Windows are one of the weakest points in a building’s energy profile. While great gains have been made over the last couple of decades, windows still have issues with allowing in heat when you don’t need it — or cutting it off when you do. The company RavenBrick has developed what could be considered a bit of a game changer in window technology — a glass that automatically changes tint according to its temperature using nanotechnology. The idea is simple enough: when it gets hot the windows darken to block incoming solar radiation, and when it is cold they are clear to allow the free heat in — all without electricity.
The windows use “an organic, nontoxic polymer which changes its molecular structure in response to temperature.” A thermochromic filter is placed in-between the panes of glass and it can be adjusted for different ambient temperatures. This mean that the windows can be configured for site-specific applications — the radiation control can be finely tuned for each side of a building and for different locations. The windows do not change tint on a gradient but rather change from transparent directly to semitransparent and back again.
While buildings are complex and many factors go into determining their energy consumption, the founders of RanvenBrick estimates that in the right application their windows can cut a building’s energy use by 30-40% each year. That adds up to a potential simple payback of six years for the product.
Not only do the windows save energy but they also reduce glare and discomfort for folks who sit near windows at work. Interior blinds may cut the light but they need to be adjusted and are not very good at reducing heat gain in the summer months. The windows can also reduce air conditioning energy costs as well as the size of a building’s HVAC equipment. The first application of the windows will be installed in December at the new National Renewable Energy Lab building in Golden Colorado, adding another tool for designers seeking to achieve high-performing, comfortable buildings.