Sustainability is becoming increasingly important

Jutta, you have been attending glasstec and the special glass technology live exhibition for 14 years now. How have the topics that take centre stage there changed over the years?

Jutta Albus: Many of the issues that manufacturers were addressing back in 2010 are still relevant today – such as the use of large-format glass, curved glass constructions or the production of multi-laminated, load-bearing glass elements. The integration of photovoltaics into building envelopes was also a hot topic in 2010 and remains so today. Nevertheless, there have also been shifts: Sustainability issues are even more important today than they were fourteen years ago.

Does this only apply to the innovations from research and development that will be shown live at glass technology? Or has the topic of sustainability already reached manufacturers to its full extent?

Jutta Albus: Today, no manufacturer can avoid the question of how glass can be produced in the most energy-efficient and resource-saving way possible. The flat glass industry in particular faces major challenges in this area. Take glass recycling, for example: returning cullet to the production process saves energy and raw materials. However, the cullet must be completely free of impurities if it is to be turned into new flat glass. The sorting and treatment processes are correspondingly complex – and the recycling rate for flat glass is still correspondingly low. The situation is very different to container glass, where the quality requirements are lower and recycling has been common practice for decades.

Which new developments in glass and facade technology do you think are particularly promising when it comes to resource-saving construction?

Jutta Albus: Great progress has been made in recent decades, particularly with coatings for thermal and solar control glazing. High-performance solar control glazing is now available that is much more transparent than in the past. Nevertheless, as architects, we must still do our homework – be it in terms of structural solar control or the question of which glass surfaces are appropriate, depending on the use of the building and the compass direction. Large-format triple insulating glazing, for example, weighs a lot, posing a major challenge with respect to transport and installation. Thin glass constructions, which are currently the subject of much research, may help us here. In future, this could also make it possible to create large glass surfaces with good U-values and a comparatively low weight.

Two years ago, you supervised a master's thesis on "The renaissance of the glass block". What potential does the glass block have today, and in which areas of application?

Jutta Albus: From an aesthetic point of view, glass blocks have enormous potential – from the lighting effect they create indoors to the opportunity for using them to create curved building facades. They are rarely used in residential construction, but they are definitely a good option for public buildings, office blocks and research buildings.
However, this is offset by the limited insulation value of glass blocks. One solution could be double-skin exterior wall constructions, such as those used by Swiss architect Roger Boltshauser in his buildings.

In future, the development of recyclable glass block constructions will be indispensable. I don't think that subsequent deconstruction should be the all-important question when designing a building. Instead, long utilisation cycles and the longevity of the building must take centre stage. Nevertheless, from a sustainability perspective, it would be elementary to construct glass block walls without mortar or with removable bonds.

Working with several chairs at the Technical University of Munich, you are currently supervising the research project “Einfach (um)bauen”. What is it about and what solutions are you focusing on?

Jutta Albus: In the project, we are primarily looking at residential buildings of certain ages, which generally have particularly poor energy efficiency and a low standard of insulation. We are asking ourselves how energy consumption and CO2 emissions can be reduced by the simplest possible means. This does not always have to involve extensive insulation of the building envelope – often insulating the ceiling of the top storey and replacing the heating technology also increases energy efficiency. In principle, we do not rule out additional insulation. However, in our research project, we are investigating where it is particularly cost-effective, yet also energy-efficient.

An important project objective of “Einfach (um)bauen” is that energy savings should not just be achieved on paper, but also in reality. Refurbishments often result in rebound effects: After the refurbishment, residents heat their homes more, which means that some of the savings are wasted. We want to avoid this by precisely analysing user behaviour in the flats. It is helpful that “Münchner Wohnen”, Munich's largest municipal housing association, is on board as a project partner.

Your research has been focusing on prefabrication and modular construction for some time now. What potential do these methods offer to make construction sustainable – and sustainable construction more economical?

Jutta Albus: One major advantage is the saving of materials and resources, because the components are produced under controlled conditions at the factory instead of on the construction site. In addition, a lot of time can usually be saved because, for example, site preparation and prefabrication can run in parallel at the factory. And a shorter construction time is reflected in a higher return for the client.

In order to exploit ecological potential and keep emissions low, the factory and construction site should not be too far apart and transport distances should remain within reasonable limits. Another important question – for transport as well as for the utilisation of the rooms – is where to use room modules and where to use flat components. We are currently looking into this in our “Modular – circular – digital” research project. We are working with the companies Solid.Modulbau and Design-to-Production to develop a digital tool that automatically develops a building construction based on very simple principles – this can be a line drawing of a floor plan or a room program in the form of an Excel list. The program should determine independently which type of prefabrication and building materials are the most sustainable and efficient for which parts of the building.

Does prefabrication require architects to think and work differently in order to fully utilise its advantages, including its ecological benefits?

Jutta Albus: I think so. If I really want to achieve the potential of modular construction, I have to embrace the system concept. Many architects are rather sceptical about it – but I find it exciting to explore the limits of such a system and to test out the creative freedom it allows despite everything.