Determination of Total External Illuminance on a Sloped Surface from Sunlight and Skylight

Abstract

Easy to use tables of external illuminance values for sloped surfaces can contribute to the ease of the design for buildings that contain skylights in a pitched roof. The number of skylights, area of the skylights, orientation of the skylights, etc. are more easily determined for the predetermined level of illumination required when the external illuminance on the skylights' surface is known. Equations such as the Moon-Spencer equation (overcast sky luminance distribution) and the Kittler equation (clear sky luminance distribution) are utilized in developing mathematical models for determining the exterior illuminance values.

Des tableaux d'emploi facile, de valeurs d'illuminance exterme pour surfaces en pente facilitent la conception d'immeubles avec lucarnes dans un toit en pente. Le nombre de lucarnes, leur surface, leur orientation, etc., sont plus faciles à définir pour la niveau requis d'illumination, établi au préalable, lorsque l'on connaît l'illuminance externe sur la surface des lucarnas. Dea équations tellès que celle de Moon-Spencer (distribution de luminance d'un ciel couvert) et celle de Kittler (distribution de luminance d'un ciel clair) sont utilisées dans le mise au point de modèles mathématiques pour la définition des valeurs d'illuminance extérieure.

Las tablas de valores de Iluminación externas fáciles de usar para superficies inclinadas pueden contribuir a felicitar el diseño de edificios que contienen tragalaces en un techo en declive. El número de tragaluces, el área de los tragaluces, la orientación de los tragaluces, etc. se determinan con mayor facilidad para un nivel predeterminado de iluminación requerido cuando la iluminación externa de la super*** je de los tragaluces es conocida. Se utilizan ecuaciones tales como la de Moon-Spencer (distribución de la iluminación de cielo nublado) la de Kiettler (distribución de la iluminación en un cielo despejado) para desarrollar modelos matemáticos para determinar los valores de iluminación exteriores.

Additional information

Notes on contributors

John Nettleton

A paper presented at the Annual IES Conference, August 8 through 12, 1982, Atlanta, Georgia. Authors: At the time the paper was presented, both authors were with the University of New Hampshire, Durham, New Hampshire. Mr. Nettleton is now with the United States Air Force.

Joseph Murdoch

A paper presented at the Annual IES Conference, August 8 through 12, 1982, Atlanta, Georgia. Authors: At the time the paper was presented, both authors were with the University of New Hampshire, Durham, New Hampshire. Mr. Nettleton is now with the United States Air Force.