We Europeans have become accustomed to seeing solar panels on the roofs of buildings . But there are many other man-made surfaces in our cities and towns that could be used for energy, including the surfaces of buildings.
“In Europe there is a similar amount of square meters of building surface available as roof space,” said Dr. Bart Erich from the Netherlands Organization for Applied Scientific Research. He runs a project called ENVISION, which investigates technologies for obtaining energy from building surfaces .
The project team estimates that there is about 60 billion square meters of building frontage area in Europe (premium real estate to achieve the European goal of an energy-neutral built environment by 2050).
The project’s companies and researchers set themselves the challenge of making the apartments energy positive, meaning that the buildings generate more energy than they use . The idea is to integrate four new technologies into the facades of buildings to collect heat or electricity.
One technology is photovoltaic windows that harvest electricity . They have characteristics similar to stripes on glass, making them suitable for stairs or windows where light is wanted to enter, but full transparency is not required.
Another approach uses a special paint that absorbs between 40% and 98% of sunlight , depending on the color. The 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 tested in a school gym in Almere, in the Netherlands, where it was used for heating the gym and for hot water.
There are also colored glass panels with heat harvesting technologies . These can be used to decorate the facades of buildings.
The fourth technology uses special ventilated windows to cool a building in summer . “The glass is transparent and picks up near-infrared radiation (from sunlight),” said Dr. Erich.
By moving air through channels within the glass, heat is removed. It cools down because, like a blind, the glass filters the energy from the sunlight. Often a good amount of light is reflected outside, contributing to warming cities and increasing the demand for air conditioning.
Smarter surfaces
Many of us view everyday surfaces as something that simply should be durable. Professor Cesare Sangiorgi, a materials engineer at the University of Bologna in Italy, believes that we should expect more from these surfaces and that we can create a new kind of urban environment with smarter surfaces . “We seek to create more livable urban spaces and surfaces,” said Professor Sangiorgi, who leads a project called SaferUp.
The project funds early career scientists to research how to improve the sidewalks and roads that we bike, drive and walk on. Most sidewalks do not contain technology and are similar to those that have been used for centuries , but European scientists want to revolutionize this situation.
In the UK, researchers at Lancaster University, including one from SaferUp, are creating smart roads by placing electromechanical devices on them. When pressed by traffic, they convert mechanical energy into electricity. Under normal traffic conditions, this could generate enough power along a 1-kilometer stretch to illuminate around 2,000 streetlights or energy sensors that monitor traffic volumes. Field tests are planned for 2021.
Meanwhile, scientists at the University of Perugia in Italy are building smart sensors in cement that can be placed on roads or bridges . “The small particles transform their resistance into electrical current when they are bent or deformed by the passage of a vehicle,” said Prof. Sangiorgi. This is known as the piezoelectric effect , which occurs when mechanical stress is exerted on certain materials, such as ceramics.
“Various electronic parts are needed, but the material itself could then detect the weight, the speed or the number of vehicles passing over it and report on the state of the material with which a bridge is built ,” Prof. Sangiorgi said. In the future, this information could be downloaded to the phone or laptop by a safety engineer during road or bridge inspections. This could prevent catastrophic failures, such as the collapse of the motorway bridge in Genoa (Italy) in April 2018, through better monitoring of the wear and tear of these structures.
Cold cities
Futuristic flooring is also being designed to better handle heat. Today, many cities experience higher temperatures during the summer than the surrounding countryside, as buildings and pavements release heat from sunlight at night .
This heat island effect causes more illness and death , especially during heat waves. Scientists at the University of Perugia are developing lighter colored surfaces that absorb much less heat than black asphalt. This takes advantage of phosphorescent materials, which can store and then emit light. Specialty materials glow blue or yellow even when mixed with concrete. The temperature of this shiny pavement is lower than that of normal urban surfaces.
The pavement glow lasts an hour or two after sunset as it releases energy from sunlight, says Dr. Anna Laura Pisello, a materials scientist at the University of Perugia in Italy. “This can save energy in street lighting ,” he said. Testing of the mixture on Italian sidewalks began last year on the Perugia University campus and is expected to be used in the city later this year.
The asphalt surface can reach a maximum of 70 ° C during summer heat waves. Heating causes it to bend and crack, increasing maintenance costs and shortening the life of the surface. In Germany, a SaferUp scientist is working with another team to develop a network of pipes embedded in pavements to remove heat. “The tubes can get energy from geothermal energy to heat the pavement when there is ice or get the groundwater to cool a pavement when it is too hot,” said Prof. Sangiorgi.
As for new facades, Dr. Erich said, these typically do not return money to owners, but stained glass panels, for example, should give a return on investment in 15 years . As with paving technologies, the first step is to build prototypes in the lab and then test and display them in the real world. In the near future, buildings will feature more energy-harvesting painted panel mockups and clear and colored glass to showcase future facades. Photovoltaic glass is being tested in a utility building in Austria, ventilated windows and panels in a Genoa University building, and colored heat collectors in apartments in the Netherlands.
In the near future, Europeans will walk on smarter pavements, with sensors and electronics inside. When they look up, they will be able to admire attractive building facades that are quietly gathering energy from the sunlight while cooling the cities around them.
Artículo original
This article was originally published in Horizon, the EU Research and Innovation Magazine
