Working actively with glass and sun protection
The sun beams in through the adjacent window as Helena Bülow-Hübe, PhD and Head of Environment and Energy at FOJAB arkitekter, talks enthusiastically about her area of expertise - daylight, solar heating and glass in facades. She talks about the great opportunities for development and improvement, both economically, technically and aesthetically. But according to Helena, a change in attitude is required to get there.
- We need a more active approach to these issues. It is common to write a general U-value requirement for windows. It then applies to all facade surfaces, regardless of the direction of the wind, sun/shade conditions and room function. In line with this, the same solar control glass is chosen for the entire facade and usually the entire building. Nevertheless, there may only be a small part of the facade that is unshielded and has a large passenger load, for example with a conference room behind it. But that situation still becomes the design basis for the whole building.
Sunscreen glass is used indiscriminately
- Technical performance facts are often discussed in the design process. The ventilation consultant calculates a g-value, solar transmission, for the glass. This is then written into the documents as a general requirement for the building's windows, perhaps at a stage when it is difficult to see the consequences. What will be the technical performance? What is the impact of this requirement on the aesthetics of the façade and the availability of daylight indoors?
We discuss the importance of taking a holistic approach and using solar shading intelligently. Helena Bülow-Hübe says that solar control glass is often used carelessly. This can result in facades that give a dark and sad, even rejecting impression and she highlights a concrete example: "An office building was designed with a glazed entrance with a reception behind it on the ground floor. The intention was of course to give an inviting and welcoming impression. But the same effective solar control glass had been used throughout the building, and the result was that visitors only saw their own reflection when approaching the entrance.
- This can unfortunately also be seen in commercial contexts, with shop windows that reflect more than they provide daytime visibility, and thus do not serve their purpose, says Helena. The solution lies in working with sun protection and the choice of glass in a differentiated way. Different conditions in different parts of the facade may result in varied solutions. You do not have to meet the higher technical requirement where it is not needed and thus have the opportunity to bring in daylight. This allows the glass to have the transparency that was intended.
There is much to gain
- Where the load is high, choose a suitable surface-mounted sunscreen. This can be blinds or fabrics. In one project we used insulated sliding window shutters with great success. This makes it possible to choose a clearer glass that lets in daylight, which also reduces the need for artificial lighting during the day.
- Sometimes you want both internal and external sun protection. The interior can be used in winter to take advantage of the solar heat gain. In some situations, the internal sun protection is also needed as glare protection because the external sun protection is not really sufficient.
Working in a differentiated way with glass and sun protection in the facade means a design challenge and the possibility of more elements to play with. FOJAB arkitekter has the expertise to work in this way, both with technical analysis and design. There is much to gain in terms of comfort, energy and aesthetics. And hand on heart - who is really interested in paying for product features that have no function?