An analysis of daylighting performance for office buildings in Hong Kong

Daylighting has often been recognized as a useful source of energy savings and visual comforts in buildings. Occupants expect good daylight in their working spaces. The quality and quantity of natural light entering a building depend on both internal and external factors. In Hong Kong, commercial building accounts for the major building energy use and electric lighting is one of the major electricity-consuming items. This paper studies the daylighting performance and energy implications for office buildings. A total of 35 commercial buildings have been selected in the survey. Key building parameters affecting daylighting designs are presented. Two typical office blocks were further analysed based on a lighting simulation program. The daylighting performance was evaluated in terms of daylight factor, room depth and glare index. It has been found that the daylighting performance for office buildings is quite effective. About one-third of the office areas that are near the perimeter regions have an average daylight factor of 5%. For inner region of deep plan offices, some innovative daylighting systems such as light redirecting panels and light pipe could be used to improve the daylighting performance. In general, the office building envelop designs are conducive to effective daylighting and proper daylight linked lighting controls could save over 25% of the total electric lighting use.     

Evaluation of lighting performance in office buildings with daylighting controls

Lighting control integrated with daylighting is recognised as an important and useful strategy in energy-efficient building designs and operations. It is believed that proper daylighting schemes can help reduce the electrical demand and contribute to achieving environmentally sustainable building development. This paper presents field measurements on daylighting for a fully air-conditioned office building in Hong Kong. Electricity consumption by the fluorescent luminaires, indoor illuminance levels and the room parameters affecting daylighting designs were recorded and analysed. The measurements covered several cellular offices facing opposite orientations with and without daylighting controls. The findings suggest that daylighting schemes can result in substantial energy savings in air-conditioned office buildings in Hong Kong. Results are presented and the design implications are discussed.     

The impact of daylighting on peak electrical demand

A complete analysis of the cost-effectiveness of daylighting strategies should include the impact of daylighting on peak electrical demand as well as on energy consumption. We utilized an hour-by-hour building energy analysis program to study the thermal and daylighting impacts of fenestration on peak demand. Fenestration properties and lighting system characteristics were varied parametrically for office buildings in Madison WI and Lake Charles LA. Peak electrical demand was disaggregated by component and by zone, monthly patterns of peak demand were examined, and impacts of fenestration performance on chiller size were studied.The results suggest that for daylighted office buildings, the peak electrical demand results from a complex trade-off between cooling load due to fenestration parameters, lighting load reductions due to glazing and lighting system characteristics. Lowest peak demands generally occur with small to moderate size apertures. With daylighting, peak electrical demand is reduced by 10 to 20% for the building configuration studied (37% perimeter zone, 63% core zone). This work indicates that solar gain through fenestration must be effectively controlled in order to realize the potential of daylighting to significantly reduce peak electrical demand.     

东莞市大型公共建筑能耗调查分析

本文对东莞市辖区内包括非政府办公建筑、商场建筑、宾馆饭店建筑、综合商务建筑及其它建筑在内的140栋大型公共建筑进行了能耗调查和分析,得出了该市各类大型公共建筑能耗状况及其特点,为今后的能耗定额研究提供依据。     

贵州夏热冬冷地区自然采光对建筑能耗影响分析

以贵州夏热冬冷地区公共建筑为研究对象,分析建筑外窗在不同窗墙比、遮阳措施,以及玻璃可见光透射比的条件下,对自然采光及建筑年综合能耗的影响。提出自然采光节能率及自然采光相对节能率作为自然采光节能效果评价指标,并得到了自然采光对建筑能耗的影响关系。结果表明,自然采光节能率、自然采光相对节能率随窗墙比增大而增加。建议外窗设计时选用高透型玻璃,窗墙比范围为0.4~0.45。     

The impact of zoning regulations on thermal comfort in non-conditioned housing in hot,humid climates: findings from Dhaka,Bangladesh

