|Title:||Daylighting performance assessment methods for high-rise residential buildings in a dense urban environment|
|Subject:||Hong Kong Polytechnic University -- Dissertations.|
Daylight -- Measurement.
Daylighting -- China -- Hong Kong.
High-rise apartment buildings -- Lighting -- China -- Hong Kong.
|Department:||Department of Building Services Engineering|
|Pages:||xxx, 323, 83 leaves : ill. (some col.) ; 30 cm.|
|Abstract:||The daylight provision in buildings is usually safeguarded by building regulations. A number of daylighting design and assessment methods are also recommended by the international standards, design guides and research reports. A review of published literature suggests that most of the building regulations and assessment methods are originally developed for low-rise building environment. They are either not suitable or difficult to be adopted in a dense urban environment like that in Hong Kong. Therefore, other methods have to be explored for buildings in a dense high-rise environment. This research study aims to develop daylighting design and assessment methods for high-rise residential buildings in a dense urban environment. The study uses Hong Kong as an example of a dense urban environment. The thesis presents methods for both general and detailed evaluation of daylighting performance. For most of the building designs, only a general assessment of the daylighting performance is required, especially at the early design stages. However, a detailed evaluation of the daylighting environment of a space provides useful information for the annual energy performance analysis, such as the energy saving potential for integrated daylighting and electrical lighting control. For general evaluation, the thesis discusses the use of several performance metrics: indoor average daylight factors for indoor daylighting, the external vertical daylight factor on windows for skylight availability to a room, and probable sunlight duration on windows as an indicator for sunshine availability. Calculation methods for indoor average daylight factors, vertical daylight factor on windows and probable sunlight duration were developed for buildings in a high-rise urban context. The calculations of average daylight factors and vertical daylight factor use the concept that the external view of the window is divided azimuthally into 36 segments, so that the exterior environment can be defined by 36 pairs of altitude angles describing the obstructions to daylight from the sky. As for the calculation of probable sunlight duration, a sky map of annual cumulative probable sunlight duration was constructed. The sky map presents the amount of probable sunlight from every portion of the sky hemisphere. A set of criteria for general daylighting performance assessment was developed using the data obtained from a questionnaire survey conducted in two residential building estates in Hong Kong. Two metrics are proposed for use in the detailed daylighting performance evaluation methods; they are the exterior vertical illuminance and the annual daylight exposure received at the external surface of a window. A year's profile of exterior vertical illuminance can be reorganized to evaluate the number of hours in a year for which the illuminance falls into the range of useful daylight. It provides a realistic measure of the true daylighting performance of a window. It also provides useful information for visual comfort and energy saving analysis. If the annual total daylight availability of a window has to be evaluated, the annual daylight exposure can be calculated. The methods of evaluation of these two performance metrics are elaborated in the thesis. As Hong Kong is one of the cities with very high building density, its regulatory control of daylighting in buildings is of great value to other urbanized areas. The performance-based approach, which is recently accepted as an alternative measure for regulatory control of daylighting in buildings, is reviewed in the thesis. It uses the vertical daylight factor at the centre of the window pane as the assessment parameter. The thesis discusses a new method called the orthographically projected area method which can be used for a fast evaluation of the vertical daylight factor at the window. The main contribution to knowledge of this work is the development of workable calculation methods for the evaluation of daylighting performance for residential buildings in a dense high-rise urban environment. These calculation methods offer clear procedures of daylighting performance assessment so that the building design for natural light can be optimized. The input parameters can be easily manipulated geometrically during the early design stages. The results of the study can help the building developers, architects, engineers, lighting designers, building environment assessors as well as legislators to set up an effective daylighting assessment scheme for high-rise buildings in a densely packed building environment.|
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