| Summary: | 博士 === 國立臺灣科技大學 === 建築系 === 95 === Natural daylight including directional sunlight, diffused skylight and reflected light at least. Directional sunlight is difficult to apply to room lighting, because its illuminance value is too high to cause overheating and glare. Shading device installation generally relies primarily on shelter from directional sunlight, providing constant room-diffused skylight. The drawback of this method is that diffused skylight is almost insufficient in the core of a building, The climate of Taiwan is hot and humid in both summer and in autumn. The peak electric power load for the island also increases during this period. Maintaining a building during this period, when there are high levels of sunshine, requires high energy-consumption. Given this climate, it is natural to assume that outside shading devices should first be employed, if they can be applied to reduce the penetration of direct beams of sunlight through windows, and to promote an area of natural daylight, especially towards the back of rooms and opposite their windows. These measures in turn reduce building cooling load and electric power consumption. Applying the reflective qualities of a shading device to increase the depth of daylight penetration is important when attempting to improve both daylight level and quality in the deep areas of a room. Furthermore, the shading device saves energy by exploiting the bright daylight received during periods of intense heat, and thus can provide sufficient illuminance to a building.
The purpose of the research is to build a simple equation, for easily evaluating indoor illuminance applied in horizontal shading devices and light shelves design under clear sky conditions. Analyse and simplify from the basic natural daylighting theory such as Optical radiation method, Relative daylight factor and Global diffuse daylight availability model etc., and then derive the simple estimating equation of indoor illuminance under clear skies. Combine the advantage of experiment, it can relatively express the real daylighting situation while testing under clear skies, and analyse the data of experiment to revise this simple estimating method of indoor illuminance, so as to improve the accuracy and applications of the estimating method. And then propose that the most properly simple estimating method for lighting design to apply. This estimating equation and utilizing model can conduct more relevant researches in the future.
This article combines the advantages of daylighting calculations and physical models, in order to establish a simple way to estimate the indoor illuminance under clear sky conditions, which could be applied to the utilization of indoor daylighting of any building. Besides, under the none distorted condition, the hand calculated viewpoint of the application also contains the simplification, therefore we can use the popular Microsoft Excel software to carry on relevant calculation, which not only make the designer of the indoor daylighting to understand the natural lighting behaviour, master the changes of the tendency of any variable, but also energize the designing result to enhance the accuracy.
Through introducing the boundary condition and changeable factors to the above mentioned analysis, we may understand the illuminance of indoor daylight calculating model established by this research, which could help us to predict any lightening value changed by whichever variable, including Win, Alt, Az and Dep, even the shading style. So we are no longer restrained by the limitation set by the research model, so to compensate the module and data missed during the experiment, therefore time, space, human resources and the cost of experiment will be massively reduced and under the similar data material requested. Such simple, convenient estimation type with certain accuracy will enhance the promotion of the use of the facilities of natural lighting potency and energy saving, the beneficence of this effective tool would be invaluable.
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