Hiarc reflect lowers façade surface temperature

Hiarc reflect lowers façade surface temperature

Mar 24, 2014  | Materials 

Hiarc reflect lowers façade surface temperature
(Photo by: Ruukki)

Hiarc reflect is Ruukki’s first functional façade coating. It reflects some of the sun’s heat radiation to keep the façade of a building cooler than would be the case using a conventional coating.

Façade coatings are under continuous attack. A surface is required to perform well despite UV radiation, rain, snow, frost, dust, sand, soot and mechanical strain. UV radiation alone places great demands on surfaces. 

Heat radiation accounts for almost half of the energy emitted by the sun and each colour pigment has its own natural ability to reflect this radiation. Dark colours are more difficult since they contain a lot of black pigment, which efficiently absorbs and retains the sun’s thermal energy. A standard dark-coloured steel surface can reach a temperature of up to 80-90°C in the sun. When the structures heat up, a lot of energy is required to cool the interior of a building.

In higher temperatures steel is subject to thermal expansion. The structures contract and expand and become strained.

Also less need for cooling

Ruukki has a long track record of organic coatings. “We set out to develop a new product to respond to the challenges posed by UV and heat radiation from the sun. When developing the new coating, we also took into account trends in the construction industry and the opinions of customers and product end-users,” says product development engineer Katri Kivihaka at Ruukki. 

The reflective property of the coating is a result of modifying the colour pigments in the topcoat. The pigment best reflecting the sun’s heat radiation has been chosen from each colour pigment. For example, the blue pigment best reflecting the sun’s thermal radiation has been chosen from the blue pigments. 

“Depending on the colour tone of the panel and weather conditions, a reflective coating can reduce the surface temperature by as much as 20°C.” This reduces the need to cool the building and moderates the thermal expansion of the steel panels caused by temperature fluctuation”, Kivihaka explains.

Ruukki developed the coating in close collaboration with paint manufacturers. Product development also sought to achieve good scratch resistance and the highest UV class.

Coating also suitable for profiled sheets

The coating is meant for outdoor use, but not just for thermally insulated buildings. The coating effectively reflects heat radiation also in profiled sheets. A steel façade, like other metal façades, is subject to thermal expansion. A reflective coating keeps a dark-coloured façade cooler, reduces the thermal expansion of steel and the ensuing distortion.

A reflective surface also allows the use of longer spans with dark-coloured wall elements. The optimum benefit of the coating is obtained in combination with an energy-efficient wall structure, such as Ruukki’s energy panels.

Good wear and UV radiation resistance mean the original gloss and colour of the façade coating do not fade during the passage of time and also the surface also remains clean. 

Via Ruukki
Image,video ©: Ruukki