Air conditioning consumes a lot of energy. ChromoGenics develops energy-saving electrochromic solar protection, in the shape of a thin polymer foil between the windowpanes that adjusts its transparency dynamically. A low electrical voltage, which can be applied automatically or manually, changes the materials degree of shading.

Buildings account for nearly 40 percent of the total energy consumption in Europe and the US, and about a third of the global emissions of greenhouse gases. In a global perspective, more energy is used for cooling buildings than for heating them. Making heating and cooling more energy efficient is one of the measures that have the greatest potential to reduce climate impact.

”Energy efficiency is a EU priority. It will be a deciding factor in reaching the 2020 target of reducing greenhouse gas emissions by 20 percent. Our dynamic windows reduce the need for air conditioning by adapting to the sunlight and blocking the heat. Controllable heat- and light transmission for buildings is a very promising technology”, says Thomas Almesjö, CEO of ChromoGenics AB, Uppsala, Sweden.

Smart glass technology

Glass facades provide light and open settings but they also place high demands on how energy should be handled, with respect to the environment, comfort and sustainability. Dynamic glass provides access to daylight while screening out direct sunlight. Photo: T. Brorson.

”The unique patent portfolio is the result of many years of research at the Ångström Laboratory in Uppsala. We have a leading position in electrochromic materials. Electrochromic windows can reduce the need for cooling by 20 – 40 percent, by controlling heat and light transmission while maintaining daylight and full view to the outside world”, Thomas Almesjö says.

ChromoGenics’ energy-efficient dynamic glass technology is based on a phenomenon called electrochromism. When a low electrical voltage is applied, the material alters its optical properties and the degree of shading changes. A negative current alters it back, making the window transparent again. The Uppsala company is the first to achieve electrochromic properties in a flexible and light-weight polymer foil. The 0.4 mm thin plastic film is laminated between two glass panes, and regulates the amount of heat and light that is transmitted. The foil has a multilayer structure comprising several different materials. A number of complex processes are required to generate the desired properties.

”We have built up a strong IP portfolio covering the technology. The ConverLight™ product is poised for its commercial breakthrough in the construction industry. The foil technology gives architects, window manufacturers and construction companies unique possibilities. It is very advanced technology – we are literally putting atoms to work – but the product is easy to use and control”, Thomas says.

Commercial buildings first

”ConverLight™-foil is delivered on roll and can easily be incorporated in the manufacturing process of window producers. By coating the electrochromic layer first on plastic, which is then laminated into a glass construction – rather than coating the glass directly – we contribute with a product that is scalable, cost-effective and sustainable. This system also allows the users to customize their shading; for instance, a glass facade could be divided in sections to provide different shading at different parts of the building. The transparency can either be automatically regulated, or manually controlled from a computer, mobile phone or tablet. ConverLight™ also contributes towards the requirements of the LEED and BREEAM environmental certifications”.

”After having performed a number of pilot projects, we are currently focusing on commercial sales to real estate projects in Scandinavia. That is where we believe the potential to reduce energy consumption and climate impact is greatest. Beside building facades, windows and roofs, electrochromic technology will also be relevant in various other applications such as buses, cars, trains and other vehicles, and consumer products such as ski glasses and motorcycle helmets”, Thomas Almesjö says.

The article was published in June 2017.