lasercut 1

Solar Energy Materials and Solar Cells 29 (1993) 1-26 North-Holland Solar Enerw Materials and So lar ell s erformance of laser cut light deflecting panels in daylighting applications Ian R. Edmonds School of Physics Queensland University of Technology P.O. Box 2434 Brisbane Q 4001 Australia Received 23 April 1992; in revised form 16 September 1992 The manufacture, application and performance of a material which combines light deflecting properties with good viewing transparency is described. The material, of similar thickness to conventional glass glazing, is produced by laminating laser cut acrylic sheet between sheets of glass. It is designed to replace glass in in clerestory windows and atria to improve the distribution of daylight in rooms. Equations for the deflection angle and amount of light deflected are derived and related to applications of the material for daylighting and for sunlight exclusion. Measured performance of the material in the daylighting application is obtained, in model rooms, for a wide range of sky conditions. The material is most effective as a hung or tilted window in direct sunlight, however improvement in interior illumination with the window vertical and in overcast conditions is also significant. 1 Introduction In large modern buildings the distribution of adequate daylight into the interior is made difficult by the economies of modern design which lead to large horizontal working areas of small vertical dimension. Daylight flowing in a generally down- ward direction does not effectively penetrate such structures and most modern buildings rely almost entirely on electric lights for interior illumination. The advantages of daylight are that it is free is derived from an inexhaustible nonpolluting source and provides more pleasant illumination than electric light. Therefore the question arises as to whether daylight may be distributed more effectively into buildings. The technically complicated approach involving solar tracking mirrors and light pipes has been explored [1-4]; however the simpler approach of replacing all or part of existing windows with devices which redirect light into a more effective direction seems more economically attractive. Previously described optical elements which transmit and deflect light have been based on refraction in prismatic elements [5] refraction and total internal reflection in prismatic elements [6] reflection at metallic surfaces [7] and diffraction [8]. Prismatic glass is suitable for diffuse daylighting and has been used commercially for some time in the form of Correspondence to: I.R. Edmonds, School of Physics, Queensland University of Technology, P.O. Box 2434, Brisbane, Q 4001, Australia. 0927-0248/93/ 06.00 © 1993 - Elsevier Science Publishers B.V. All rights reserved

lasercut 1

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