In parts of the developing world where densities are high but the availability of air conditioning is limited, building massing and height regulations can influence interior comfort levels. Dhaka, Bangladesh, is characterized by high population densities, a lack of open spaces, and high poverty levels, combining to produce living conditions which are not only uncomfortable, but may lead to the spread of disease. A recent change in zoning regulations provides an opportunity to assess the success of building heights and setbacks in improving indoor thermal comfort conditions. We assess the impact on thermal comfort within Dhaka’s non-conditioned apartment buildings of four zoning schemes which differ in their specifications for setbacks, maximum buildable area, and building heights; but that maintains the current density. Computer simulation techniques model the buildings to test solar, daylight, and ventilation inside the central building to calculate resultant indoor temperature, mean radiant temperature, relative humidity and air velocity. Comparison between these values helps to determine which zoning schemes produce the most favorable thermal conditions. Findings suggest that zoning schemes that provide better solar protection and better natural ventilation are able to reduce indoor temperature and increase indoor air velocity over that provided by current zoning regulations. Recommendations for revising current zoning regulations are given along with general recommendations for how buildings in hot, humid climates can maximize passive cooling, encouraging energy savings and environmental sustainability.     

Current design guidelines’ streetscape improvement for visual perception and walkability: A case study of Sejong City,Republic of Korea

This study explores how recent design guidelines have focused on the visual variety of streetscapes making them more attractive. To date, this topic has been one of the most challenging parts of constructing walkable streets. We evaluated the streetscape features of Sejong City, recently constructed as Republic of Korea’s new capital city, and investigated their relationships with design guidelines. Consequently, we identified three principal reasons related to the design guidelines for the visual monotony in the street produced by the most up-to-date design guidelines compared with an ordinary street. First, the design guidelines cannot restrict the construction of large-scale buildings on the street, hindering visual changes caused by the zoning ordinance regulations because zoning regulations took priority when it comes to urban planning and regulatory governance. Second, design standards intending for a consistent street wall of buildings, which were used only in regard to the street enclosure standard, produced less spatial diversity and indistinct building bases, presenting weak vertical articulation. Third, applying the uniform standards for each building created repetitive architecture despite design standards for visual variety, such as recessed top floors, arcades, and retail uses for the ground floors facing a street.     

Glazing energy performance and design optimization with daylighting

This study systematically explores the influence of glazing systems on component loads and annual energy use in prototypical office buildings. The DOE-2.1B building energy simulation program, which contains an integrated daylighting model, is used to determine fenestration energy performance in diverse climates. The sensitivity of total energy use to orientation, window area, glazing properties (U-value, shading coefficient, visible transmittance), window management strategy, installed lighting power, and lighting control strategy are all described. We examine the conditions under which daylighting reduces net anual energy use as well as those conditions under which energy use may increase. Combinations of wall and fenestration properties that minimize net energy requirements as a function of climate and orientation are described.     

气候适应型绿色公共建筑环境性能优化设计策略研究

基于不同气候区几个典型绿色公共建筑的设计实践，结合部分建筑运行实测效果，对比、分析了气候适应型公共建筑在改善建筑环境性能（自然通风、自然采光等）并节约能耗的综合技术策略，研究如何与建筑空间平面设计相结合，进而总结、归纳了在建筑体型、空间平面设计与节能或环境性能提升技术融合与协同推进的工作流程及经验。     

马勒米邮局赫尔辛基，1986

马勒米邮局是一座小型公共建筑,位于阿拉马勒米商业广场的一个角上,旁边紧邻另外一座大楼。它将成为沿贝克莱提街布置的低层公共建筑与城市多功能活动中心和游泳池之间的联系纽带。     

编制《内蒙古公共建筑节能设计标准》的几个相关问题

在全国大力推行节能减排的形势下,《内蒙古公共建筑节能设计标准》(DBJ 03-27-2007)顺应建筑节能发展需求,经多方论证现已完善成稿并于2007年11月发布。在编制过程中,笔者主要负责建筑与建筑热工设计部分的编制工作,包括内蒙古公共建筑节能设计气候分区、外围护结构的构造设计、建筑外围护结构热工性能的权衡判断与计算以及外墙平均传热系数的简化计算,对这4个主要问题做了较为切合本地区实际情况的具体规定。     

