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Mythbusting in sunny Barcelona

“Energy production from solar cells and solar collectors is key to a Zero-Energy Building,” says Giovanni Nurzia, R & D project manager and solar “mythbuster” at Hydro's laboratory for Zero-Energy Buildings in sunny Barcelona.

Nurzia explains that energy-efficient façades can reduce the annual energy consumption of office buildings to below 50 kilowatt hours per square meter. However, energy-producing technologies such as solar collectors and solar cells are crucial in creating Zero Energy Buildings.

In the Zero-Energy Building laboratory in Barcelona, Hydro Building Systems is testing and comparing the performance of various solar technologies. When the testing is completed, Hydro’s solar team will choose the best technologies to optimize performance in building-integrated photovoltaics (BIPV).

Max Radt, who leads the solar competence center in Barcelona, underlines the importance of having accurate and reliable data when communicating with customers. He says there is great interest in building-integrated solar technologies, but also a lot of myths to be “busted.”

“A while ago, people were walking around saying that solar shading can save up to 30 per cent of energy needed for cooling. We wanted to take a reality check, and after some weeks of testing in our laboratory we found out that a room with sun-shading consumes 43 per cent less energy than a room without sun-shading at two typical summer days,” says Radt.

The tests at Hydro’s ZEB-Lab are performed inside two identical rooms next to each other. The two rooms are placed inside another bigger room to ensure that the different technologies are tested under equal exterior conditions.

Semitransparent solar cell glass

For now, the solar team is carrying out benchmark testing, comparing different technologies. One of the technologies is a semitransparent glass with amorphous Silicon (a-Si). Nurzia explains how this new technology provides comfortable light into the room and while preserving the view out the window. Thoughthe window looks relatively dark at close range, the visibility increases from a distance.

“There are three main purposes with these solar glass solutions: first, to produce electricity, second, to protect the inside environment from the heat, and third, to let some light into the room,” says Nuzia.

He adds that although most of the standard solar cell modules still are more energy-efficient, the new solar glass solutions have aesthetic qualities, which are also important to many customers. 

Testing all aluminium solar collectors

In addition to building-integrated photovoltaic solutions, the solar mythbusters in Barcelona are also testing the performance of solar thermal collectors. Hydro’s Precision Tubing business has developed new types of all aluminium collectors that are installed at the test site in Barcelona. The expected advantages are better or equal efficiencies at much lower cost, compared to the current industry standard using copper as basic material for tubes.

“A four-square-meter large installation is sufficient to supply a family of four with hot water,” says Nurzia, adding that the energy in the hot water could also be used for heating and cooling of the building.

The test site in Barcelona is part of the Hydro Building Systems ZEB-Lab network with test facilities in Bellenberg, Germany, and a planned center in Doha, Qatar.

“The network of ZEB-labs is important in order to compare the performance of solar and building envelope technologies under different climatic conditions,” says Nurzia.

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