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Hong Kong buildings account for 90% of total electricity consumption and over 60% of greenhouse gas emissions. Therefore buildings present both a challenge and an opportunity for reduction in energy use and greenhouse gas emissions. Net Zero Energy Building (NZEB) and Net Zero Carbon Building (NZCB) are recognised as feasible strategies to reduce energy use and carbon emissions leading to a more sustainable built environment. While there is a growing number of NZEBs and NZCBs in relatively cool or temperate climates, there are relatively few examples in the subtropical climate, and in a densely populated city such as Hong Kong. This paper will examine the current progress towards a low carbon built environment in Hong Kong, zero energy/carbon design strategies and technologies applicable to building in a subtropical climate, and examines a case study of Hong Kong's first zero carbon building ZCB. ZCB's energy and carbon performance, experiences and lessons learned, and future directions are discussed. The paper will conclude with the challenges and opportunities for wider adoption of NZEBs and NZCBs in the Hong Kong construction industry. [ABSTRACT FROM AUTHOR]

Abstract: This paper is an extension to a paper previously published in the journal Building and Environment. Having determined an optimal recovery time in a controlled climatic environment, this paper aims to investigate the real impact on construction rebar workers by replicating the clinical experimentation to a series of field studies. Field studies were conducted during the summer time in Hong Kong. Nineteen rebar workers performed tasks of fixing and bending steel reinforcement bars on two building construction sites until voluntary exhaustion and were allowed to recover on site until their physiological conditions returned to the pre-work level or lower. Physiological Strain Index (PSI) was used as a yardstick to determine the rate of recovery. A total of 411 sets of meteorological and physiological data collected over fourteen working days between July and August of 2011 were collated to derive the optimal recovery time. It was found that on average a rebar worker could achieve 94% recovery in 40 min; 93% in 35 min; 92% in 30 min; 88% in 25 min; 84% in 20 min; 78% in 15 min; 68% in 10 min; and 58% in 5 min. Curve estimation results showed that recovery time is a significant variable to predict the rate of recovery (R 2 = 0.99, P < 0.05). Additional rest times should be introduced between works in extreme hot weather to enable workers to recover from heat stress. Frequency and duration of each rest time should be agreed among different stakeholders based on the cumulative recovery curve. [Copyright &y& Elsevier]

Abstract China has about 60 billion m2 of existing buildings, with approximately 2 billion m2 newly constructed each year. This accounts for half of all new buildings globally. A large number of buildings were demolished during the urban renewal process in China, significantly reducing the average lifespan of buildings and wasting vast amounts of energy and resources. However, the corresponding environmental impacts of reduced building lifespans have not been studied. Moreover, how to accurately evaluate future environmental impacts of construction projects is still a difficult problem, since in some cases the environmental impacts may not be realized for many years. In order to investigate the relationship between building lifespans and the corresponding environmental impacts, this paper first estimated the average lifespan of buildings in China through literature review, field investigation and calculation (using survival rate and demolition rate, respectively), revealing that the average building lifespan in China is from 25 to 35 years which is far shorter than the designed lifespans of buildings in China. It is also much shorter compared to the building lifespans in ten developed countries. Six buildings in Hebei Province in China were selected as case studies to conduct life cycle environmental (LCE) impact assessment. The results of the case studies indicate that (1) extending the building's lifespan from 30 to 50 years would reduce 40% of its total LCE impacts; (2) the environmental impacts caused by buildings (per area per year) in China is 2.3 times than that in the UK; (3) when environmental impacts are considered over time, they would decrease dramatically with the increase of discount rate, indicating that the buildings in developed cities in China with higher discount rates are more sensitive to environmental degradation. Highlights • The average lifespan of buildings caused by over demolition in China was estimated. • The building environmental impacts in different countries were examined. • Both life cycle embodied and operational environmental impacts were considered. • Time value of environmental impacts was also considered. [ABSTRACT FROM AUTHOR]

