For some years now glass has characterized modern architecture like no other material. Provided they are incorporated in an overall planning concept in line with their performance potential, glass materials not only characterize the appearance of faades but also make a decisive contribution to the energy efficiency of buildings. Based on experiences acquired with initial major projects involving a high percentage of glazing, the aspect of thermal protection in summer plays an especially important role today. Solar protection devices compensate for a disadvantage that often goes hand-in-hand with the transparency of glass architecture — much to the architects’ regret — the undesirable build-up of room temperature in summer. The use of the latest generation of coated solar protection glass can substantially reduce but not entirely avoid this effect. By all means, in winter these solar gains are desirable but in summer they can result in unpleasantly high air temperatures in building interiors.
Optimised interplay
To avoid the undesirable heat build-up in interiors, a wide variety of solar protection systems are installed in glass architecture. They are an essential component for the productive interplay between efficient thermal protection, maximum use of daylight and reliable ventilation of interiors. Controlling the complex correlations between external and internal influences on the building in such a fashion that pleasant temperatures prevail indoors throughout the year is one of the biggest challenges for modern glass architecture.
Prof. Anton Maas, head of the Construction Physics Faculty at Kassel University, explained the current issue at the annual meeting of the German Flat Glass Manufacturers’ Association in April 2010. He forecast that solar protection in summer would increase in importance while also stressing the performance of windows and faades as highly efficient energy “winners” suitable for saving massive amounts of heating energy.
Experts principally agree that integral planning is required to efficiently leverage the energy and architectural potential of large-surface glazing in building skins. Planners and faade installers must, where possible, cooperate in the development stages of a project. Only this multi-disciplinary collaboration and the consideration of the given climatic conditions at the location can ensure an optimized interplay of summer-time solar protection, ventilation and heating and/or cooling technologies.
New opportunities through building-integrated PV
Building-integrated — or to be more precise faade-integrated — photovoltaics will also play an increasingly pivotal role in boosting energy efficiency in the future. Although numerous product solutions are already available on the market, installed systems can only be found in isolated cases. The reason for this is a lack of consideration on the part of architects — something which solar industry experts discovered at the international Solar Summits congress in 2009. Even so, PV modules can now be installed as systematically as conventional faade elements made from other materials.
Even today PV elements featuring the latest thin-film technology can be ordered in various colours thereby providing more design freedom for faades. These cells are based on completely different principles to the semi-conductor technology used so far. Since the technologies for their production are very similar to those already used in industrial glass processing, efficient manufacturing is possible. In addition to their use in new buildings, integration-enabled photovolatics modules also have multiple applications in faade refurbishment.
Knowledge of the available glass products and their working principles is imperative for realizing sustainable, energy-efficient glass architecture. Only by considering any glass versions that qualify for a building project can multi-disciplinary cooperation come up with holistic building concepts that live up to the high requirements made by both legislators and building owners.