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The Sandwich Solution: Lightweight Insulation for Building Renovation

Buildings are responsible for approx. 30 per cent of greenhouse gas emissions and 40 per cent of energy consumption in Germany. Increasing the energy efficiency of buildings is therefore a key element in the transformation of the energy system. According to dena (the German energy agency), 108 million tonnes of CO2 savings could be made per year in Germany through heat insulation. In order to achieve the climate protection targets, a large share of the building stock must therefore undergo energy-efficiency upgrades. The Innovation Department at Evonik in Marl has developed an efficient and slim insulation panel with a sandwich structure, which makes passive house standard achievable within short conversion times.

The sandwich-type panel consists of a Plexiglas® mineral lining on the outside and optionally on the inside too, the CALOSTAT® insulation material and a vacuum insulation layer. CALOSTAT® is an insulation material developed by Evonik specifically for the construction sector and is based on silicon dioxide. 

Engine for progress:

  • savings of 29 tonnes of CO2 per year at the pilot building
  • insulation and fire protection in one
  • ecologically harmless mineral oxide as a base material
  • 12-cm panel is sufficient for passive house standard
  • special pore structure allows for an even temperature in summer and winter
  • very easy installation reduces conversion times

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Photo: Evonik Resource Efficiency GmbH

The first reference property fitted with the sandwich panel is in Rheinfelden in Switzerland. The new cladding saves around 30 tonnes of CO2 per year.



Silicon dioxide is non-combustible and thus meets the high fire protection requirements that must also be considered in energy-efficiency upgrades. Because of this, it is also used in other products, for example as an insulating material in a low-temperature panel heating system (see gallery). With the surface made of Plexiglas®, the design and colour can be flexibly adapted and sound protection can be optimized. In comparison to conventional mineral insulating materials, with CALOSTAT® 50 per cent of the insulation thickness can be saved, so that a panel measuring only twelve centimetres in thickness is sufficient to achieve passive house standard.

Pilot building saves 29 tonnes of CO2

Within the context of a pilot project, an office and administration building was renovated in Rheinfelden in Switzerland. Taking into account the newly installed triple glazing, the energy saving is 200,000 kilowatt-hours per year (kWh/a). 143,000 kWh/a and 29 tonnes of CO2 are saved by the façade alone. The market launch was implemented upon presentation of the product at the "Bau2015" trade fair and completion of the reference property. A special advantage of this panel is the heat protection in summer. The material is very fine-grained, so there is almost no air movement in the pores. This in turn means that the insulation is virtually temperature-independent and the rooms stay evenly insulated both in winter and in summer.

Easy installation spares nerves and money

Easy installation reduces the construction time and spares the nerves of all parties involved. By reducing the renovation volume through maximum utilization of the existing elements and by maintaining the original building geometry, resources and the environment are also protected to a significant extent. For example, this means that a substructure that is old but still functions well and is matched to the insulation in terms of dimensions does not have to be modified. But it can also mean that in the case of consistently slim wall mounting, the roof edge does not necessarily have to be renovated; or that the outer area of the house up to the façade does not have to be modified, as a slim façade structure is retained after the renovation.

Recycling was already taken into consideration when the panel was being developed: The predominantly mechanically joined layers of various materials can be easily disassembled and correctly separated, which is an optimal prerequisite for recovery and re-use as well as for the recycling of building materials.


Photo: Evonik

“Innovative insulation systems based on Calostat® are very good examples of sustainable building renovation – a sandwich panel only 12 cm thick is enough to achieve passive house standard. As a mineral oxide, it is not harmful to the environment and, since it is particularly easy and, therefore, low-cost to install, it is economically attractive for both institutional and private builders.”

Prof. Ralf Schmoll, Corporate Innovation, Evonik Industries AG



Partners and sponsors


Partners:
  • Evonik Resource Efficiency GmbH
  • Evonik CREAVIS GmbH
  • FKN Fassaden GmbH & Co. KG