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Pr. Takashi Inoue

Department of Architecture, Faculty of Science and Technology, Tokyo University of Science, Japan


Talk Title
Energy Conservation of Buildings with Innovative Window Film

Talk Abstract

Radiation in the near-infrared range accounts for the largest component of solar radiation reaching the Earth’s surface, followed by visible and then ultraviolet range radiation. Focusing on the wavelength characteristics of solar radiation, we have developed and evaluated window systems that make use of special films and other technologies that were originally developed for large-screen TV displays and printing. The window systems reflect, refract, or transmit radiation of differing wavelengths in specific ways, for example, reflecting only near-infrared range radiation toward the sky in order to not only reduce the air-conditioning load of buildings but also avoid adverse thermal effects on the urban environment, or blocking near-infrared radiation while introducing visible light and directing it toward interior ceilings.

Glasses/films that utilize low-emissivity coating to reflect near-infrared components while letting in as much visible light as possible are already in widespread use. These films and glasses allow windows to serve their intended purpose—providing an outside view, creating a sense of openness, and letting in daylight—while also reducing the air-conditioning load caused by solar radiation and improving the indoor thermal environment. However, with conventional technologies, the near-infrared component of incoming solar radiation is simply reflected downward into the surrounding neighborhood, an inconvenient side effect that could significantly deteriorate the nearby urban thermal radiation environment.

Here, utilizing techniques originally developed to fabricate TV displays, we have conducted research and development of retro-reflective film that selectively reflects the near-infrared component upward while maintaining conventional levels of light and thermal performance. In experiments designed to examine the effect of glass façades with this film on the thermal radiation environment in front of the building, we indicated that with solar-shading Low-e double-glazing, mirror-like reflection of the near-infrared component led to large increases in sol-air-temperature (SAT). In contrast, with our technology, such increases would be suppressed. Specifically, measurements with a pyranometer and SAT-meter revealed that downward reflection could be markedly decreased by roughly 2/3, and horizontal SAT could be decreased by approximately 10°C. This retro-reflective film has been installed on the facade of a large building in Tokyo and its indoor and outdoor performance is currently being verified. By upwardly reflecting a portion of the solar radiation away from the city, the total heat input into the city is reduced, mitigating the heat island phenomenon.

Our laboratory is also active in the study and assessment of methods by which wavelength-selective refraction/reflection properties of daylighting films, plates and the like can be used to draw daylight into rooms while shielding them from thermal loading. In this way, effects conventionally targeted through architectural techniques could instead be obtained by the simple application of a state-of-the-art window film of only a few hundred micrometers in thickness.

It could be expected that such an approach would be readily applicable to existing buildings and contribute to the reduction of their overall environmental load.

Short Biography

Takashi Inoue is currently a Professor of department of architecture, faculty of science and technology at Tokyo University of Science, Japan. He graduates from the department of architecture in  the University of Tokyo in 1977, obtains degree of Doctor of Engineering from the University of Tokyo, and has over 35 years of experience in the research field of energy conservation concerning buildings and houses, particularly concerning building envelopes, such as development of high performance window system, combination control for solar-shading and daylighting. His works won many prizes, such as SHASE awards (both for Technology and Thesis), PLEA2000 Best paper award, Sustainable building award (by the Minister of Land, Infrastructure, Transport and Tourism), Environmental and equipment design awards, Japan lighting award, etc. He worked also as an expert reviewer of WG3 AR4 IPCC. He is last president of the Society of Heating, Air-conditioning and Sanitary Engineers of Japan (SHASEJ), which celebrated 100th anniversary in 2017.

Talk Keywords
Window Film, Solar-shading, Daylighting, Retro-reflective, Near-infrared range, Urban Environment.
Target Audience
Students, Post doctoral, Industry, Doctors and professors
Speaker-intro video

The International Conference on Innovative Applied Energy (IAPE’18)