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This paper studies the effects of densely packed high-rise residential settings on human perceptions of oppressiveness and annoyance induced by road traffic noise. Earlier studies have discovered that negative oppressive feeling would be developed when people on the streets were surrounded by high-rises at proximity. However, little has been understood about whether the spacing between tall buildings and the distance separating them from the viewers living in opposite high-rises affect their perceptions of oppressiveness and noise annoyance. This study aimed at developing multivariate models to predict the probability of evoking the feeling of oppressiveness when dwellers come across views restricted and obstructed by closing-in high-rises, and the response of noise annoyance in relation to the visual attributes associated with the oppressing environment. 46 cases were used for statistical analyses after the recruits were successfully administered in 2 stages of laboratory experiments where they were exposed to 12 scenarios through projected composite images and to 18 scenarios experienced in immersive virtual reality. The results showed that separation distance and building spacing were inversely related to perceived oppressiveness and noise annoyance. Further, the models revealed that participants implicitly were willing to trade off 4 m of spacing for extending 15 m of separation distance, and 60 m of separation distance for reducing 5 dB(A) in sound pressure level.

This study formulated a new index for evaluating both the air quality and wind comfort induced by building openings at the pedestrian level of street canyons. The air pollutant concentrations and wind velocities induced by building openings were predicted by a series of CFD simulations using ANSYS Fluent software based on standard k-ɛ model. The types of opening configurations investigated inside isolated and non-isolated canyons included separations, voids and permeable elements. It was found that openings with permeability values of 10% were adequate for improving the air quality and wind comfort conditions for pedestrians after considering the reduction in development floor areas. Openings were effective in improving the air quality in isolated canyons and different types of opening configurations were suggested for different street aspect ratios. On the contrary, openings were not always found effective for non-isolated canyons if there were pollutant sources in adjacent street canyons. As such, it would also be recommended introducing openings to adjacent canyons along with openings to the target canyons. The formulated index can help city planners and building designers to strike an optimal balance between air quality and wind comfort for pedestrians when designing and planning buildings inside urban streets and thus promoting urban environmental sustainability.

This study has successfully formulated artificial neural network models to predict thermal comfort evaluation in outdoor urban parks in Hong Kong, a sub-tropical city, for both summer and winter periods. The artificial neural network models embracing two-hidden layers outperformed other types of commonly adopted thermal comfort models. The model prediction performance was considerably improved by including perceptions of microclimate, perceptions of environmental features and personal traits as additional predictor variables. Sensitivity analysis determined that thermal sensation is the most important factor influencing thermal comfort evaluation in outdoor urban parks, followed by air temperature for both summer and winter. Solar radiation is another important factor immediately following air temperature for winter. In contrast, perceived density of trees and perceived number of water bodies in a park were found to be more important than solar radiation for summer. The findings arising from this study should provide valuable insights for formulating effective strategies for improving the thermal environment in urban parks in different seasons.

Eighty-five measurement campaigns were performed repeatedly to compare the concentration variation profiles along two intra-urban roads-one with open configuration and the other with street canyon effect. Fixed-effects panel data analysis was applied for formulating a model to express the PM(10) concentrations along intra-urban roads in terms of parameters like nearby central monitoring data, traffic counts and meteorological conditions with an objective to analyze the PM(10) concentration variation patterns along the two roads. Our findings reveal that traffic intensity and metrological conditions exert influence on concentration variation for both types of road configurations while wind velocity only affect the pollutants removal effectiveness of open road configuration. Further analysis unveils that the PM(10) concentration distribution profiles within a compact city environment are not always uniform and are dependent on the road configuration. Considerable PM(10) concentration differences were observed along the street canyon, and 70% of their variations are attributed to variations in their road aspect ratios. By contrast, no significant concentration difference is observed at open road configurations.

