A new transparent material promises to greatly reduce heat loss through windows. The material can be applied to the inside of any window, is transparent and strongly counteracts heat transfer.
It is Mesoporous Optically Clear Heat Insulator (MOCHI), developed by a team at the University of Colorado Boulder. It is produced as a thin material that can be stuck on a window. The material has a long lifespan, according to the researchers.
"To block heat exchange, you can apply a lot of insulation material in your walls, but windows should be transparent," said Ivan Smalyukh, lead author of the study and professor of physics at CU Boulder. "Finding insulation materials that are transparent is really a big challenge."
Minuscule pores with air
MOCHI consists of a silicone gel, which has tiny pores significantly thinner than a human hair. These pores contain air, which blocks heat transfer. In this, it is so effective that a piece of MOCHI measuring just five millimetres is enough to hold a flame against the palm of your hand without burning yourself. The trick to this, according to Smalyukh, is precisely managing the pores with air.
The development is similar to aerogel, which is an insulating material that has been widely used for some time. Like MOCHI, aerogels hold air in small pores. With aerogels, however, these pores are randomly distributed throughout the material, so in many cases they reflect light rather than allow it to pass through. Consequently, these materials are usually not transparent.
Thin wires
MOCHI uses a liquid composed of surfactants, substances that lower the surface tension of a liquid. These molecules clump together to form thin threads, in a process similar to how oil and vinegar separate in, say, a dressing. The silicone molecules then adhere to these threads.
The researchers then replace molecular structures with air. This creates a material with a network of tiny channels filled with air. The researchers also compare MOCHI to bubble wrap.
'No chance of colliding freely'
The air bubbles in the MOCHI material are so small that the gas molecules in it can barely touch each other, greatly reducing heat transfer. According to Smalyukh, this gives the molecules no chance to collide freely with each other and exchange energy. Instead, they bounce against the walls of the pores. In the process, MOCHI reflects only 0.2% of the incident light.
A key goal of the researchers is to reduce energy consumption while increasing the comfort of homes. They point out that homes account for about 40 per cent of total energy consumption worldwide, but at the same time lose a lot of heat on cold days. With MOCHI, they aim to reduce heat loss and thus increase both the energy efficiency and comfort of homes.
The researchers share their findings in a publication in Science. It is unknown when we can expect to see the technology on the market.
