Window in Wall: Back to the Future

In order to get to a carbon neutral building stock – which is e.g. required by the EU Carbon roadmap by 2050 – our efforts need to be smart and holistic on all scales of design. At the same time, it is essential that a transformation process leads to healthy, comfortable and inspirational environments – indoors as well as outdoors. Additionally, it is necessary to re-think the approach towards environmental quality. Over the past decades a steady state and homogeneous environment was considered comfortable and glass buildings became international style. In order to deal with the problems of all glass buildings, facades solutions and mechanical systems became sophisticated machines, which adapt to the constantly changing outdoor environment. Building controls, sensing and actuators became crucial for a comfortable and somehow energy efficient operation. However, more and more one recognizes that this approach doesn’t provide user satisfaction nor excitement. The complexity leads to an operation, which is extremely sensitive to so called uncertain boundary conditions and imperfection in construction and operation. As consequence, one can see significant performance gaps between design and real-world operation. That’s one of the reasons why New York City mayor Bill de Blasio, on April 2019 in a press conference announced a plan to ban construction of glass and steel high-rise buildings, in a major bid to tackle climate change. In order to decarbonize our buildings, it is essential to design buildings towards robustness and longevity. Robust optimization is a proven design method - used in other industries – which need to be adapted towards the needs of the building industry. A definition of uncertain boundary conditions allows to find a robust optimum. This leads to a building design, which is less dependent on systems, which are very likely to fail over a certain lifetime. Therefore robust optimized buildings aim for reducing the complexity in facade and mechanical systems design, which ultimately questions window to wall ratio.