Professor Angélil, on Friday your department will present the basic principles of “Towards Zero-Emission Architecture” to experts in construction and architecture. This means that the professors are unanimously demanding a shift away from focusing on energy consumption and thick insulation as advocated by standards such as “Minergy”. Why should emissions become the new target parameter in architecture?
The building stock generates around half of today’s total energy expenditure and CO₂ emissions nationwide. With “Towards Zero-Emission Architecture” we are striving towards the ideal of the 1-ton-CO₂ society, as anchored in the ETH Zurich energy strategy. Everyone should reduce their annual per capita CO₂ emissions to one ton; the amount of energy they consume in doing so is not significant. There is no point in saving energy ad absurdum without taking total emissions into account at the same time. Contributions from all sides, including from architecture, are needed to realise the aims of the 1-ton-CO₂ society.

In the past many architects have deplored the stylistic constraint of sustainability standards. Doesn’t your initiative primarily strike a blow for greater design freedom?
Of course, because it is our fight-back against one-sided standards. The architect is in a straitjacket if all buildings must be wrapped up in an outer shell 50 centimetres thick. With thinner walls, based on more intelligent heat flows, we will regain greater freedom in design.

What does low-emission construction actually look like in practice?
With “Towards Zero-Emission”, we also need less material. I can give you an example: I am currently planning to build 60 apartments in Esslingen. A central cluster of ground probes 300 metres deep will be used to air-condition the entire residential development. We store surplus heat in the ground during the summer, and we re-use it for heating in winter. This means the building will produce a heat surplus and we no longer need any thick insulation. Thus we can reduce the wall thicknesses from 50 centimetres, as is usual for the “Minergy” standard, to 30 centimetres. As a result we save 340 square metres of area and 1000 cubic metres of materials across the entire housing development. The construction therefore already entails less grey energy due to transport and material production.

How does the more economical use of materials affect the design?
Optimised material flows call for a change in attitude, a new aesthetic form and a different way of handling materials. We are returning to the basic structure; architecture must go back to being more honest and more direct. As I understand it, this also involves doing without multiple layers; we do not need immaculate claddings and coverings everywhere. It is more important for each component to have multiple uses. A concrete slab can also be a heat store, while at the same time performing fire safety and acoustic functions in the building.

In addition to reduced material flows during the manufacturing and waste disposal processes, the strategy also envisages emission-free running of the building. Where is the energy for this supposed to come from?
There is more than enough emission-free energy, we just need to use it intelligently. For that we must properly understand the energy context of a building and tap into all the emission-free sources. The temperature of human excrement, for example, is approximately 37°C, but we only need 18°C for heating. So it would make good sense to utilise this waste heat – initial test installations for heat recovery are already in operation. The same is true for the heat constantly emitted by our body.

But you cannot heat a ten-storey commercial building with that alone.
No, but a surplus of solar energy is also available, and the technologies at our disposal today to use and store this are much better than those of 15 years ago. We also need an “orchestration of technical systems”. There must be better networking of heat pumps, ventilation and heating systems, and sensors distributed throughout the whole building must ensure that equipment only runs when it is really needed. Nowadays we have small decentralised systems instead of enormous ventilation systems in the basement. The ventilation in a room, for example, does not start up until a carbon dioxide sensor detects that someone has entered it.

That all sounds very high-tech.
No, high tech is used only where it makes sense. A simple sun-shade on the façade is preferable to an elaborate control system indoors. Above all, using ground probes to store heat in the earth and re-using it later via heat pumps requires good networking, not high-tech equipment.

Technical control systems and heat pumps need additional electricity. Although representatives from the world of politics and economics warn of an electricity shortfall, the strategy also expressly excludes nuclear energy as well as fossil energy sources. Why?
The problem of waste from nuclear fission is still unsolved. Waste is a pollutant emission. Atomic energy is therefore incompatible with emission-free architecture.

Don’t you see any contradiction in the fact that nuclear energy research is also taking place at ETH Zurich?
No, there is room for different opinions at our University.

Don’t the demands of “Towards Zero-Emission Architecture” stretch far beyond the expertise of an architect?
At ETH Zurich we always imagine architecture in an urban development context as well. Power structures, conflicts of interest, cash flows and the participation of the residents play a decisive role in this. In this respect, every new building is also a political statement. Thus the part played by “Towards Zero-Emission Architecture” clearly extends into the political and economic spheres as well.

To what extent is your initiative integrated in a larger international trend?
Our strategy is unique and “very Swiss”. Architecture at ETH Zurich, in contrast to many American universities, has never lost its relationship with practice. Our research and education are highly oriented towards practical considerations. Moreover, a university of applied sciences like ETH Zurich has a huge amount of technical expertise available in-house, which is necessary for sustainability in the construction field. The engineers collaborate closely with architects and town planners. It is also a fact that the discussions about sustainability are already much more advanced here in Switzerland than in other places.

This raises the question: even if politicians and architects here in Switzerland support “Towards Zero-Emission Architecture”, wouldn’t that be just a drop in the ocean from a global perspective?
Every year we bid farewell to around 250 students whose education doesn’t mention oil-fired heating systems at all. Many of these students subsequently move to other countries where they put our ideas into practice and integrate them into new contexts. This also creates an understanding of sustainable building in Latin America or Africa from the bottom up in the long term.

Towards Zero-Emission Architecture

In a position paper, the professors in the Department of Architecture unanimously call for a paradigm shift in architecture: away from saving energy and towards freedom from emissions. Zero-emission architecture relates to a building’s entire life cycle - from construction through operation to disposal. The basic principles are just as applicable to new buildings as they are to the redevelopment of the existing building stock. A heat storage system in the form of ground probes, solar technology and heat pumps is an important component in this. Considerable savings are possible compared to conventional building methods as a result of the significantly reduced use of materials and the utilisation of self-produced heat. A large part of the “Science City” campus is being built and redeveloped in accordance with the rules of “Towards Zero-Emission Architecture”. A new building for the Institute of Technology on the “Science City” campus and a new building in the “Future Cities Laboratory” in Singapore are also planned according to the same basic principles.