6.5 kWh/m²! The "Green Offices" project in Givisiez, Switzerland, breaks all records in terms of energy consumption..

Under the leadership of architect Conrad Lutz, the office building "Green Offices" was constructed in Freiburg's Givisiez, pioneering in the field of ecological construction. When choosing the interior cladding of the outer walls, the architect opted for FERMACELL fiber cement boards.

The office building, designed as an energy passive building, is certainly not ordinary in construction. The consistent use of natural and sustainable building materials ensures an optimal energy balance: Since the primary construction material is wood, energy consumption could be reduced to one-third compared to reinforced concrete buildings. In addition, the building, which exclusively used natural materials harmless to both humans and nature for its interior and exterior construction, meets ecological requirements certified by the "Eco" label.



Thanks to new technologies, the "Green Offices" building consumes only six percent of thermal energy and ten percent of drinking water consumption compared to comparable buildings with traditional construction technology. Every detail of this nearly square building is well thought out and "ecological," without compromising living comfort. Dry toilets reduce water consumption, heating is ecological using wooden pellets, large windows with triple glazing and individual shading options prevent rapid warming of the interior spaces. The optimal collaboration of natural building materials – wood, FERMACELL, clay bricks, etc. – ensures an excellent room climate. For these indicators, which set a new direction in sustainable construction, "Green Offices" received the label "Eco" as the first office building in Switzerland built according to the standards of an energy passive building. Architect Conrad Lutz was awarded the "Watt d'Or" prize for this project, which recognizes outstanding performances in energy efficiency by the Swiss Federal Office of Energy (BFE). The award is based on the idea of promoting future technologies and advocating energy innovations, and the "Watt d'Or" award serves in Switzerland as a quality seal for excellent energy products.

Conrad Lutz with the Watt d'Or award

According to architect Conrad Lutz, buildings should no longer be constructed any other way today. He mentioned this in an interview where he discussed his motivation to build efficiently, the challenges faced during the "Green Offices" project, and the innovative solutions that contributed to the success of this prestigious project.

Mr. Lutz, you have been building with consideration for the environment for over 30 years. What drives you?
Around 1973, during the first oil crisis, I began to take an interest in the topic of ecological buildings. At that time, I started to realize that buildings with better insulation contribute to reducing energy consumption. The focus was primarily on the idea of economy.

Today your project "Green Offices" breaks all records in terms of energy consumption...
Yes, the legal minimum for consumption today is 80 kWh/m², the low-energy (NED) standard is 38 kWh/m², and the latest limit has reached 25 kWh/m². However, this building uses only about 6.5 kWh/m²!

Therefore, "Green Offices" is also the first administrative building with the NED "Eco" designation. What prompted this ambitious project?
We wanted to provide evidence that it is possible to combine ecology and energy efficiency without it being expensive. This construction cost 20 percent less compared to traditional construction technology – thus, we demonstrated that there are no barriers to efficient building. On the contrary: today it should actually be built this way!

How did you achieve this goal?
The most important aspect is the combination of ideal building materials. That's why we primarily worked with materials from the wood processing industry, as wood has the smallest share of gray energy. In combination with intelligent building materials – such as FERMACELL – we achieved not only an optimal energy balance but also an excellent room climate. I have one of my offices in this building, and I can tell you: the climate here is excellent!

What are your experiences with FERMACELL materials?
FERMACELL has many proven advantages; we have been using it for over 20 years. This board, for instance, is thin and very strong – ideal for construction without vapor barriers. FERMACELL also works excellently in conjunction with other materials. In the "Green Offices," we could seamlessly use natural clay plaster, for example. Therefore, we will also be using FERMACELL for similar projects in the future.

We can congratulate you on the "Prix Watt d'Or" award. What does such recognition mean to you?
It is a nice acknowledgment and also an honor. It is slowly becoming evident that there is understanding in society for energy-efficient building technologies – even large investors are now considering very long-term strategies for their construction projects. We are pleased with this success and see that we are on the right path.