To what does the title of your trilogy – “non nobis”, Latin for not we – refer?
This abbreviated quotation from the Latin author Cicero stands for the fact that we do not act for ourselves alone. What we decide and do as a society today reaches far beyond our own horizon and has an impact far into the future. What I want to do here is to show the interaction between what is happening in the world and the building industry.
You say that building influences global warming and vice versa. What do you mean by that?
Owing to climate change impacts such as heat and crop failures, certain regions of our planet will become uninhabitable in the foreseeable future; many millions of people will therefore begin to migrate. But then they will need to build a new home elsewhere – housing, clean water, schools, hospitals. How many billions of tons of building materials will be needed for this? What does that mean in turn for resource consumption, emissions and our
environment?
What is your main finding?
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 communicate it to the general public. Many people are simply not aware of the essential facts, which leads to wrong conclusions again and again. It was therefore important for me to create a general understanding, to define the terms clearly and to show the connections
Which inaccuracies and false conclusions did you come across in your research?
For example, the energy efficiency measures called for in the building industry always only refer to reducing energy consumption during the utilisation phase of the buildings. The question of how much energy is consumed to extract the raw materials required for construction, to process them and, finally, to assemble them into a building is simply ignored. Further, the fact that about 50 per cent of the emissions of a new building are caused before the actual utilisation phase is disregarded in the German government’s targets for the buildings sector. Nor has energy consumption during the deconstruction phase played a role so far.
What makes it so difficult to account for energy consumption during the construction of a building?
The energy consumption and emissions that are not directly related to the operation of the building are usually externalised, in other words, are not attributed to the buildings sector. For example, cement production falls under the industry sector, and transporting the cement to the concrete plant is recorded under mobility. Thus, a large part of the emissions caused by the building industry disappears into other sectors. In this way, effects are covered up – and the great leverage that architects and engineers have is undervalued.
You address the blurred distinction between energy efficiency and emissions.
I think it’s very problematic that there are calls, above all, for increasing energy efficiency and reducing the energy demand again and again. We don’t have an energy problem, we have an emissions problem. The sun radiates more than 10,000 times more energy onto the earth than we humans need. The problem is the climate-damaging emissions that result from combustion processes for providing energy, be they due to oil, coal, lignite, gas or wood.
How can architects build as emissions-free as possible?
We have to proceed more cautiously, in a more differentiated way. Architects must be aware of which building materials emit what (and how much). The second question concerns the distances over which the building materials are transported. If you drive precast concrete elements from Poland to Munich, the transport causes more emissions than the concrete itself. It gets even more insane when you obtain granite from China or marble from Italy. Even if it sounds romantic, we have to use local building materials. Building with clay also only makes sense if the clay does not have to be transported hundreds of kilometres on trucks. We always need to look at the whole picture.
What else is important besides the regional supply aspect?
The building industry is stuck in the dilemma of having to build more and at the same time accelerating processes that are harmful to the climate. The only chance is to get by with less material, to use lightweight construction techniques, to build walls and floors thinner again, even if that means they are less soundproof. We may also have to make concessions with regard to fire protection. These things alone can quickly reduce emissions by 20 to 30 per cent. We have to build in a way that encourages recycling, so we don’t have huge quantities of hazardous waste, instead valuable recycled materials.
Building with wood has been quite popular for some time. But you consider that as problematic as well.
I don’t want to condemn timber construction. But we are currently experiencing a situation in which the correlations are presented in an unclear way. Firstly, we don’t have enough wood to really do without other materials such as concrete on a large scale. Secondly, by cutting down a tree, we are depriving the forest of a part of its capacity to bind CO2. When the needles, leaves, twigs and roots of this tree decay, CO2 is released again. And a considerable part – we are talking about up to 50 per cent – of the trunk removed from the forest – in the form of production waste in the sawmills and woodprocessing plants – is incinerated to produce energy. This means that we find 50 per cent or more of the carbon contained in a felled tree back in the atmosphere as carbon dioxide in the relatively short-term. A tree seedling cannot compensate for these emissions by 2045 – that is the point in time from which Germany wants to be carbon neutral. For this to happen, a tree must live for more than 50 years.
Could public procurement legislation play a more important role in making construction more climate-friendly?
For me, public procurement legislation is a disaster. This has to do with the concept of legal certainty. Today, nothing is approved unless the public entity to which one submits an application or makes a request feels absolutely legally secure. This slows down quick action and thus innovation. Our society is chasing its own tail with its “fully comprehensive cover” mentality.
