Skip to main content

Green Nanotechnology for the Indoor Environment

Final Report Summary - GRINDOOR (Green Nanotechnology for the Indoor Environment)

Stand-alone description of the project and its outcomes
The GRINDOOR Project developed new materials and technologies for achieving energy efficient and healthy indoor environments in buildings. Two of the four subprojects dealt with electrical and thermal control of the throughput of solar energy and visible light in windows and glass facades, and the other two subprojects regarded recording of air quality and the use of solar energy to purify indoor air. A common set of nanomaterials (transition metal oxides) were prepared and analyzed by a common pool of techniques and were investigated for the purposes mentioned above. The Project included four PhD students and a number of post docs and senior scientists. A large number of interesting results were obtained and were disseminated via international scientific journals, at international scientific conferences and via news channels geared towards the general public. Results of commercial interest were transferred to Industry.
Some of the main outcomes of the GRINDOOR Project are as follows:
• Materials for electrochromic windows and glass facades, which allow the optical transmittance to be tuned between widely separated extremes, were studied with particular consideration of lifetime assessment and of materials rejuvenation to accomplish superior lifetimes. Formulas for lifetime prediction were obtained and were reconciled with surface-chemical reactions. A genuine breakthrough was obtained with regard to materials rejuvenation, and it was shown that severely degraded electrochromic thin films could recover their initial properties by a judiciously chosen, though simple, electrical treatment. This is a new result which may turn out to be a key to successful implementation of energy efficient and environmentally benign electrochromic “smart windows”.
• Materials for thermochromic windows and glass facades, permitting the solar energy throughput to be lowered automatically as the temperature rises above a comfort temperature, were developed with particular emphasis on novel ways to prepare thermochromic coatings via techniques enabling facile large-area manufacturing. We also explored an entirely new phenomenon—thermochromic light scattering—and demonstrated that the measured data could be reconciled with theory. Electromagnetic noise was used for the first time in order to develop deep insights into the thermochromic phase transition in VO2 thin films.
• A number of metallic and semiconducting nanomaterials were explored for the recording of gaseous pollutants characteristic for indoor air. Excellent sensitivity was obtained for acetaldehyde and formaldehyde with materials that can be prepared by use of industrially viable technologies.
• Solar-energy-powered purification of indoor air was investigated and decisive steps were taken to show that this technique can be of practical interest. A fundamental understanding of the underlying chemical reactions was developed. A breakthrough was obtained with regard to highly efficient photo-catalysis, and it was demonstrated that carefully tuned coating technology could yield thin films whose surface structures were dominated by crystalline facets that are known to be most efficient for photo-catalysis. This opens avenues towards the use of fenestration technology to accomplish efficient purification of indoor air.