Rénovation de la Tour d'Habitation Rheinstraße, Karlsruhe, Allemagne

A residential high-rise building from 1963 is undergoing extensive modernization. First, hazardous materials such as asbestos must be removed, followed by updating the building's fire safety and energy efficiency.

The floor plans of the apartments are being altered, and each unit will receive a winter garden expanding the living space through a protected mid-door area. In the unconditioned buffer space, it is warmer in winter when the sun shines than outside. In summer, it serves as an openable balcony, shading the apartment. With the balcony facade constructed on its own support structure, the living area of the building increases from 5,100 m² to 6,100 m².

The closed southwest facade will feature a 447 m² facade-integrated photovoltaic (PV) system that replaces the required facade cladding. This system primarily generates electricity in the second half of the day when electricity consumption in residential buildings is typically higher. Due to the long-life cycle, the symbolic nature, the low share of only approx. 0.5 % of the total project costs and the uncomplicated possibility of integration, façade PV is particularly recommended here. Together with an optional 50 kWpeak PV system on the roof, an amount of energy can be generated that offsets 46% of the annual building operation emissions. The proposal to install a battery storage system and retain the solar yield during the day for the evening and night hours is aimed at using as much of the solar power as possible in the house, increasing self-sufficiency.
The idea to generate wind energy on the roof was considered and wind measurements were taken using a weather station. The results indicate that the economic operation of a wind turbine on the roof is currently still challenging. The data also support the research project of TU Dresden titled "Urban Wind Turbines with High-Performance Steel Rotor Blades."

Hot water provision via heat transfer stations within the apartment eliminates the need to circulate the domestic hot water in the shaft. It is difficult to ventilate the apartments via window frame vents due to the sound insulation values to be complied with. Supply air from the winter garden does not meet the required quality if the glazing is closed. Therefore, an external fresh air duct would be required for each room. Routing exhaust air through the roof would involve significant effort for fire protection and reduce the living area due to the risers. The planned energy-efficient low-temperature heating system is not suitable for heating cold outdoor air in winter. Therefore, each apartment will have a decentralized supply and exhaust air system with heat recovery. Such a system pre-warms the outdoor air through heat exchangers with a heat recovery rate greater than 85% and ensures good air quality regardless of external noise influences. The proposed approach to address these challenges is to create an installation wall with the necessary technology in each bathroom. It is also possible to mount the required ventilation unit in an industrially prefabricated installation wall above the WC flushing tank. Additional benefits include time savings during installation and verified safety with all documentation. The energy demand is thus around 27 kWh/m² per year for (district) heating, including potable hot water, and 31 kWh/m² per year for electricity.

The hazardous material remediation work is expected to be completed in September 2024. The subsequent modernization is expected to take two years.