As the number and complexities of green building developments are mainly driven by market demands, understanding of end-user behaviors towards their development eventually should play a crucial role on determining their successes. However, very few studies have been attempted to explore end-user behaviors towards green building development. This study successfully applied discrete choice experiments to reveal whether residents with green experience will have different preference and willingness-to-pay values for enhancements on various aspects of environmental performance in green buildings. Generally, both green and conventional residents had strong preferences and were willing to pay more for improving various aspects of environmental performance in green residential developments. They are found to be willing to pay more for energy conservation, than indoor air quality improvement, noise level reduction, landscape area enlargement, or water conservation. No significant differences are found in the preferences between green and conventional residents for energy conservation, indoor air quality improvement, indoor noise reduction, or water conservation, However, green residents were found to be willing to pay significantly less than the conventional residents for enlarging the landscape area within a residential development, despite it was perceived by green residents as one of the major elements that differentiate a green from a conventional development.

The relationship between house price and location is very complicated. Traditional theory mainly emphasizes the relationship between the effects of accessibility to central locations on housing prices and ignores location-specific attributes of housing. Previous studies at best examine only one or a few environmental amenities. However, little has been done on a high-rise, densely populated living environment. This paper thus aims to investigate the “neighboring and environmental characteristics” of a residential property on its market value in such unique setting. It uses a more advanced approach—i.e. a hedonic model with spatial adjustments—and applies GIS techniques. The findings are mostly consistent with our hypotheses. The traveling time from the apartment to the central business district is negatively correlated with housing price. Households are also willing to pay more for apartments with sea view and better air. However, greenbelt is not a significant variable on housing price and noise level is even found to be positively correlated with the price. This unexpected finding may be explained by the uniquely dense living environment in Hong Kong where households are willing to sacrifice serenity for convenience. The current research is adequately sophisticated and has contributed to a better understanding of the important theoretical question of how much a household is willing to spend on various environmental and neighbourhood attributes of an apartment.

This paper reports a pioneering and quantitative approach being developed for assisting a large-scale high-rise residential building developer in Hong Kong in monitoring the competitiveness in the supply of fresh and flush water pumps to the building development projects. Integrated empirical pricing models based upon the hedonic price technique have been developed for the supply of both fresh and flush water pumps to the developer and the competitive sector. Our results revealed that the pricing levels charged to the developer were comparable to the competitive sector even though the quality standards of water pumps delivered were much lower. Upon close examination of the market structure, it was found that this was possibly due to the Limit Pricing Strategy being adopted by two leading suppliers in the developer's market as a result of relaxing the pre-qualification to standards below the industry norm. This finding should add to our understanding on the impact on the market competitiveness due to relaxation of pre-qualification requirements. Besides, measures of enhancing competitiveness in the supply market have also been discussed.

A voluntary indoor air quality certification scheme has been proposed in Hong Kong for assessing and evaluating the indoor air quality level in a variety of public places like offices, restaurants and pubs. The scheme intends to promote the public well being, however, its technical and financial practicality has led to serious discussions among the government officials, practitioners and premises owners. Accordingly, this study intends to develop a protocol for examining its financial viability by linking the appropriate dose-response and economic data with the results from indoor micro-environment models. The financial viability of the scheme is evaluated by examining the cost and benefit associated with compliance on the different prescribed indoor particulate (PM10) levels. According to our analysis, the indoor action level of 180 microg/m3 as 8-h mean (with the objective of protecting the health of general public) does not require office owners to improve beyond the base setting. Nevertheless, owners should consider altering the base settings in their air conditioning systems so as to secure more benefit on every dollar they spent. On the contrary, the 20 microg/m3 level as 8-h mean (with the objective of providing comfort) is not considered to be financially viable for office owners as they will incur financial loss on compliance. Subsequent sensitivity analysis indicates that the total net benefit derived have a great dependency on the value-of-life estimates used. If conservative health estimates are adopted, the optimum level determined to be beneficial to both owners and the society will be 55 microg/m3, which can be obtained by operating the air conditioning system with a ventilation rate of 10 l/s, primary filters of 80-85% efficiency and secondary filters efficiency of 60-65% arrestance. This information should be extremely valuable for government officials and policy makers in assessing the financial viability of the voluntary indoor assessment scheme.

