Papers by Author: Russell Binions

Abstract: Theoretically thermochromic glazing has the potential to reduce energy consumption in buildings by allowing visible light for day lighting, reducing unwanted solar gain during the cooling season, while allowing useful solar gain in the heating season. In this study building simulation is used to predict the savings made by novel thermochromic glazing coatings compared to standard products, for locations with different climates. The results suggest that thermochromic glazing can have a significant energy saving effect compared to current approaches.

Abstract: Thermochromic glazing is a type of intelligent glazing; one where the properties of the glazing change according to some external stimulus. More particularly a thermochromic window is a device that changes its transmission and reflectance properties at a critical temperature (Tc). Atthis specific temperature the material undergoes a semi-conductor to metal transition. At temperatures lower than Tc the window lets all of the solar energy that hits it through. At emperatures above Tc the window reflects the infra-red portion of solar energy. In such a way thermochromic windows may help reduce air conditioning and heating costs leading to more energy efficient buildings. This review details the nature of the semi-conductor to metal transition and indicates how substitutional doping within a crystal lattice can be used to manipulate and fine tune the critical temperature. Also detailed is the underlying science and methodologies so far employed in the production of thermochromic thin films.

Abstract: A numerical model was developed which enables the calculation of the optical constants (refractive index, n and extinction coefficient, k) of thermochromic coatings based in undoped and doped vanadium dioxide thin coatings deposited on glass for use as an intelligent window - a window that can change the optical properties in response to the temperature. From experimental results it can be seen that the vanadium dioxide coating prepared by Atmospheric Chemical Vapour Deposition shows a switching efficiency of about 30% at 2500 nm. In the visible range the transmittance and the reflectance does not change with the temperature both for the undoped and Nb doped VO2. For the Nb doped vanadium dioxide coating the switching efficiency is about 20% at 2500 nm. From the numerical simulations a n=2.89 and k=1.33 above Tc and n=2.39 and k=0.52 below Tc (at wavelength of 2500 nm) were determined for the undoped vanadium dioxide coating. The Nb doped vanadium dioxide coating calculations results on n= 2.45 and k=1.56 above Tc and n=1.92 and k=0.88 below Tc.