Gigon/Guyer/Inge Zimmermann
Series Swiss ArchitectsEpisode 4:
How do aesthetics and climate protection come together? What does the house of the future look like? In an interview, the Swiss architect Annette Gigon talks about the challenges of CO2-sensitive construction.
This content was published on July 29, 2023 – 11:00 am July 29, 2023 – 11:00 am
Petra Krimphove
The highly acclaimed Kirchner-MuseumExterner Link in Davos in 1992 was the first major project by Annette Gigon and her office partner Mike Guyer. The two had known each other since studying at the ETH Zurich and founded the joint architectural office Gigon/Guyer in 1989.
Exterior view of the Kirchner Museum in Davos, 1992. Competition 1989, 1st prize Christian Beutler/Keystone
Since then, in addition to notable museum buildings such as the Kunstmuseum AppenzellExternal linkthe extension of Josef Albers Museum in BottropExternal link and des Swiss Museum of TransportExternal link in Lucerne also with residential and office buildings like this Prime TowerExterner Link made a name for itself in Zurich.
In recent years, as a professor at the ETH Zurich, Annette Gigon has also increasingly devoted herself to questions of climate-friendly and energy-saving construction. Together with assistants, she therefore developed basics on the climate balance of building materials and the operation of buildings that were as easy to understand as possible.
In their office practice, Gigon/Guyer are increasingly using wood as a sustainable building material, as they recently won in the competition for School building in LucerneExternal link. And yet, says Gigon, concrete still has its justification.
Exterior view of the Museum Liner in Appenzell. Since opening in 1998, the Museum Liner has become an icon of new museum architecture. Regina Kuehne/Keystone
SWI swissinfo.ch: Internationally, 37% of greenhouse gases are caused by the building sector. After all, concrete alone is responsible for eight percent of global greenhouse gases.
Anette Gigon: And steel for another eight percent. The high percentage for the building sector includes not only the emissions from construction but also those from use, for example for heating, hot water and artificial lighting. The material consumption is enormous, and the trend is increasing. There is tremendous building activity going on around the world.
Could these gray emissions be reduced, for example by using other, more climate-friendly building materials?
Yes, but I would like to start by saying that I am fascinated by all materials and that I try to be impartial. In architecture, it depends on how you use them. Nor is there any use in demonizing reinforced concrete. It is used so frequently around the world because it is easy to use, resilient and efficient in terms of earthquake safety or for fire and noise protection.
And bricks also have to be fired in a very energy-intensive manner. So they are not a real alternative. As a renewable building material, wood is theoretically climate-neutral, but in practice you have to fell it, transport it, dry it and usually glue it.
After all, wood and other biogenic materials also have the advantage of keeping carbon removed from the environment, at least as long as the buildings exist. But we have to be aware that the forests do not sustainably produce enough wood for global construction to be completely converted to it.
Keystone
It sounds as if zero-emission construction is still a long way off. What about the CO2 emissions caused by the heating and operation of buildings?
After the oil crisis and the warnings from the Club of Rome, energy awareness grew. Then the houses started to be insulated. In the 1980s, when we studied, five centimeters of insulation was the standard, today it is four to six times as much. Most of the buildings of the last three decades only need to be converted to heat pumps.
The older buildings, which are not yet insulated or only minimally insulated and are mostly still heated with fossil fuels, cause more concern. It is about half of the building stock in Switzerland. Many old buildings only became energy wasters with the introduction of central heating. Previously, only individual rooms and these only temporarily were heated with stoves, but after the installation of central heating the whole house was heated around the clock.
So the biggest lever is the insulation?
We examined this in a study: if we provide a house with a 20 to 30 centimeter thick layer of insulation, install a heat pump, install photovoltaic elements and also include all gray CO2 emissions from the entire conversion including adding another storey, the CO2 emissions drop Operation plus amortization of embodied emissions to a quarter of today’s annual value with gas heating.
For the entire CO2 balance of the building sector, it makes sense to upgrade old buildings in terms of energy, provided that today’s increased requirements, building laws and standards allow this.
How do you calculate the total emissions of a building – those that are in the building material and process and those that arise during operation?
