Picture: CLOUD No. 7 GmbH


The lean way of insulating

Good building insulation has a lot to offer: It not only helps to save energy but also protects against fires. Silicon-based CALOSTAT® thermal insulation material from Evonik optimally combines both of these properties. It also scores points with its slim dimensions, which enable it to be used in many different ways.

Many homes are energy guzzlers. Houses and apartments currently account for 28 percent of all the energy consumed worldwide. But this is set to change in the European Union. The EU’s Energy Performance Buildings Directive of 2010 stipulates that all new structures have to be nearly zero-energy buildings, beginning in 2021. A zero-energy building has roof-mounted solar panels or other means of producing sufficient amounts of energy to meet the needs of its inhabitants.

To achieve this target, buildings must substantially reduce their demand for primary energyThe amount of energy that has to be generated from fossil fuels in order to supply the buildings with heat and electricity According to a study conducted by the German Environmental Agency, this measure could reduce Germany’s demand for primary energy by 80 percent compared to 2016. However, this can only be achieved under two conditions: The energy supply must come from renewable sources, and the buildings must be thoroughly insulated.

Keeping heat and cold out

The thermal conductivity of a material is of crucial importance for its effectiveness as insulation. The lower this value is, the better, because the less heat the material conducts, the more effectively it insulates a building. That’s why Evonik began early on to develop an insulation material that has minimal thermal conductivity. The developers achieved a breakthrough three years ago when they created CALOSTAT®, thermal insulation board that is made of silicon dioxide.


W/(m•K) is the thermal conductivity of CALOSTAT®. This value is much lower than that of conventional insulation materials.

The material’s unique combination of properties makes it possible to produce completely new, high-performance insulation systems that use natural resources efficiently and are very environmentally friendly. This fact was also recognized by the Products Innovation Institute in the USA, which has awarded CALOSTAT® its Cradle to Cradle Gold achievement certificate. The institute evaluated the potential impact of the raw materials and process chemicals on the environment and human health, the product’s reutilization capacity, the use of renewable energy and the responsible use of water during the production process, and the producer’s adherence to social standards. “We’re observing a growing demand for eco-certified products in the construction sector. Ever since CALOSTAT® was launched on the market three years ago, we’ve regularly received queries from builders and architects who want to use this sustainable outstanding insulation material,” says Frank Gmach, who is responsible at the Strategy and New Growth Business unit of Resource Efficiency for marketing CALOSTAT®.

Cool in summer

Because the material’s low thermal, a building insulated with CALOSTAT® is protected against cold in winter. During the summer months, by contrast, the insulation layer keeps heat outside so that the interior remains comfortably cool even in hot weather.

Because the thermal conductivity of CALOSTAT® is hardly affected by the temperature, it also provides protection against hot summer weather.

The strong insulation performance of course has a positive effect on energy consumption. The less heat moves outside, the less heating is needed. Electricity is saved in summer because air conditioners and fans are needed less often. If the electricity and heat come from fossil fuels, insulation made of CALOSTAT® actively protects the environment.

CALOSTAT® doesn’t burn or get moldy

But sustainability and efficiency are not the only properties that good insulation material has to offer. Safety and fire protection are just as important, or even more so. For example, insulation made of organic polymers can help fire to spread—the disastrous fire in a high-rise building in London in June 2017 showed what consequences choosing the wrong insulation material can have.

CALOSTAT®, by contrast, acts as a barrier that prevents fires from spreading. In Germany, CALOSTAT® is categorized as a Class A building material, which means it is non-flammable. This is due to the material’s mineral nature and small pores. So it’s no surprise that the raw material for the insulation board, a silicic acid, has been used for many years in ranges and ovens to insulate ceramic cooktops against cables and countertops.

That makes CALOSTAT® superior to conventional insulation materials in two ways. For one thing, it has less thermal conductivity than pearlite, mineral wool, and glass wool, for example. The result is better insulation performance. For another, by contrast to materials such as polystyrene, it is not flammable.

Evonik supplies insulation boards made of CALOSTAT® in thicknesses ranging from 20 to 50 millimeters. This material combines high insulation performance with excellent non-flammability and high compression strength.
The facing bricks are filled with CALOSTAT®.

CALOSTAT® can be used in a wide variety of ways: as core insulation in supporting outer walls, as interior insulation, and as an insulation layer in facades and concrete sandwich elements. It can also be easily combined with almost every type of construction material.

Granules for reactors

In the future, CALOSTAT® will also be offered as a granulate. It can then be used to fill hollow spaces in order to insulate reactors and hot water tanks, for example. The development team at Evonik is currently working hard to ensure that CALOSTAT® also meets the most stringent standards as a granulate.


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