the system which distributes the energy from various sources into the heating cycle, depending on temperature requirements and efficiency) and storage systems that were constantly monitored and tweaked, enabling eZeit to further optimize the energy consumption and as a result, improve on the investment. I’m happy to say that we were able to achieve a primary energy demand of 15kWh/m2a which already surpasses the German (40kWh/m2a) and European (30kWh/m2a) Climate Protection goals for 2050!

Q: Aside from implementing Heat Pumps, what new systems did eZeit develop?
The Exhaust air heat pump was developed by my colleague Dietmar Deunert. It uses the stale air inside the apartments to create energy. A ventilation system constantly draws exhaust air from the bathrooms and kitchens down to the basement. This stale air is then recycled into energy. Actually, 25% of the exhaust air was converted into energy for the buildings.

Q: When did the project start and when will it be completed?
We started the project with the first building in 2013 and will complete the renovations and construction on two more buildings this year and three next year, for a total of 18 buildings, so approximately 400 homes will have been improved by 2018. The temporary displacement of the tenants (for about 6 months) was justified to them during an information session by the savings in energy costs, plus they also benefit from a newly renovated unit.

Q: What other accomplishment of the project are you proud of beside the sustainable energy system?
We also added a fourth floor of modern family units to all 18 buildings. Since the previous units were quite small, it meant that the population was mostly single persons of a certain advanced age. These new homes brought an entire new generation to the community.

Q: What is the next big project for eZeit?
A newly-constructed sustainable suburban neighbourhood just South of Berlin for 5000 families. A kind of city-within-a-city of the future.

About Johanna Kiesewetter
Johanna Kiesewetter was a freelance architect with eZeit Ingenieure from 2008-2012 and was hired full-time when the Garden City Lichtenfelde project was launched. Her roles in the Lichtenfelde project were: design, execution, energy optimization and construction management.

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