Physicists at the University of Colorado Boulder have developed a new window insulation material that could dramatically cut energy loss from buildings without blocking the view outside.
The material is almost completely transparent, yet it insulates so well that it can stop heat from escaping through glass, one of the weakest points in most buildings.
The new material is called Mesoporous Optically Clear Heat Insulator, or MOCHI. It can be made as thin sheets or larger panels and placed on the inside of existing windows.
While it is still produced only in laboratories and not yet sold commercially, researchers say MOCHI is durable, clear, and surprisingly powerful.
“Windows need to let light through, but that makes them terrible at stopping heat,” said Ivan Smalyukh, a physics professor at CU Boulder and senior author of the study published in the journal Science.
“Finding insulation that is both transparent and effective has been extremely difficult.”
Buildings account for roughly 40 percent of global energy use.
A large share of that energy is lost through windows, which leak heat in winter and let it pour inside during summer. Smalyukh and his team designed MOCHI to slow that exchange, helping indoor spaces stay comfortable with less heating and cooling.
At first glance, MOCHI looks simple. It is a soft silicone-based gel, but its internal structure is what makes it special. The material is filled with a network of tiny air pockets, each far thinner than a human hair. These pores trap air so effectively that a sheet just five millimeters thick can block intense heat. In demonstrations, researchers showed that the material could hold back a flame without heating the surface on the other side.
More than 90 percent of MOCHI’s volume is air, but the air is organized with extreme precision. This sets it apart from aerogels, another type of high-performance insulation used in spacecraft and other advanced applications.
Aerogels also trap air, but their pores are arranged randomly, which scatters light and makes them appear cloudy. MOCHI’s pores are arranged in a more orderly way, allowing light to pass straight through. As a result, the material reflects only about 0.2 percent of incoming light, making it nearly invisible on a window.
The physics behind the insulation is simple. Heat normally travels through gases when energized molecules collide and pass energy along. Inside MOCHI’s tiny pores, those collisions can barely happen. The gas molecules hit the pore walls instead, which sharply limits heat transfer.
Beyond windows, the researchers see other possibilities. MOCHI could be used to trap solar heat for water heaters or building heating systems, even on days with limited sunshine. This could make renewable energy systems more efficient and affordable.
For now, MOCHI remains a laboratory invention. Producing it is slow and complex, though the ingredients themselves are relatively inexpensive. Smalyukh believes the process can be simplified for large-scale manufacturing.
If that happens, the future of energy-efficient buildings could look very different—and much clearer.
