Green Nanotechnology

Nanotechnology, in particular nanophotonics, is proving essential to achieving green outcomes of sustainability and renewable energy at the scales needed. Coatings, composites and polymeric structures used in windows, roof and wall coatings, energy storage, insulation and other components in energy efficient buildings will increasingly involve nanostructure, as will solar cells. Nanostructures have the potential to revolutionize thermoelectric power and may one day provide efficient refrigerant free cooling. Nanomaterials enable optimization of optical, opto-electrical and thermal responses to this urgent task. Optical harmonization of material responses to environmental energy flows involves (i) large changes in spectral response over limited wavelength bands (ii) tailoring to environmental dynamics. The latter includes engineering angle of incidence dependencies and switchable (or chromogenic) responses. Nanomaterials can be made at sufficient scale and low enough cost to be both economic and to have a high impact on a short time scale. Issues to be addressed include human safety and property changes induced during manufacture, handling and outdoor use. Unexpected bonuses have arisen in this work, for example the savings and environmental benefits of cool roofs extend beyond the more obvious benefit of reduced heat flows from the roof into the building.