|Quantification of luminous comfort with dynamic daylight metrics for energy-efficient residential buildings
|Mak, Cheuk-ming (BSE)
|FCE Awards for Outstanding PhD Theses
Dwellings -- Lighting.
Light in architecture.
Buildings -- Energy conservation.
Hong Kong Polytechnic University -- Dissertations
|Department of Building Services Engineering
|xxi, 143 pages : color illustrations
|Light is a valuable resource. Not only it brings people brightness and affects human circadian physiology, but also it enhances people's productivity and satisfaction. Increased consciousness about satisfaction such as thermal comfort, acoustic comfort, as well as luminous comfort has attracted people's attention to their living conditions. As Hong Kong has the world's densest and largest number of high-rise residential buildings, the local government recommends daylighting green features (balconies, sunshades and reflectors) incorporated in building development to enhance the current luminous environment of residential units. Therefore, the objective of this thesis is to address the following three important issues/questions. 1. What are the factors that affect the residents' luminous comfort? 2. Can we study the luminous comfort using numerical simulation? 3. How to use luminous comfort to guide the energy-efficient daylighting design? The first part of this thesis concentrates on the luminous comfort itself. As there is still no agreement and no scientific term describing people's satisfaction with the luminous environment, the luminous comfort was defined first. A framework of luminous comfort with physical environment factors, psychological feeling factors and behavior factors was proposed based on the literature reviews. Questionnaire survey was then developed and conducted to investigate the effects of daylighting and human behavior patterns on subjective luminous comfort in both private and public housing units. The factors of luminous comfort was tested and obtained by several non-parametric tests. The effects of different green features on luminous comfort and the practical functions of the green features were also studied. The result may help both government and residents understand the current situation of residential luminous environment and arouse their awareness of luminous comfort.
The design for daylighting innovates continuously as there have been fruitful researches aiming to bring more light into the room and make it more comfortable. Therefore, it is necessary to predict the luminous comfort level with some metrics which can be easily obtained. Based on the questionnaire survey, the second part provides climate-based daylight modeling and simulation of 108 unit cases to quantify the luminous comfort. Considering the actual climate for the selected building site, dynamic daylighting performance metrics are also studied. The statistical analysis found these two metrics, uniformity and Ave. DA300 (Daylight Autonomy), could be complementary to each other and have significant correlations and indications for luminous comfort. The benchmarks of these two metrics were also studied which make it possible to predict residents' luminous comfort without the post-occupancy evaluation. Hong Kong is situated just south of the Tropic of Cancer and receives a lot of sunshine which could generate more lighting energy savings and bring solar heat gain at the same time. Many researchers focus on the total annual energy consumption with the balance of both lighting energy and cooling loads. The third part of this thesis appealed that the energy-efficient design should guarantee residents' luminous comfort level first. Based on the second part, two luminous comfort zones were proposed and the units with higher value of these two metrics, in comfort zone 2, have a great potential of energy saving by compromising daylighting performance. A new metric EDR (Energy Daylight Ratio) was also proposed to reflect the relations between daylighting performance and total energy performance. Case study was conducted to optimize the green features' design and validate the utilization of the metric. The result showed the luminous comfort metrics could guide and help optimize the facade and energy-efficient design at the early stage.
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