In the United States alone, approximately 6% of the electricity distributed is used for heating and cooling systems. Reducing energy consumption caused by these devices is an important target due to its environmental impact. Research into the use of sustainable materials is focusing on this area; an example is MIT in Boston, with their recent announcement of the launch of a new material developed in conjunction with a team from the University of Hong Kong.
It is a transparent film which looks quite similar to other plastic coatings. Its distinctive feature however is the presence of a microstructure inserted between two sheets of glass, whose shape can be modified according to variations in external temperature.
An innovative filter for solar rays
This new development in the field of sustainable materials was designed with the aim of creating a filter for solar rays suitable for heating internal areas of buildings. The microstructure in the film is composed of spherical elements with a diameter of 500 nanometres. Once a temperature of 32°C is reached, they change size, creating a translucency on the glass, similar to frosting. As soon as the temperature goes down, the microstructures return to their original state.
This system enables around 70% of the radiation which heats an environment to be blocked, thereby reducing the work of air conditioning systems, with obvious advantages regarding both costs and the environmental impact. The collaboration between MIT and the University of Hong Kong was not casual. The Chinese city has in fact declared its target of reducing energy consumption by at least 40% by the year 2025.
Film for smart windows: when will it be available?
There is so far no definite date for when this film for smart windows will be available on the market. Its development is still underway. The next phase will involve the insertion of new microstructures inside the film, with the aim of making it even more efficient.
The development of this type of sustainable materials represents a key starting point for the smart windows of the future, which will not just be simple windows for the purpose of separating the internal environment from the external one, but intelligent devices capable of modifying their own characteristics according to climatic conditions.
According to one of the experts leading the MIT and University of Hong Kong research, the smart windows currently available on the market do not guarantee sufficient efficiency in their reflection of heat from the sun’s rays. Furthermore, those which function according to electrochemistry may require large amounts of energy for their regulation.
Consequently, there is considerable potential for the use of sustainable materials and optic coatings which can offer various solutions during the manufacturing phase. For now, researchers at MIT and the University of Hong Kong have explored this by testing particles composed of poly (N-isopropylacrylamide) -2-amminoethilmetacrylate chloride. When the temperature is above 29° C, these particles reduce in size, going from 1.388 to 540 nm circa.
At the same time, a bundle of fibre strands is being developed, which allows the material to reflect light in a different way. Researchers working on the project have compared the mechanism to a fishing net in the water, with numerous fibres, each one of which can reflect a certain quantity of light.
According to the research team, if this new technique in the field of sustainable materials was used on all the windows of a building, it would reduce the costs of heating the internal areas by 10%.
Translated by Joanne Beckwith