Initial Situation
‍The four buildings with a total of 24 residential units, built between 1955 and 1957, formed the starting point for the modernization. The lettable area of the building stock comprises approximately 1,600 square meters. The original energy supply was decentralized and based on natural gas. The balconies and loggias existing at the time no longer met current standards. The project's goal was the energetic retrofitting of the building envelope to the Efficiency House 55 EE standard, alongside the functional upgrade of the apartments through new balconies and adapted floor plan usage.‍

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Implementation
‍The ecoworks facade system was utilized for the serial retrofitting. In addition to the new facade envelope, the roof and basement were insulated. The old decentralized gas heaters were replaced by a central system with air-source heat pumps, which now handles the heating supply. Hot water is provided by decentralized tankless water heaters. A newly installed ventilation system with heat recovery permanently ensures air exchange and energy savings. Photovoltaic systems were installed on the roofs as full feed-in systems to meet the requirements of the EE class.In some buildings, the former loggias were integrated into the living space. Additionally, all apartments received new freestanding balconies. Furthermore, the entrances were equipped with canopies including lighting and motion detectors, as well as new mailbox systems with intercom functions.‍

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Result
‍The retrofitting achieved an energy-efficient building standard. By factoring in subsidies, the costs for the Efficiency House standard remained in line with those of a conventional retrofit. The use of industrial prefabrication and the concentration on exterior work reduced the disruption for residents to a minimum during the construction phase.

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