Rudra Dhar, Smart Window Technologies: Electrochromics and Nanocellulose thin film Membranes and Devices(2016)SDRP Journal Of Nanotechnology & Material Science 1(1)
Strategies for incorporating energy-efficiency requirements into building standards have been implemented by governments in developed countries in order to introduce the concept of green nanotechnology. Substituting regular glass windows in residential/commercial buildings with smart windows is the objective. The smart window is to function as electric dimming glass that is to be built with innovative nanomaterial based membranes/ coatings. Currently, the regular windows are made of glass and curtains/blinds are used to block sun light; eliminating such elements is of importance due to its limited functionality. Though these curtains/blinds blocks UV and prevents sun light illumination inside the rooms, but there are additional issues such as health hazards (e.g. dust and germ collection especially in hospitals) relating to asthma problems, disposal/recycling issues, regular cost, and maintenance which are some of the possible glitches. The smart window is expected to block harmful UV light and provide controlled privacy while also eliminating the problems related to curtains/blinds. Electrochromic (EC) smart windows are already in use that varies the throughput of visible light by electrical voltage or by solar energy application and are able to provide energy efficiency and indoor comfort. These smart windows comprises of electrochromic materials such as LixWO2.89 and HxNiO2 as cathodic and anodic oxide films, respectively, and other complex polymers, which are complicated to create, expensive and some are hazardous in nature. Nanocellulose (achieved from wood/pulp product) is already being used in flexible electronics, so nanomaterial membrane based suspended particle device (SPD) technology for smart window is a probable alternative to EC devices, but still under research. This paper reviews, introduces and discusses the present situation of both (EC and SPD) options for the state-of-the-art smart windows and its applications while also provide ample references to current literature of particular relevance and thereby, hopefully, an easy entrance to the research field. Also the paper presents an outlook for an innovative technology for smart-windows with SPD-EC technology to work as dimming glass on voltage application while also induce the capability of solar applications in smart windows leading to green nanotechnology in buildings.