This paper reports an innovative, scientific and yet practicable approach developed in assisting a large-scale high-rise residential building developer in Hong Kong for monitoring the competitiveness in the switchboard supply to her development projects. In this study, a pricing indicator was developed for monitoring whether the pricing levels charged to developer had attained a competitive level. Our results revealed that the pricing level charged to the developed was far from competitive, and the high cost was contributed by inadequate competitiveness in the switchboard supply as a result of the practice of including only a limited number of suppliers on the pre-qualification list. By relaxing the pre-qualification requirements, the pricing level dropped to a very competitive level after two additional suppliers being included on the list.

The growing importance of the maintenance industry renews the interest of both practioners and academia working in the maintenance field. In the past or even now, most of the maintenance work contractors are selected purely on basis of the lowest tender prices, even though they are required to be undergone the pre-qualification process. However, it is increasingly admitted that the practice of awarding tenders on a basis of low tender price eventually would lead to the ultimate quality problems. In consequence, there is a serious outcry in the public sector demanding a revolution in the current tender awarding system. Accordingly, this study intends to test how different managers actually choose maintenance contractors. This in turn would lead us to focus on the identification of the major selection attributes, and the trade-off weightings among attributes during the selection process. In this study, the identification and the trade-off weightings for different contractors selection attributes are revealed by conjoint analysis. Meanwhile, a Likert scale rating is also used to reveal whether there are disparities between the relative perceived importance and the relative weights in actual selection in the contractors selection attributes. Our results found that there are some consistencies in the relative perceived importance and the relative weights in actual contractor selection. On the other hand, our results also reveal that the contractors should put more effort in improving their company reputation in order to win the maintenance contracts.

A major strength of the voluntary building environmental assessment method is to encourage good environmental practice beyond the current industry practice. For a successful voluntary scheme, the credit scale must be attractive to investors and performance-based criteria should be used. However, most of the current schemes use a combination of prescriptive and performance-based criteria, and credits are allocated using subjective judgement, irrespective of cost and practical implications of attaining improved performances. This is pointed to the need to establish an incentive-crediting scheme, which is oriented towards performance-based scales having credits linked to cost and performance. In formulating the incentive-crediting scheme, the cost effectiveness of different energy-saving level in a base building is investigated under the premise that the investors would pursue a strategy in the most cost-effective manner. This paper presents a conceptual framework for policy makers to formulate an incentive-crediting scale for accrediting criteria within the greenhouse gas objectives of a building environmental assessment scheme in Hong Kong, aiming to attract participation of the profit-maximising investors. Establishment of an incentive-crediting scale starts from developing a carbon dioxide abatement curve for greenhouse gas emission. This is subsequently followed by dividing the maximum energy-saving potential into ten equal energy reduction intervals. The incentive-crediting scheme is formulated on a basis that proportionally more credits would be rewarded for diminishing investment return of consecutive reduction levels in a base building.

Moisture permeability of building materials is essential information to predicting moisture transfer in buildings. The conventional way of measuring the permeability of a material is the standard cup test method, which is very time consuming. The paper describes an investigation into the feasibility of using a surface air dew-point probe (SADP), which was first designed by Tsuchiya, to significantly shorten the measurement time. An analysis is presented to show the degree of accuracy required of the measurement of the moisture content changes of the air flowing through the SADP in order that accurate measurement of permeability can be achieved. The requirement, however, may not be achievable with the dew-point temperature sensors currently available. An experimental method for solving this problem is suggested, based on experience gained in trial experiments.

A series of bioaerosol measurements have been conducted at two typical offices in Hong Kong for both a 4-day and a weekly period. Both the investigated offices were installed with heating ventilation and air-conditioning (HVAC) systems coupling with air handling units and fan coil units. Measurements were performed starting from early morning by the Anderson N6 impactor. The primary objectives of these measurements were to determine the temporal concentration profile of bioaerosol inside office environments during office hours, and to determine the effects of air change rate on the concentration profile. The highest bacteria concentrations were recorded to be 2912 CFU/m3 at the early morning hours during the starting-up period of HVAC systems. The highest fungi concentrations were recorded to be 3852 CFU/m3 during the weekend mornings. The results of studies also revealed that the air change rate inside the office environment had less significant effects than filtration on airborne bioaerosols. The background fungi concentration was found to have strong correlation with the indoor relative humidity level provided that the relative humidity level could be maintained for a certain period of time. Of the sampled bacteria 80% were found to be gram positive, while the dominating genera of fungi was found to be Cladosporium and Penicillium.

