Episode 2:
Problems with glass buildings
Experience has shown that more glass leads to even more shading and more frequent use of the shading. Unfortunately, people leave the shading down even when the sun has long since stopped shining through the window. Not only is there no light behind the shade, but there is also no view. Since the eye focuses on the straight line, a view through slats is always severely impaired. This is even clearer with verticals – the eyes are next to each other and not on top of each other. Even low-contrast sun protection films are usually left open a crack in practice. What counts is what you can see and how beautiful it is, not how large a “panoramic” window is.
Of course, large glass surfaces make sense in mountain restaurants or with other stunning views, but not in an office in the city. If there is a power cut, the shading can generally not be used. In the event of a “heat blackout” – a power failure at low tide, high cooling load and no wind in the evening peak, when even photovoltaics no longer deliver – rooms that are not shaded in this way must either be temporarily shaded outside or abandoned. An inquiry in several hospitals has shown that the shading is usually not secured by the emergency power supply. A “heat dome” like the one in Canada in 2021, when the sun shines for 16 hours in June, can bring temperatures well over 40 °C to our cities. This occurs very rarely, but can be dangerous if there is a lack of preparation. 
Floor-to-ceiling glazing is also not practical unless there is a garden or swimming pond directly in front of it. The larger surface area leads to faster overheating, cools down more in winter even with triple glazing and leads to a higher heating requirement and therefore relatively dry air. This causes the most frequent complaints in offices in winter. As soon as the shading is down, there is no view – unless the window ends at sill height and a gap remains free. South-facing windows with projecting parts of the building above would be ideal, so that the summer sun cannot enter. As it often reaches 30 °C from April until October, it is still necessary to provide external sun protection, which is not needed if the windows are cantilevered, at least when the sun is high. More expensive window cleaning and more frequent repairs to shading are further consequences of excessively large glass surfaces.
In addition, the peripheral area of the visual field is optimized for motion perception. Only 4 % of the eye can see clearly. If only the screen is close to a window that reaches down to the floor and 20,000 cars are moving on the road below for eight hours (normal main road, busy road in cities), the brain has to block out 20,000 interfering impulses. The eye, as the part of the brain that is turned outwards, essentially determines the quality of screen work. If it is overloaded – and glare is often present – concentration decreases and the error rate increases. Looking parallel to the window still lets too much light into the eye. Ideally, a table that extends into the room or is set at a slight angle allows “room control” – no one “falls on your back” and glare is avoided.
For reasons of protection against heat and cold, a revision of OIB Guideline 6 with a stricter U-value for windows and transparent components would be desirable so that triple glazing becomes or remains standard for larger glass surfaces. There is still a drop in temperature and massive radiation asymmetries that make “the space at the window” unusable in the height of winter (so the table is then unfavorably far from the window all year round).
District heating
Furthermore, from the point of view of environmental medicine, district heating without CHP is a waste. Heat pumps need electricity in winter and, even in poorly insulated old buildings, can achieve an annual coefficient of performance of over three with a good design. In the Danish capital, for example, the biomass boilers only start up when the wind supplies too little electricity. The heat generated goes into two 500,000 m³ hot water storage tanks, which can release heat as required. We will need wood for buildings, renewable raw materials such as clothing or plastic substitutes on a large scale and should not have to burn it for heat in the summer.
