With one hand on the roof of a dark green car, the other grasping a fistful of green leafs from a local birch Per Bondemark, Product Manager for Prelaq colour coated products, demonstrates the secret behind the new Prelaq Energy colour coated steel sheet: “We use pigment with properties similar to pigments from nature in our new colour coated steel products and the effect is remarkable”, he says. “Our figures show that we can save up to 35 percent of the energy costs to cool a building when we replace traditional colour with thermal coating.”
This is a payback to nature, using the technique from nature itself. And the consequences could be just great.
“Up until now thermal coatings have only been used in the USA and in Australia”, Per Bondemark explains. “But the interest for the product is increasing as dramatically as the debate about the greenhouse effect is growing”.
In parts of the USA and in Australia air conditioning and other cooling devices demand increasing amounts of energy. Last year it was reported that parts of the electricity system for the entire USA were close to breaking down because it was overloaded when the summer temperatures rose higher than they usually do.
Today a government tax reduction is available when you use thermal coatings as roofing and cladding on buildings in the USA.
Of course, the areas referred to in this case have an average temperature higher than what we are used to in Europe, but the interest for thermal coatings is growing fast here as well. Recent summers have been extremely hot in countries around the Mediterranean Sea.
In countries in the south the thermal coating will reduce the energy used for cooling, but further north Prelaq Energy could be even more profitable.
Great savings
When the coating prevents temperature peaks inside a building, this can remove the need to invest in air conditioning equipment. An investment which often is in excess of 20 000 €.
This summer SSAB Swedish Steel have started a research project to investigate what Prelaq Energy really means by building four small houses at the rolling mill in Borlänge. Two houses have the thermal coating as roofing and cladding.
“In the very same houses we are doing tests with another kind of thermal cladding inside the buildings”, says Harald Svedung, R&D at SSAB Swedish Steel specializing in surface coatings. “In this case it is not only to keep the heat out, but also to keep it inside. You could say that the inside of the plate is smart, reflecting the heat from the sun during summertime and from sources inside the building in the winter. That is a more important aim in cold countries such as Sweden.”
Keeping warmth inside
The coating used contains a small amount of micro aluminium which reflects warmth from, for example, humans and machines used inside the building.
“You can feel it”, Harald Svedung says, and demonstrates by slowly moving his hand towards the wall.
It is obvious that the temperature rises the closer one gets.
“Still, measured by a thermometer the air temperature in the room has not changed, but when the infra waves are reflected to you it feels warmer. The experiment houses all have underfloor heating. When you turn your face towards the roof on a cold night you actually feel a heat mirror image of the heated floor, not a heat absorbing and cold surface. Thanks to Prelaq Energy in the roof you can save energy and still feel very comfortable.”
Prelaq Energy Interior is expected to save 5-8 per cent of the energy used for heating. Harald Svedung and Per Bondemark will be able to give more specifics after this winter when they can evaluate the figures from the test houses.
By combining the exterior and interior thermal coatings it is possible to build offices, shopping centres, exhibition halls, storage centres and other kinds of premises, which will save more energy for each passing year.
Fast pay-off time
“The investment will pay for itself in a few years and it is more profitable as long as the building is in use”, says Per Bondemark.
Exactly how profitable depends on a lot of factors, but the four small houses at the SSAB plant will answer some of the questions regarding the efficiency of the thermal coating.
This is very important as it is quite a new concept which you can make a one-time investment in a system that will be profitable in the foreseeable future.
The thermal coatings are expected to have a very long lifespan without more maintenance than normal for colour coated steel.
Less maintenance
“In fact we think that the need of maintenance will be reduced as the elongation of the sheets is reduced when they do not get that hot”, states Per Bondemarkt. “We expect this to give the roofing and cladding significantly longer lifespan. This is very valuable in particular in warm countries.”
SSAB Swedish Steel will start marketing the thermal coatings to architects and real estate companies, as those groups are very interested in investments which will reduce energy consumption in buildings.
“This is pretty much the same as with the advanced high strength steel which SSAB manufactures,” says Per Bondemark. “All of our products give added value on all levels, but most of all to the final user.”
Text: HÅKAN JOHANSSON
Photo: ULF PALM