A new self-powered ‘smart window’ technology has the potential to bring about substantial reductions in energy costs in buildings. However, obstacles to widespread commercial rollout remain.

Smart windows set to drive down energy consumption?
Solar technology specialist Professor Sun Xiaowei of Nanyang Technological University (NTU) in China recently announced that he and his team have developed a ‘smart window’. Basically, the environmentally-friendly window they have invented draws on electrochromic technology, which basically causes the windows to change colour in response to an electrical signal. Moreover, Professor Sun’s window functions as a transparent storage battery. In other words, the invention is a self-powered window that can change colour. Electrochromic windows currently in use already use very little power, but the NTU team’s invention has the potential to increase the environmental benefits of this approach.

Optimising energy consumption

As long ago as 2010, the US National Renewable Energy Laboratory (NREL) announced that if smart windows were installed throughout the United States that would reduce the country’s total electricity bill by 5%. Professor Sun Xiaowei’s window is likely to improve on this figure. His fine-tuned electrochromic system is able to adapt to prevailing weather conditions outside the building by changing the colour of the glass, which will reduce the need for heating/cooling and internal lighting. Not only does the University of Nanyang’s unique self-tinting window require no electricity from the grid to operate but it will simultaneously function as a rechargeable battery. The window’s stored energy can then be used for other purposes, e.g. lighting up low-power electronics such as a light emitting diode (LED). “Our new smart electrochromic window is bi-functional; it is also a transparent battery,” points out Prof Sun, explaining: “It charges up and turns blue when there is oxygen present in the electrolyte – in other words, it breathes.” 

Overcoming the cost barrier to larger-scale development

There is nevertheless a dark shadow falling across this environmental advance – the cost of installing smart windows, which is prohibitive and not conducive to widespread rollout of the technology at the present time. However, in 2013 a Californian startup, Heliotrope Technologies, announced that it had come up with its own ‘smart window’ solution which it claimed could be installed at a very low price. “Price remains one of the biggest hurdles for wider adoption of smart window technology,” underlined Heliotrope co-founder and COO Jason Holt, who is working to bring his smart affordable windows to market as soon as possible. Heliotrope’s commercial drive is underpinned by research work at the Laurence Berkeley National Laboratory. Meanwhile, as more and more ‘smart’ buildings are being constructed, these modern buildings appear to be facing obstacles other than purely budgetary issues.
By Guillaume Scifo