Because modern glass is so strong, people who live in contemporary glass houses can perhaps risk throwing stones. But modern glass is more than strong – it’s smart too. Smart windows change their absorbency as conditions change, permitting better control of brightness and temperature within buildings. The secret rests in coatings applied to the surface of the glass.
Low-emissivity glass reduces the amount of heat radiated from the windows. Low-e glass is coated with thin layers of certain metals and metal oxides. They let sunlight through the window, while preventing infrared radiation from escaping back through the glass. Low-e coatings absorb heat as it passes through the window and reflect it back inside. They are so efficient that double glazed windows act like triple glazed windows.
But there’s more good news! There are even self-cleaning glass coatings! Glass coated with a thin layer of titanium dioxide not only absorbs the energy from sunlight, but promotes chemical reactions that clean the window. This process works by breaking down organic dirt on a glass to form mainly carbon dioxide and water. This self-cleaning glass also discourages the formation of water droplets, so that water spreads out in a uniform film on the glass. In this way the surface continually cleans itself as it’s exposed to sunlight and rain.
So next time you look out of the window, remember the glass is doing more than giving you a view of the world.