Formulation

Recent developments in building technologies in the USA, Europe and Japan reflect the trend towards more intelligent and energy-efficient buildings. A variety of building products with automatic features are being developed, and electronic building systems and computerized building components are being manufactured. Virtually all buildings being built today are equipped with some degree of advanced technologies: for example, electronic control devices and communication systems, automated building facilities, and office automation facilities. This paper outlines the current status of intelligent building technologies. Key features are presented, and the architectural issues associated with the incorporation of the new technologies are discussed. Particular emphasis is given to examining technological advances in daylighting, electric lighting, and HVAC systems. Although these technologies are being incorporated in intelligent buildings throughout the world, specific examples in Japanese buildings are presented to illustrate their implementation in building design.     

Intelligent building technologies: a case of Japanese buildings

Recent developments in building technologies in the USA, Europe and Japan reflect the trend towards more intelligent and energy-efficient buildings. A variety of building products with automatic features are being developed, and electronic building systems and computerized building components are being manufactured. Virtually all buildings being built today are equipped with some degree of advanced technologies: for example, electronic control devices and communication systems, automated building facilities, and office automation facilities. This paper outlines the current status of intelligent building technologies. Key features are presented, and the architectural issues associated with the incorporation of the new technologies are discussed. Particular emphasis is given to examining technological advances in daylighting, electric lighting, and HVAC systems. Although these technologies are being incorporated in intelligent buildings throughout the world, specific examples in Japanese buildings are presented to illustrate their implementation in building design.     

A study of the daylighting performance and energy use in heavily obstructed residential buildings via computer simulation techniques

The quality and quantity of natural light entering a building depends on both internal and external factors. In Hong Kong, many buildings are high-rise blocks constructed close to each other and hence the external factor plays a significant role in daylighting designs. This paper studies the daylighting performance and energy use for residential flats facing large sky obstructions via computer simulations. Key building parameters affecting daylighting designs are presented. The daylighting performance for typical interior rooms was investigated in terms of illuminance level and daylight factor. The daylight levels of residential flats can be severely reduced by neighboring buildings and hence the externally reflected component would be the main source of natural light. The indoor daylight levels for kitchen and living/dining faced large neighboring building were found always less than the standard maintenance illuminance during daytime period. These imply that many residential flats in Hong Kong would have to rely on supplementary electric lighting.     

广深机场天然光环境营造方式的比较研究

天然光环境更有利于人体健康与视觉舒适,这促使机场等大空间建筑对于天然采光设计的重视程度逐渐提高。比较广州新白云机场、深圳宝安机场T3航站楼两个大型机场的采光设计方案及其实际采光效果,文章旨在提出机场等大空间公共建筑采光设计应注意的问题以及设计原则。通过理论分析、现场测量、使用后评价等方法,研究两者在天然采光设计方面的优劣。经调研对比后发现开敞式大空间建筑使用集中式带型天窗不利于在整个室内实现均匀的天然光环境,而使用分散式平天窗更有利于营造均匀的天然光环境。     

Estimation of lighting energy savings from daylighting

This paper refines and validates the predictions of a simplified analysis method for evaluating the potential of daylighting to save energy use associated with electrical lighting. Specifically, impacts on daylighting performance are investigated for several combinations of building geometry, window size, and glazing type for several US and international locations. The impact of both dimming and stepped daylighting controls and their settings are also investigated. Predictions from the simplified method are validated using measurements obtained from field-testing of a daylighting control system utilized to operate lighting fixture illuminating an office space.     

