With our façade design we established a standard that now – 10 years later – is being built everywhere. Based on our analyses, we were able to prove that the heat input from solar radiation can be significantly reduced by making the window reveals slightly deeper. This lowers the operating costs for ventilation and air conditioning, which in the long term makes sense not only for the environment but also for the operator’s budget. The high-quality implementation as a rear-ventilated stone façade is the logical consequence: Its durability and low maintenance requirements minimise operating costs.