What role does the construction industry play in relation to climate change? And what prospects does this open up? Architect and engineer Werner Sobek explores these questions in his trilogy "non nobis – on building in the future". The first volume, "One must start from what is", was published in 2022, followed by volume 2, "The Boundary Conditions of the Future", in 2023. We spoke to Werner Sobek about his insights.
What does the title of your trilogy – „non nobis“, Latin for „not us“, refer to?
This abridged quote from the Latin author Cicero signifies that we do not act solely for ourselves. The decisions we make and the actions we take as a society today extend far beyond our own horizons and have a lasting impact well into the future. My aim is to highlight the interaction between what is happening in the world and the construction industry.
You say that construction influences global warming and vice versa. What do you mean by that?
Due to the effects of climate change, such as heat waves and crop failures, certain regions of our planet will no longer be habitable in the foreseeable future; as a result, many millions of people will begin to migrate. But then they’ll need a built home in a different location—housing, clean water, schools, and hospitals. How many billions of metric tons of building materials will we need for that? What does that, in turn, mean for resource consumption, emissions, and our environment?
What is your key insight?
If we continue to build the way we do today, it will be a disaster for the climate. I wanted to back up this insight with facts and convey it to the general public. Many people simply lack knowledge of the essential facts. This repeatedly leads to false conclusions. It was therefore important to me to foster general understanding, clearly define the terminology, and highlight the connections.
What inaccuracies and false conclusions did you encounter during your research?
For example, the energy efficiency measures required in the construction industry always refer only to reducing energy consumption during the operational phase of buildings. The question of how much energy is consumed to extract, process, and ultimately assemble the raw materials required for construction into a building remains unaddressed. Furthermore, the fact that approximately 50 percent of a new building’s emissions are generated before the actual operational phase is not taken into account in the federal government’s targets for the building sector. Nor has energy consumption during the demolition phase played a role to date.
What makes it so difficult to account for energy consumption during the construction phase of buildings?
Energy consumption and emissions not directly related to building operation are generally externalized—that is, not attributed to the building sector. For example, cement production falls under the industrial sector, while the transport of cement to the concrete plant is classified under mobility. A large portion of the emissions caused by construction thus disappears into other sectors. In this way, the effects are obscured—and the significant leverage that architects and engineers possess is downplayed.You address the blurred distinction between energy efficiency and emissions. I find it very problematic that there are repeated calls to focus primarily on increasing energy efficiency and reducing energy demand. We do not have an energy problem, but rather an emissions problem. The sun radiates over 10,000 times more energy onto Earth than we humans need. The problem is the climate-damaging emissions produced by combustion processes used to generate energy, whether from oil, hard coal, lignite, natural gas, or wood.
How can architects build with as few emissions as possible?
We need to take a more careful, nuanced approach. Architects must be aware of which building materials emit what (and how much). The second question is over what distances the building materials are transported. If you transport precast concrete elements from Poland to Munich, the transport itself causes more emissions than the concrete itself. It becomes even more absurd when you import granite from China or marble from Italy. Even if it sounds romantic, we need to use locally sourced building materials. Even building with clay only makes sense if the clay doesn’t first have to be transported hundreds of kilometers by truck. We always need to look at the big picture.
Besides sourcing materials regionally, what else is important?
The construction industry faces the dilemma of having to build more while simultaneously accelerating climate-damaging processes. The only solution is to use fewer materials, employ lightweight construction techniques, and build thinner walls and ceilings again—even if they’re less soundproof as a result. We may also have to make compromises when it comes to fire safety. These measures alone can quickly reduce emissions by 20 to 30 percent. We must build in a way that facilitates recycling so that, after demolition, we don’t end up with vast amounts of hazardous waste, but rather valuable recyclables.
Building with wood has been quite trendy for some time now. But you consider that problematic as well.
I don’t want to condemn wood construction. But we’re currently in a situation where the context is being misrepresented. First, we don’t have enough wood to truly do without other materials like concrete on a large scale. Second, by fälling a tree, we deprive the forest of part of its CO2 sequestration capacityä. As the needles, leaves, twigs, and roots of this tree decompose, CO2 is released again. And a significant portion—we’re talking up to 50 percent—of the trunk removed from the forest ends up in thermal recycling as production waste from sawmills and wood-processing plants. This means that 50 percent or more of the carbon contained in a felled tree re-enters the atmosphere as carbon dioxide relatively quickly. A tree sapling cannot offset these emissions by 2045—that is, by the time Germany aims to be greenhouse gas-neutral. For that to happen, a tree must live to be more than 50 years old.
Cöuld public procurement law play a größer role in promoting climate-friendly construction?
To me, public procurement law is an absolute disaster. This hängs with the concept of legal certainty. These days, nothing gets approved unless the public agency to which you submit an application or express a request feels absolutely certain of the legal certainty involved. This slows down rapid progress and, as a result, innovation. With its “comprehensive insurance” mentality, our society is shooting itself in the foot.
Interview: Kristina Simons
A longer version of this interview first appeared on competitionline.com
