Clean Tech House

Brickworks at the forefront of sustainable construction

Article by Journalist Stener Glamann,

Published on Projectzero.dk on November 6, 2019

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Brickworks use enormous amounts of energy to burn clay, so how can such a company be anything other than a climate sinner?

The answer from project manager Jacob H. Bendtsen from Gråsten Teglværk is: Sustainable construction.

He shows around the almost completed demonstration house on Havnevej in Egernsund, close to the brickworks. The compact red brick building will be Denmark's densest house and the first detached house in Denmark to be certified according to the high DGNB standard, which is far stricter and more detailed than the Danish building regulations. Jacob Bendtsen himself is a trained DGNB consultant.

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Brick and insulation in one

The cornerstone of the sustainable house is Gråsten Teglværk's patented CleanTechBlock, which can double the company's turnover throughout Europe in just a few years. The product has been eight years in the making and was developed in collaboration with Aalborg University. The brickworks has received EU support for the process on several occasions, including to build and market the demonstration house.

CleanTechBlock is brick and insulation in one. A block consists of two pieces of brick with insulation material between them. The lightweight black insulation material is made from foamed recycled glass that has bound CO2, offering better insulation properties than atmospheric air.

Recycling and energy saving
This technique is also patented. The glass comes from recycling sites. They send the clean glass to glassworks, and then Gråsten Teglværk can remove the remains, which may well contain some plastic and porcelain. It is crushed into powder and later heated to 800 degrees under vacuum. Ordinary glass wool must be heated to 1,600 degrees, resulting in significant energy savings.​

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Cheaper and easier 
The finished product is approximately 10 per cent cheaper than traditional bricks and insulation material, and it is much easier to handle during the construction process. There is no mortar between the blocks; instead, a tile adhesive is used, so when the blocks are glued together, a finished, water- and heat-tight outer wall is created. It will last for at least 100 years, because there is no mortar to weather.

​​Before, during and after 

Durability is precisely the basic idea behind the entire DGNB certification. It is a points system built around 40 sustainability criteria. Here, the construction is assessed before, during and after.

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• Before – is the energy and resource consumption by the materials

• During – the construction process

• After – is energy consumption in operation, AND the need for maintenance and replacement

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An example that will surprise many is paint. It looks negative both before, during and after. In the demonstration house, Jacob Bendtsen has chosen raw brick walls made of recycled stone for the interior, which earns a high sustainability score. They do not need to be painted, and paint contains substances that are harmful to health.​

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Numerous examples

He has been involved in every detail of the construction, from design to material selection to heating, ventilation, and lighting. All materials are certified. The wood is made of Danish pine and birch, and an installation in the shower cabin recycles 80 per cent of the water. Additionally, there are no hanging lamps that require cleaning. These are just three of the numerous examples of sustainable solutions that interested parties can see and experience in the house on Havnevej in Egernsund.

Jacob Bendtsen emphasises that the many sustainable solutions have not made the house more expensive. He estimates that overall, it is 10 per cent cheaper to build according to DGNB, and this is adhered to in the demonstration house.

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Sustainable brick

Gråsten Teglværk would naturally like to sell brick and roof tiles, and Jacob Bendtsen is certain that these materials still have a future.

"Just think of the many churches and castles we have around the country. They have stood for hundreds of years because they are built of good material", smiles Jacob Bendtsen.

The innovation does not stop with CleanTechBlock. The next development project could involve recycled bricks.

Bricks consist of clay and sand. Sand is in glass and clay is in porcelain, so that we will continue with the recycling idea together with Sønderborg Forsyning, says Jacob Bendtsen.

At the same time, brick factories are working to reduce their energy consumption in the firing process. Gråsten Teglværk has reduced its energy consumption by 15 per cent in recent years and continues to develop along this path.