This paper examines the key issues involved in evaluating cost and benefits of various accredited criteria of an environmental assessment scheme in Hong Kong. Economic benefit–cost ratios have been developed for various criteria to help the developers and designers to identify the economic impact and cost effectiveness of the accredited criteria. Results of this analysis reveal that the economic benefit–cost ratios vary among different credits, and 24 out of total 56 credits could provide potential economic benefit for the developers and designers. Accordingly, a decision strategy for prioritising the criteria selection has been developed for the developers and designers. Besides, the use of economic benefit–cost ratios for revising the weighting scale within the performance-specific criteria is discussed.

This study evaluated the effectiveness of different configurations for two building design elements, namely building permeability and setback, proposed for mitigating air pollutant exposure problems in isolated deep canyons by using an indirect exposure approach. The indirect approach predicted the exposures of three different population subgroups (i.e. pedestrians, shop vendors and residents) by multiplying the pollutant concentrations with the duration of exposure within a specific micro-environment. In this study, the pollutant concentrations for different configurations were predicted using a computational fluid dynamics model. The model was constructed based on the Reynolds-Averaged Navier-Stokes (RANS) equations with the standard k-e turbulence model. Fifty-one canyon configurations with aspect ratios of 2, 4, 6 and different building permeability values (ratio of building spacing to the building facade length) or different types of building setback (recess of a high building from the road) were examined. The findings indicated that personal exposures of shop vendors were extremely high if they were present inside a canyon without any setback or separation between buildings and when the prevailing wind was perpendicular to the canyon axis. Building separation and building setbacks were effective in reducing personal air exposures in canyons with perpendicular wind, although their effectiveness varied with different configurations. Increasing the permeability value from 0 to 10% significantly lowered the personal exposures on the different population subgroups. Likewise, the personal exposures could also be reduced by the introduction of building setbacks despite their effects being strongly influenced by the aspect ratio of a canyon. Equivalent findings were observed if the reduction in the total development floor area (the total floor area permitted to be developed within a particular site area) was also considered. These findings were employed to formulate a hierarchy decision making model to guide the planning of deep canyons in high density urban cities.

Environmental Management System (EMS) has been one of the important tools for sustainable construction for around two decades. However, many issues concerning sustainable development have not been properly addressed, and there is a need for the introduction of green specifications to advance green performance in construction through contract management. This paper defines green specifications, identifies the reasons for adopting green specifications and highlights the environmental issues that may not be addressed by solely adopting EMS. It also presents the results of a recent survey of practitioners concerning their opinions towards green specifications and possible impacts arising from their adoption. From the results of the survey, a framework for developing green specifications is deemed valuable for the cities striving for sustainability. Interestingly, the level of acceptable changes brought about by green specifications as perceived by different industry stakeholders is found to be unrelated to whether they were from organizations implementing EMS or not.

Annoyance has been identified as the most important psychological impact arisen from noise. Besides socioeconomic status, residing neighborhood characteristics such as greenery has been shown to be able to reduce noise annoyance. To study the effects of these potential annoyance modifiers, nine hundred and ninety-two responses were collected through face-to-face interviews via questionnaire surveys. Among them, six-hundred and eighty-eight responses were collected together with adequate dwelling information which enabled a more accurate prediction of home noise levels. All these data were analyzed using an ordered logit model. Results indicate that greenery perception exerts considerable influence on noise annoyance rated at home. Wetland parks and garden parks are shown to be able to reduce noise annoyance to a greater degree than grassy hills. And the effects of the perceived amount of greenery on noise annoyance reduction at home differ according to the setting of greenery to which participant perceived from individual home.

