Building façades and pavements in Dutch and Italian cities are being turned into smart, energy-harvesting surfaces and equipped with sensors to power, heat and cool spaces and even monitor roads.
Europeans have become used to seeing solar panels on the roofs of buildings. But there are plenty of other man-made surfaces in our cities and towns that could be used to harvest energy, including building surfaces.
‘In Europe there is a similar amount of square metres of building surfaces available as roof space,’ said Dr Bart Erich at the Netherlands Organisation for Applied Scientific Research. He leads a project called ENVISION, which investigates technologies to harvest energy from building surfaces.
The project team estimates that there are some 60 billion square metres of building façade surface in Europe - prime real estate for achieving Europe’s goal of an energy-neutral built environment in 2050.
Companies and researchers with the project set themselves the challenge of making apartments energy positive, which means that buildings generate more energy than they use. The idea is to integrate four new technologies into building façades to harvest heat or electricity.
One technology is photovoltaic windows which harvest electricity. They have stripe-like features in the glass, making them suitable for staircases or windows where you want light to come in, but complete transparency isn’t necessary.
Another approach uses special paint that absorbs 40%-98% of sunlight, depending on the colour. Painted panels are then attached to special heat pumps. ‘(These) can generate heat or hot water,’ said Dr Erich. The system also keeps the panels at a fairly stable temperature even during hot summer days, making it efficient at collecting heat. This technology has been trialed at a school gym hall in Almere, in the Netherlands, where it was used for heating the gym and for hot water.
There are also panels of coloured glass with heat harvesting technologies. These can be used decoratively on building façades.
The fourth technology makes use of special ventilated windows to cool down a building in the summer. ‘The glass is transparent and it harvests the near infrared radiation (from sunlight),’ said Dr Erich. By moving air through channels inside the glass the heat is removed. It cools because, like a window blind, the glass filters out energy from sunlight. Oftentimes, much light is reflected outside, contributing to the heating up of cities and boosting demand for air conditioning.
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