Nanomaterials for healthier indoor environments

© GRINDOOR

Establishing more efficient control of the indoor environment can have beneficial impact on not just energy consumption but also on the health of the users. One EU-funded project that tackles both of these aspects is GRINDOOR, a three-year project running to June 2016.

GRINDOOR (Green Nanotechnology for the Indoor Environment) is concerned with the refinement of materials and development of devices for maintaining a better indoor environment. Central to this is the exploitation of new nanomaterials based on some transition metal oxides, especially the oxides of nickel, tungsten and titanium. By depositing these nanomaterials in thin layers, GRINDOOR aims to produce a range of products to better control the indoor environment.

It targets two aspects of the internal environment, namely light and air. Regarding light, the nanomaterial is applied in electrochromic coatings on ‘smart’ windows to regulate the inflow of visible light and solar energy. In addition to the electrochromic coating, or on its own, thermochromic coatings are applied to the windows to provide large temperature-dependent control of the inflow of infrared solar radiation. The properties of both the electrochromic and thermochromic coatings are controlled automatically, to compensate for changes in external conditions and in the requirements of the users.

Regarding air, oxide-based gas sensors are being developed to monitor the air quality, especially with regard to formaldehyde, and photocatalytic coatings are applied in order to clean the air using solar energy.

The project’s technical achievements have centred on developing the most effective ways to deposit the coatings to optimise their performance. Refinements in the orientation of the nanocrystals have produced positive results on the electrochromic properties. In addition, the project has revealed a new technique for bringing new life to degraded films made from tungsten oxide, by passing a small current through it. The degradation process was previously thought to be irreversible, and the technique discovered has the potential to be exploited in a wide range of applications. A paper on the subject has been published in Nature Materials.

GRINDOOR’s coordinator, Claes-Göran Granqvist, Senior Professor of solid state physics at the Department of Engineering Sciences, Solid State Physics, Uppsala University, believes that the project’s products will help to improve the healthiness of indoor environments as well as reducing energy consumption. He foresees that the technology will be able to reduce energy usage by about 10 % in a commercial building, although this figure depends to some degree on the specifics of the building. In addition, the automatic control of light and air quality will reduce the demand for air conditioning, and therefore reduce the prevalence of the so-called ‘sick building syndrome’ in workplaces.

‘This project will contribute to better indoor climate where people will feel better and work better,’ he says.

The nanotechnology and products refined and developed in GRINDOOR have considerable commercial potential. These products are currently on their way out to the market, and the start-up company already set up to produce them is expected to expand significantly in 2016. In particular, the nanotechnology has given rise to a foil material that is very light and can be used by any window manufacturer to produce laminated glass that incorporates the electrochromic properties. There is nothing comparable on the market, and Professor Granqvist expects this product to have a significant commercial impact.