Solarlux Comfort Facade Marcel Billow

Rethinking the double-skin façade of the future

by Marcel Bilow

The Co 2 mfort Façade was conceived with the idea of a passive building with active users. Essentially, the concept of a building acting like a sailboat, where the natural resources are the real fuel.

Figure 2. Facade concept © Solarlux

We were commissioned to develop a climate concept for the new subsidiary of Solarlux in the Netherlands with the goal of achieving a close interplay of the building, the façade, and the building services components. The Co 2 mfort Façade posed a challenge and a different way of approaching the design, a design that had up and front the user experience. Me and my office of Imagine Envelope were the façade consultants, working alongside the client/owner and producer of the façade itself, Solarlux.

In our case, we were already involved very early in the design process. The idea of creating a sailboat was presented, as opposed to a motor boat. In principle, everyone can drive a motor boat. You just have to learn how to read a map and then will arrive to your destination, but at the end of the trip you always have to pay for the fuel. On the other side you can also learn how to sail. It’s not that easy but if you know how to, you can use nature in your favour. Sometimes it means you have to wait a day or two, if there’s no wind. However, using properly nature and its forces to your advantage, you’ll get somewhere.

When presenting the idea, the client was really enthusiastic with the sailboat concept. That was defined from the very beginning.

Figure 3. Facade concept © Imagine Envelope

We then started to develop the façade concept and its aim. In this case the company was the owner, the user, and the investor. Not only that, it was also the main producer of the façade itself. At Solarlux, they build sliding doors, balustrades, and various components related to façade, which made the project a wonderful opportunity to experiment. They wanted their building to be their showcase, representing what they do best. So, it was not just about showing the different systems and products but also showing the possibilities offered with sliding and open-folding doors, and the maximum performance they can actually have.

Having everything at our disposal, we had the idea of the CO 2 mfort Façade. It consists of two layers: the inner space is closed by the thermally insulated SL65 folding glass door with a wooden frame while the transparent SL 25 XXL slide-and-turn system forms an uninsulated glass layer on the outer side. Using these two layers we were able to create the optimal settings between a double closed cavity façade, a single layer façade hybrid ventilation and an outer layer that works as a buffer. Within the different seasons you are either able to use for benefits of a double façade or get rid of the glass in the second layer during the midterm seasons. The versatility the concept offered stuck directly.

As the concept developed, the technical air handling installations initially proposed seemed unnecessary, shifting towards a manually controlled ventilated building. To have more certainty about the natural ventilation concept and making sure it would work, the client included Transsolar, a climate consultant. They made sure through simulations that the ventilation was enough, assuring a functional façade. They also helped with the mechanical devices and the concrete core activation strategy. Additionally, a heat pump was used both in summer and winter to help with the temperature regulation. It also incorporates PV panels in the atrium, which at the end produce enough energy to render it almost self-autonomous.

Outside temperature 0° C I Outer and inner façade closed I Intermittent ventilation I Optimal heat insulation I Use of solar energy gains Outside temperature 10° C I Outer façade closed I Inner façade opened I Use of solar energy gains I Working in a wintergarden Outside temperature 20° C I Outer façade opened I Inner façade opened I Working on a balcony I Enjoy nature Outside temperature 30° C I Outer façade opened I Inner façade closed I Intermittent ventilation I Overheating prevented

Figure 4. Different facade strategies depending upon the comfort requirements © Solarlux

As part of the user experience, we had to explain the clients and employees how to use the façade and its different configurations. We arrived two days later after the moving-in, and we came to the surprise that everyone in the building was unhappy. We then found out they hadn’t set the façade into the proper mode (it was in winter mode, in a sunny summer day) which in turn heated the building tremendously. But we changed the configuration and the change was almost immediate.

It was within two weeks that the team get acquainted with the façade system and they really embraced it. Actually, they even used the cross-ventilation principle, which had to be adapted to the office conditions, using lowered trolley-desks to prevent the paperwork from flying away. They even have a system to communicate and let the people know which window should be opened to let the air in, in a regulated manner. A monitoring system stating the average energy use, the temperature and humidity, also helped the building to become truly adaptable.

Now, if you ask me, this design would be highly unlikely to be applied in a larger scale. The CO 2 mfort Façade succeeds because all the variables aligned: the client was also the user and producer of the façade. It was also a low-rise building which connected spaces that made cross ventilation possible. However, in a larger building with different users, the same dynamic would not work as the connection is lost between the spaces, and the training on how to use the façade would have to be too extensive to be realistic.

Besides, if motorized systems were to be included, the complexity of the project would not only increase, but regulations would almost cancel the versatility of the system as any accident by misuse resides in the designer and not in the user.

For us, we knew our contribution was done when the climate simulations fitted the requirements and the conditions we wanted to achieve. It also has to do with the budget: for the façade we spent 40% more of the destined budget but at the same time we saved 80% on the installation costs. The staff are the sailors who are able to actively influence the room climate and temperature using the façade. With this project, the focus is put back on the individual: an active user in a passive building. ” “The building sets new sustainable development standards; in terms of ecology, economy, as well as from the human point of view. ”

Figure 5. Indoor comfort strategies © Solarlux

Figure 6. Opening day of the building © Solarlux

Marcel Bilow formed part of Imagine Group, a network of builders, structural planners and climate designers, working on conceptual and experimental solutions for structural and climate-related challenges. He studied architecture in Detmold at the University of Applied sciences in Detmold Germany and finished with honours in 2004. Since 2006 he joined the Façade Research Group at the TU Delft. Marcel is known as a collector of skills, author of several books and head of the Bucky Lab in which he teaches students to develop and build full scale prototypes. He was also awarded as teacher of the year 2014-2015 in the Faculty of Architecture at the TU Delft.