Daylight Integration Research Articles

Daylight Models—Singapore Sky

The daylight factor approach, based the assumption of uniform sky luminance distribution, has served the purpose of daylighting design in buildings for a long time. With the availability of cheaper and abundant computing powers, it is now possible to make use of more sophisticated algorithms, which can make use of the graded distribution of luminance in the sky vault. The variation of luminance distribution in the sky vault is of particular interest in ascertaining the glare problem in the application of daylight in the tropics. The daylight data of horizontal and vertical illuminances and irradiances in Singapore were analyzed by Ullah [1,2]. The illuminance data were applied to predict the potential of energy conservation with the integration of daylight with the indoor artificial lights[3]. The study of daylight in Singapore continued with more detailed observations using the sky scanner, which divides typically the sky into 145 circular patches. The luminance value of every single patch is captured by a computer-controlled scanner fitted with a luminance meter; simultaneous solar irradiance is also recorded with a solarimeter. There is a built-in safety device in the scanner that closes the meter aperture, whenever the scanner directly points to the sun. Thus, the scanner data are meant for evaluating the diffuse luminance distribution in the sky vault. The scanner is being used to collect the data continuously from 1996 till now at National University of Singapore, except for some lapses for repairs and maintenance. In 1998, Lam et al4 made use of part of these data to evaluate six sky luminance prediction models as an effort to adopt a sky luminance models for Singapore. Kittler, Darula and Perez5 proposed a set of 15 sky models for the world-wide use. Sky patch luminance and horizontal diffuse illuminance models were formulated as functions of solar and sky patch geometry for the sky luminance and of solar geometry for the horizontal diffuse illuminance, both normalized as the ratios to the zenith luminance. While the basic morphology of the function was kept, various sky types were represented by assigning differing values to the constants used in the functions. These models were also evaluated by Tregenza6 with the data for Fukuoka (Japan), Garston (UK) and Sheffield (UK) and again with a limited amount of data for Singapore. This paper attempts to make a thorough evaluation of the 15 sky models proposed by Kittler etal5 by calculating the sky patch luminance and horizontal diffuse illuminane using their equations and comparing them against the sky scanned measured data in Singapore and to obtain the equations which fit the best of these data.

Cylindrical illuminance and its importance in integrating daylight with artificial light

The cylindrical illuminance provided by artificial lighting and daylight on the working plane are determined. This enables the role of daylight integration with artificial lighting to be evaluated. The integration was carried out for two cases: the first in which the total horizontal illuminance at a point equalled 554 lux and the second case in which the total cylindrical illuminance at the same point equalled 150 lux. The results show that the role of daylight is greater in the second case.

International Daylight Measurement Programme -- Singapore data III: Building energy savings through daylighting

Average-year data from measurements of daylight and solar radiation at a measuring station in Singapore are used to assess the potential for energy saving through the integration of daylight in the lighting systems of Singapore office buildings.

A comprehensive approach to the integration of daylight and electric light in buildings

Effective daylighting within an interior space depends to a large extent on the shape and size of the building. However, it is often impossible to illuminate a building exclusively by daylight. In this paper we review the past and present attitudes regarding optimal utilization of daylight in deep interiors. Such an optimal solution seems to be an integration of daylight and electric light. Various concepts of integration are examined, starting with permanent supplementary artificial lighting of interiors (PSALI), and a comprehensive list of types of integration is proposed. The preferred type for a specific design depends on activity pattern, visual requirements, location, climate, etc. Human requirements, energy saving, and cost-effectiveness are examined as determinants for optimal integration.

側窓採光の事務所照明における昼光と人工光の協調の要件

側窓採光の事務所照明における昼光と人工光の協調の要件