Green specifications constitute one of the important elements in green construction. New sustainability requirements and changing priorities in construction management have spurred the emerging green specifications to a faster pace of development. A cross-sectional survey has been conducted in Hong Kong in 2007 to identify principal factors leading to the success of preparing green specifications. Based on extensive construction management literature, 20 variables concerning sustainable construction were summarized. Using the Mann-Whitney U-test, the subtle differences between stakeholders in specifying construction work have been detected even with the high consistency of the responses among the groups. Moreover, five independent factors for successful specification of green construction have been categorized by factor analysis. They are related to (1) green technology and techniques, (2) reliability and quality of specification, (3) leadership and responsibility, (4) stakeholder involvement, and (5) guide and benchmarking systems. Whilst the first and fourth factors are generally more important, different stakeholder groups have different emphases. The results of the survey have been validated against established principles.

Unlike commercial premises, the indoor air quality of residences is more dynamic, uncontrolled, and prone to human behavioral changes. In consequence, measuring the health benefit gains derived from improving indoor air quality in residences is more complicated. To overcome this, a human thermal comfort model was first integrated with indoor microenvironment models, and subsequently linked with appropriate concentration–response and economic data for estimating the economic benefit gains derived from improving indoor air quality in residences for an adult and an elderly person. In this study, the development of the model is illustrated by using a typical residential apartment locating at the worst air quality neighborhood in Hong Kong and the daily weather profiles between 2002 and 2006. Three types of personal intervention measures were examined in the study: (i) using air cleaner in residence, (ii) changing time spent in residence, and (iii) relocating to a better air quality neighborhood. Our results revealed that employing air cleaners with windows closed in residence throughout the entire year was the most beneficial measure as it could provide the greatest annual health benefit gains. It would give a maximum of HK$2072 in 5-year cumulative benefit gain for an adult and HK$1700 for an elderly person. Employing air cleaners with windows closed in only cool season (October through March) could give the highest marginal return per dollar spent. The benefit gains would become smaller when windows were opened to a greater extent. By contrast, relocating to a better air quality neighborhood and changing the time spent in residence did not appeal to be beneficial intervention measures.

Given that Hong Kong is one of the most densely populated cities in the world, the exposure of the Hong Kong people is one of the interesting research areas. In this study, an indirect approach was used to estimate the exposure to nitrogen dioxide (NO2), respiratory dust (PM10) and carbon monoxide (CO) pollutants experienced by different age groups of people in Hong Kong. The average concentrations of the 20 major microenvironments obtained from our measurement survey data, together with the people activity pattern data obtained from 7-day recall questionnaires, were used to predict frequency distributions to exposure assessment. Our results showed that Hong Kong people spent more than 86% of their time indoors. Homes were shown to be the one of the major exposure sites to NO2, CO and PM10 for all age groups. Our results also indicate that the 24-h NO2 exposure for individuals, irrespective of age, spending more than 2 h in commuting daily, was observed to be exceeding the 24-h NO2 exposure standards. This study was one of the pioneering studies with valuable contribution for modeling the estimates of exposures to NO2, PM10 and CO of different age groups in Hong Kong. Keywords: Exposure measurement, Time activity pattern, Hong Kong

Vegetation is generally considered as an essential component for a sustainable city as it helps improve its microclimate environment and reduce greenhouse gases emissions. However, there is some evidence suggesting that adverse effects may be caused by tree-planting in shallow urban street canyons. Accordingly, we intended to investigate whether similar observations are found for different canyon geometries, i.e., canyons with aspect ratios higher than 1. Also, we attempted to investigate how the air quality varies with different tree planting densities by using CO as a representative for gas pollutant emitted from vehicle sources. The findings derived from CFD models indicate that tree planting elevates the CO levels inside canyons. Increasing the tree planting density can deteriorate the ventilation performance of canyons and to a greater extent for those with lower aspect ratios. However, the change in ventilation performance is less sensitive to a change in tree planting density at high planting densities. Accordingly, the decision in relation to tree planting in deep canyons should be weighed against other benefits like cooling effect, and energy saving. The findings should be of great value to urban planners in planning a sustainable city.