Natural ventilation contributes to comfort, reduction of energy use for air conditioning and improving indoor air quality in high-rise high-density residential buildings. Measures to improve its performance should be of interest to the general public. Among factors that have an impact on natural ventilation performance of residential units, openings configuration is perhaps the most investigated. Much research work has been done on investigating the impact of different configuration parameters, but most previous studies are focused on only one impact parameter. In this study, computational fluid dynamics simulations are conducted for evaluating the combined impact of different configuration parameters so as to identify the configuration parameter that has the highest impact on natural ventilation performance of residential units. Statistical analysis of simulation results revealed that amongst the five studied parameters (i.e. ventilation mode, window type, orientation, window-to-wall ratio and living room area), natural ventilation performance, represented by mean age of air, is most affected by the ventilation mode adopted (i.e. cross or single-sided ventilation).

Thermal comfort and indoor air quality (IAQ) of educational buildings can affect students’ academic performance and well-being and are closely related to ventilation energy consumption. Demands of the indoor environmental quality within the classroom generally vary with the education levels and result in ventilation energy consumption accounting for a considerable proportion of the total energy use in bulk educational buildings. Its huge energy-saving potential is attracting worldwide attention from scholars and governments. Therefore, appropriate operation strategies of ventilation systems should be adopted to effectively reduce energy consumption without sacrificing thermal comfort and IAQ. However, the absence of relevant standards and guidelines for designing a quality classroom environment considering the special features of educational buildings remains an important research question. This study conducts a comprehensive review to determine research gaps and identify future directions for the interaction between thermal comfort, IAQ and ventilation energy consumption for educational buildings. The review results show that: (1) The thermal comfort prediction model should consider the influences of genders, ages and socioeconomic backgrounds; (2) The mixed-mode ventilation coupling the natural and mechanical approaches is preferred given its advantage of lower energy consumption and improved thermal comfort, but its control strategies need further exploration; (3) Optimizing passive design parameters of buildings (e.g., window to wall ratios, window orientations and sun shading installations) can significantly reduce the ventilation demands while maintaining indoor thermal comfort; (4) More studies are required for investigating thermal comfort in educational buildings during the heating period; and (5) IAQ of university buildings clearly requires further studies, especially on bacterial and fungal aerosol pollutants, for a more comprehensive assessment of the built environment.

a b s t r a c tFactors affecting a residential unit's price are always of interest to homebuyers and building developers, especially in a city like Hong Kong which is known for expensive housing. Literature review indicates that the governing factors can be categorized into architectural and environmental attributes. Among different methods commonly used for pricing, the hedonic price approach is viewed as the most suitable. However, the successful use of this method requires that homebuyers know and choose the attributes. Whilst choosing architectural attributes are not a problem for homebuyers, the same does not apply to environmental attributes. Previous studies by the authors have proposed some simple indicators for quantifying the environmental attributes. Based upon the developed performance indicators and the transaction records of two representative housing estates (Royal Ascot ¼ RA and City One Shatin ¼ COS), details of the properties, including transaction prices, architectural particulars and environmental characteristics were numerically transformed for the hedonic price analysis. The analysis results revealed that the willingness to pay (percentage of house price in parenthesis) for architectural and environmental attributes was HK$302.3/ft 2 (5.8%) and HK$886.8/ft 2 (28.2%), respectively, for RA and HK$1672.7/ ft 2 (31.9%) and HK$111.5/ft 2 (3.5%) for COS. It was found that elasticity of substitution (ES) of environmental attributes contributed 3.4e13.3% of the property price, compared to 0.6e5.5% for architectural attributes.

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a b s t r a c tView is a key factor that influences property price. Previous studies represent view either by simple pictorial description of a scene, or by rather sophisticated mathematical methods. Both hinder proper allocation of a premium for different view obstruction levels for high-rise high-density urban environments. View obstruction level and the applicable premium are useful information for stakeholders of the property market for making optimum decisions. Accordingly, there is a need to develop a simple parameter for assessing view obstruction level. While view is difficult to define, reference is made to law cases which often settle view disputes by the extent of daylight obstruction. Shading mask is typically used to assess availability of daylight outside a residential unit and hence is an ideal parameter for assessing view obstruction. Computation of shading mask values (SMK) is a very complex task that needs meticulous site surveys, 3D drafting skills, and computer simulations. They are too effort intensive for stakeholders. This paper summarizes the relevant considerations and the case studies conducted to establish the average angle of unobstructed sky (q) as a simple parameter to represent mean SMK for assessing view obstruction. Correlation analysis of mean SMK of 708 case study residential units determined by the detailed computer simulation method and the corresponding angle of unobstructed sky showed that the latter can be used to assess view obstruction adequately close to simulation predictions. Given average angle of unobstructed sky can easily be determined based on the geometrical primitives of a residential unit, this can enable future allocation of a premium for different view obstruction levels for stakeholders.