Transparent domed skylights: Optical model for predicting transmittance, absorptance and reflectance

Abstract

/npsi/ctrl?lang=en http://nparc.cisti-icist.nrc-cnrc.gc.ca/npsi/ctrl?lang=fr Access and use of this website and the material on it are subject to the Terms and Conditions set forth at http://nparc.cisti-icist.nrc-cnrc.gc.ca/npsi/jsp/nparc_cp.jsp?lang=en NRC Publications Archive Archives des publications du CNRCThis publication could be one of several versions: author's original, accepted manuscript or the publisher's version. / La version de cette publication peut être l'une des suivantes : la version prépublication de l'auteur, la version acceptée du manuscrit ou la version de l'éditeur. Research and Technology, 30, 3, pp. 111-118, 1998 Transparent domed skylights: optical model for predicting transmittance, absorptance and reflectance Laouadi, A.; Atif, M. R. International Journal of Lighting Transparent domed skylights: optical model for predicting transmittance, absorptance and reflectance Laouadi, A.; Atif, M.R.A version of this paper is published in / Une version de ce document se trouve dans : International Journal of Lighting Research and Technology, v. 30, no. 3, 1998, pp. ABSTRACTDaylighting and thermal loads are very important design issues for skylight design, especially in large spaces such as atria. However, the trade-off between daylighting and thermal performance of skylights has been difficult to solve, due to a lack of daylighting and thermal design tools. A mathematical model was developed to predict the visible/solar transmittance, absorptance and reflectance of multi-glazed domed skylights for both direct and diffuse radiation. The model is based on tracking the beam and diffuse radiation transmission through the dome surface. Since all building-energy simulation and fenestration-rating tools are limited to planar skylights, the model was translated into a simple method where domed skylights were substituted by optically equivalent planar skylights. The results showed that domed skylights yield slightly lower visible/solar transmittance at low sun zenith angles and substantially higher visible/solar transmittance at high sun zenith angles, or near the horizon than planar skylights having the same aperture. Absorptance of domed skylights is higher than that of planar skylights, particularly at high sun zenith angles, or near the horizon. The model was also compared to the IESNA transmittance calculation procedure for domed skylights and to the Wilkinson model.

Daylight Transport Systems for Buildings at High Latitudes

“…Since their position is fixed, they mostly rely on the permanent light conditions, such as sky illuminance, and occasional direct sunlight incident on a collector's entrance. With the exception of flat glass [16] or dome [17,18] that (1) transmits light almost without changing its direction, the light is (2) reflected on an anidolic concentrator or hyperbolic concentrator [19], (3) refracted by the prismatic film in CPC [20], (4) deflected by laser cut panels (LCP), or (5) absorbed by a fluorescent fiber solar concentrator (FFSC) or a luminescent solar collector (LSC). Some active solar collectors were also studied with a fixed position (passive collection) [21,21].…”

Models of optical characteristics of barrel-vault skylights: development, validation and application

“…Introducing the concept of the optically equivalent flat skylight that has the same aperture surface area and yields the same transmitted, absorbed and reflected flux as the barrel vault skylight, the equivalent optical characteristics of barrel vault skylights are expressed as follows 3,14 :…”

Prediction Model of Optical Characteristics for Barrel Vault Skylights

“…can be obtained in a similar manner. This ray-tracing technique was originally applied to predict the optical characteristics of domed skylights (Laouadi and Atif 1998.…”

“…Introducing the concept of the optically equivalent flat skylight that has the same aperture surface area and yields the same transmitted, absorbed and reflected fluxes as the barrel vault skylight, the equivalent optical characteristics of barrel vault skylights are expressed as follows (Laouadi and Atif 1998;:…”