Project: New office building, Obere Waldplätze 12, Stuttgart, Germany
Construction firm: FKN Group
Customer product: e-coFACE, with CALOSTAT® Pure as insulating material
Builder: Drees & Sommer
Architect: SCD Architekten Ingenieure GmbH
Project duration: 07/2017 – 12/2021
The characteristics of the facade modules sound like they're straight out of a catalog of specifications for modern planners and architects: innovative, lean, high thermal insulation capacity, modular, recyclable, emission-free, non-combustible. But these – and more – are precisely the features of the facade of
the new office building that consulting, planning and project management firm Drees & Sommer is building for itself at its headquarters. While that combination may not yet be a given everywhere, the facade experts at FKN already have a finished product that can be mass-produced: e-coFACE.
Highly energy-efficient buildings are a key element of Germany's energy transition, and e-coFACE is leading the way in exterior insulation development. Apart from fire safety and sustainability, the most important issue for builders and investors is the insulation performance of the facade. The use of CALOSTAT® Pure as an insulator in combination with vacuum insulation panels (VIPs) lends facades outstanding insulation values and excellent fire protection while remaining very thin. The panel area of the facade that was developed has an insulation depth of 9 cm, with which it achieves a Ucw value of 0.4 to 0.5 W/m2K – a range corresponding to the insulating power of a traditional building exterior 40 – 50 cm thick made of masonry and mineral wool. FKN also has a comparable exterior panel with no VIP, which has already been given general approval as a qualified construction material (approval No. Z-23.11-2099).
That won over Thomas Berner, the OWP12 project manager for Drees & Sommer: “The e-coFACE facade gives builders up to 8 % more floor space in projects like these. When they compare the cost of the facade to the extra square footage you gain, investors immediately see the benefit they stand to gain when they sell or rent the property. The economics are extremely favorable.” Potential for the module with CALOSTAT® at ist core is substantial, especially in metropolitan areas, where space is scarce and expensive.
The overall design and planning of the new office space is remarkable too, however: the hybrid energy supply system combines geothermal and air-sourced heat pumps with solar panels on the roof and in the facade elements. Cradle-to-cradle concepts were brought to bear for all components, while premodularized components, digitally planned with LCM and BIM, enable an efficient design. Frank Gmach, marketing manager for Thermal Insulation at Creavis, Evonik's strategic innovation unit, made the following observation when visiting a construction site: “CALOSTAT®, a non-combustible, recyclable insulating material developed by Evonik, is a super-insulation material (SIM) as defined in Annex 65 of the Energy in Buildings and Communities program of the International Energy Agency. We make the product in Hanau and are poised to revolutionize the market.”
Like the core of a VIP, CALOSTAT® primarily consists of silicon dioxide, which, in the microporous form used, is a very poor conductor of heat – it insulates very well, in other words. The lambda design value of CALOSTAT® Pure is just 0.020. Although it does not absorb liquid water, the material allows water vapor to diffuse. It is also non-combustible (A2-s1, d0). As Gmach goes on to say, “In the e-coFACE facade element, this non-combustibility is what helps the VIP achieve the desired service life and plays a major role in fire safety. We're proud of the important contribution that CALOSTAT® makes in this one-of-a-kind project, which so forcefully demonstrates many technologies of the future.” The facade modules are prefabricated, making it easy for site workers to incorporate them into the building.
The facade modules are prefabricated, making it easy for site workers to incorporate them into the building.
Franz Ebert of FKN points out the slim design – just 90 mm of the actual facade.
During normal operations, the positive energy building generates more energy than it consumes.
Rendering: SCD Architekten Ingenieure GmbH
Because the insulation is so thin, it left room for easily integrating solar panels into the facade.
Photo: Drees & Sommer