This is referred to as a life cycle analysis. There are tools that allow estimates to be made early on in the planning process. They are currently finding their way into architects’ offices. More precise programs are rare and are usually reserved for specialists.
Unfortunately, we architects rarely find out how much energy the buildings we plan actually consume during operation. Even if or precisely because user behavior plays a role here, this data would be revealing.
At ETH you teach the next generation of architects. Do you sense a growing sensitivity to the topic of climate protection?
Yes! We have committed ourselves to the uncomfortable “self-enlightenment” and nevertheless had a large influx in the semesters. We have compiled the many facts and figures, looked at the building sector, but also taken a side look at our consumption and our mobility.
How many greenhouse gases does the construction of one square meter of reinforced concrete wall or the heating of this uninsulated section of wall with natural gas cause in just one year? The same amount, around 70-80 kg CO2! Incidentally, consuming a kilogram of Brazilian beef too. And the emissions from one bitcoin transaction were equivalent to those from about five square meters of concrete wall. Hardly anyone knows the orders of magnitude.
The complex problem cannot be tackled with keywords and half-knowledge. It is now a question of many people from all sectors “literating” themselves when it comes to CO2, applying and passing on the knowledge in their areas, because it is about the entire range of emissions.
We are all spoiled by cheap, available fossil energy, but we can no longer continue as before. It is the task of all of us to look for solutions and to act with caution.
Extension Josef Albers Museum Quadrat Bottrop, 2022. Competition 2016, 1st prize Stefan Josef Mueller
They started with the 2011 opened Prime Towerexternal link built what was then the tallest building in Switzerland in Zurich. It has a glass facade. It’s not generally considered to be very energy efficient.
Yes, glazing generally performs worse than closed walls with thermal insulation, even if the Prime Tower has very good triple solar control insulating glass as a façade. The fact that it still achieves good energy values is due to its compactness, i.e. the favorable ratio of facade areas to floor areas of one to three, but also to the windows that can be opened, the integrated sun protection and the heat pump heating.
Would you still build like this today?
Today the regulations are even stricter. The partially glazed Andreas Turm in Zurich-Oerlikon is an example. If we were given the task of building an all-glass skyscraper again, we would probably approach it in a similar way Würth Haus RorschachExternal link or that House Lagerstrasse in ZurichExternal link. Its façade consists of two layers of glass, one insulating and one shading. They are separated by a ventilated cavity in which the air flows around the sun protection.
Würth House Rorschach, Rorschach, 2013. Competition 2009, 1st prize Thomas Staub/Würth
In fact, in the competition design for the Prime Tower, we initially proposed a two-layer glass facade with external sun protection in between. For reasons of logistics and maintenance, the client later decided in favor of the realised, high-quality and compact construction.
What does the house of the future look like?
In the future, new buildings will be required not only to use energy very sparingly, but also to produce energy using photovoltaic modules. So far, however, it has remained a challenge in Switzerland to implement projects that also use the aesthetically unpopular elements on the facade. Winning competitions with it was almost impossible.
Im just finished Verkehrshaus LuzernExternal link For the first time we attached photovoltaic elements to the facade as a kind of jewel – the ambition was, together with the artist Urs Beat Roth, to develop a kind of ornament only through the proportions and the rhythm of their arrangement.
Swiss Museum of Transport – “House of Energy” multi-purpose building, Lucerne, 2023. (Visualization) Gigon/Guyer/Indievisual
How many design compromises does an architect have to make in the midst of growing regulations?
The increasing number of standards and specifications limit creative freedom – of course! We try to meet the new requirements, to implement them creatively and to elicit beauty from them.
The Kirchner Museum shows the insulating wood wool panels behind the etched glass facade. The insight into the construction is part of the architectural concept. We weighed down the roof with waste glass instead of gravel. It still glitters beautifully in the sun.
As builders, we have always tried to deal with the world, the environment, the materials, to elicit everything from them in order to create contemporary, exciting solutions. The transparent substance CO2, the revenant of everything we do, is what we are most concerned about right now.
In accordance with JTI standards
More: JTI certification from SWI swissinfo.ch