Effects of daylighting options on the energy performance of two existing passive commercial buildings

Results are presented from a study of south facing roof apertures on two buildings from the U.S. Department of Energy's Non-Residential Experimental Passive Buildings Program. This study is part of a broad effort to evaluate the energy, functional and economic performance of all twenty buildings in the program based on on-site observations and physical data. The work reported here supplemented the basic building data with illumination data from physical models and from the buildings themselves, and with additional observations and measurements. Energy analyses were performed in order to examine more comprehensively the daylighting systems incorporated into the buildings, especially as they relate to (a) interaction between heating, cooling and lighting requirements; (b) integration of the electric lighting and daylighting systems and (c) functional effectiveness and occupant interaction with the daylighting system.Results of this study provide quantitative information on the energy benefits of the daylighting systems as designed and used in the two buildings examined. The daylighting strategies are shown to provide substantial energy savings over similar non-daylit buildings. In both buildings, manual control of the electric lights is used; the evaluation demonstrates that in these buildings this proves to be an extremely effective strategy. Factors contributing to this result are discussed in terms of the observed behavior of the occupants and functional requirements of the buildings.     

Simplified daylighting energy savings for non-daylighting building energy simulation programs

The California Legislature mandated the California Energy Commission (CEC) to establish and periodically update energy efficiency standards for new buildings. To this end, a sensitivity analysis was conducted by the Standards Development Office of the California Energy Commission for nonresidential buildings. The purpose of this parametric analysis was to determine which variations in building parameters actually have significant energy impacts.A “generic” building model was developed and implemented in conducting this sensitivity analysis. The generic model was used as an analytical tool in modeling the energy impact of building parameter variations, as well as architectural and mechanical energy-saving measures on the energy use of each module. It is recognized that the level of significant energy impact is equivalent to, or bounded by the accuracy of the energy analysis tools in predicting energy usage in actual buildings. For the computer program used, DOE 2.1A this accuracy is within ±5%.Since DOE 2.1A and most of the other building energy simulation programs do not have daylighting algorithms, another calculation tool was used to determine daylight availability and lighting power reduction on an hour-by-hour basis for each orientation. This is accomplished with a daylight reduction factor (DRF).Quicklite, a simplified daylighting program, calculated footcandle (lux) levels based on outdoor ambient light levels, physical room dimensions and properties. To assess the impact of the Quicklite calculated footcandle (lux) levels on artificial lighting use, a control scheme was assumed, and a DRF was calculated based on annual sky conditions by climate zone.Once the DRF values are known for each orientation, the electric lighting schedule can be modified. A new profile number, representing the proportion of installed lighting switched on at that hour, replaced the daily lighting schedules when daylighting was utilized (09:00 – 17:00). To test this methodology, a sensitivity analysis was conducted between DOE 2.1A with Quicklite modifications and DOE 2.1B which has a daylighting preprocessor. The results displayed a 3.6% variation in total energy use.We conclude that daylighting calculations for design days using simplified programs can be used to approximate daylighting energy savings in building energy simulation programs that allow zoned lighting schedules but do not calculate daylight contributions.     

Smart glazing solutions to glare and solar gain: a ‘sick building’ case study

Holographic optical elements (HOE) can provide solar control by reflecting/redirecting the beam (direct) radiation incident on a window. This paper considers HOE applied for solar control in an office development at Southampton University, UK. In 2000, a new University campus was constructed through the renovation of existing Victorian school buildings coupled to modern, highly glazed office extensions. However, the combination of the low thermal mass of the extensions and the high level of glazing led to excessive office temperatures and occupant discomfort. Office users are requesting the installation of individual air conditioning units which would represent an unacceptable indicator of the building's design failings. Simulation of the office structure has been undertaken using transient thermal analysis to model possible solutions. Forced air convection, louver systems and façade changes such as electrochromic glazing are considered in addition to solar control holograms. The simulations highlight the need for the elimination of solar glare within offices and for some form of control of artificial lighting within the building. It is predicted that HOE can produce a comfortable working environment whilst maintaining daylighting and external views from the office: a combination of benefits which competing technologies such as blinds cannot provide.