Stiftung Waisenhaus, Frankfurt

Stiftung Waisenhaus – Frankfurt, Germany
Project overview

The Stiftung Waisenhaus (Orphanage Foundation) building in Frankfurt combines social housing with community services. Architects B&V Braun Canton designed a composite window system to achieve high energy performance and occupant comfort in the building’s residential units. The climate in Frankfurt requires both summer shading and winter insulation.

Design challenge

The building needed to provide apartments with ample daylight while preventing heat build‑up in summer. Because the residents include vulnerable populations, thermal comfort and energy efficiency were paramount. Conventional shading systems would have required occupants to operate blinds manually, which might not always happen. A passive solution with low maintenance was preferred.

RetroSolar strategy

The solution is a composite window: the outer pane is white glass, and the inner triple insulation glass contains RETROFlex 25 mm blinds
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. The retro‑reflective louvers reduce the solar heat‑gain coefficient to around 5 % in summer
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. The composite construction allows the louvers to function within the sealed unit, protected from the environment. The distance between the panes provides space for the louvers and improves acoustic and thermal insulation.

Building physics and performance

The combination of white outer glass and retro‑reflective louvers significantly reduces solar heat gains while admitting diffuse light. Tests show that the inner pane remains only 4–6 K above the room temperature, indicating effective thermal insulation
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. The system provides good lighting and views, ensuring that residents enjoy a bright interior without discomfort. Being part of a passive house window system, the composite window contributes to low energy consumption for heating and cooling.

Architectural outcome and significance

The Stiftung Waisenhaus project demonstrates that high‑performance shading can be integrated within social housing without complicating operation or maintenance. The composite window design enables the building to meet stringent energy standards while providing residents with comfort and a connection to the outside environment. The project serves as an example of equitable sustainability, showing that advanced daylighting technology can benefit all building types and demographics.