The feasibility of using thermal performance lines to assess the efficiency of using energy in air-conditioned commercial buildings in Hong Kong is being explored. The paper describes a regression study aimed at identifying a suitable climatic variable that would yield linear thermal performance lines for commercial buildings in Hong Kong. The study was based on the monthly electricity consumption of 26 existing office/commercial buildings obtained from a recent survey. Candidate weather parameters considered include monthly mean outdoor temperature, outdoor air moisture content and global solar radiation, and their square and product terms. The regression analysis shows that the square of monthly mean outdoor temperature would be the most appropriate climatic variable. Explanations are also given as to why moisture content and global solar radiation were considered less appropriate, notwithstanding that in Hong Kong, the humidity is high for most of the time in the year and the cooling load due to solar heat gain is a significant component of the design cooling load of air-conditioned buildings. [ABSTRACT FROM AUTHOR]

This paper selected typical flat and tower residential buildings in Beijing, China, to assess comfortable outdoor wind environments in summertime. Numerical analysis was carried out to evaluate design parameters that could influence the outdoor pedestrian-level wind environment during the summer. A total of twenty-seven valid cases using an orthogonal array, L 27 (3 13 ) orthogonal experimental design (OED) were selected. OED analysis showed significant probability and, therefore, the design parameters’ effects on the outdoor wind environment were quantitatively characterized at the pedestrian level. The conclusions were as follows: 1) design factors affecting the outdoor wind environment were found to be floor area ratio, façade direction, and greening rate; 2) the significance probability of design factors ranked highest to lowest in the order of greening rate > floor area ratio > façade direction > building arrangement. The results of such an evaluation can be used as an index for the planning and design process and for feedback of green building projects. [ABSTRACT FROM AUTHOR]

The development of green building in China has reached a new stage, needs to turn to the total energy consumption control from the technology control [1] . We should avoid packing technologies in green building projects and regard achieving good environmental performance as the fundamental goal. In this paper, we use the method of post-occupancy evaluation and regard the building environmental performance as the core of the evaluation system, in order to reduce the influence on the accuracy of results from the measures evaluation. We establish the evaluation index system of green public building environmental performance in severe cold and cold regions, including the index of building life-cycle carbon emissions accounting. And we set up the application plan of index and the scoring method, then we put forward a kind of evaluation grade based on environmental performance level, finally proposed the POE System of Green Public Building Environmental Performance in Severe Cold and Cold Regions (POE-GPBEPC). [ABSTRACT FROM AUTHOR]

Green real estate development is one of measures being implemented to reduce negative impacts of the building industry on the environment, society, and economy. However, there is lack of a systematic review of this large number of studies that is critical for the future endeavor. This paper reviews the existing body of knowledge related to green development. At first, the common research themes on green real estate development were identified, including concept, measure, business, and result. Then, the connotation and denotation of green real estate development was introduced in four dimensions. Third, the stakeholders of green real estate development and its benefits and costs were expatiated. Then, how to realize the green real estate development and its current weakness were analyzed in various aspects. It is found that the existing studies mainly focus on the environmental aspect of green building, other dimensions of sustainability of green building, especially the social sustainability is largely overlooked. Future research opportunities were identified such as the innovation of evaluation systems, integration of planning and design frameworks, management mechanisms and financing modes, and future proofing. [ABSTRACT FROM AUTHOR]

Abstract: This paper aims to investigate the effects of retrofitting existing public buildings in the “Hot Summer Cold Winter” climate region of China, using simulation and a case study, to see how retrofitted public buildings perform in the face of climate change in the region. This area of China is one of the most challenging regions for providing occupant comfort in buildings, with high demands for heating as well as cooling, together with high humidity levels. The simulation results suggest that energy reduction of up to 40% with improvements to the building enclosure is possible by retrofitting current existing public buildings to the new Chinese National Standard for the Zhejiang Province. Requirements for combating possible increase in energy consumption from heating and cooling demands due to future climate change was also investigated, and it was found that by simply improving U-Values of the building envelope to the new national standards set for the Zhejiang Province, the effects of future climate change can be nullified up to the 2080s. Further improvements to having similar standards as developed countries such as England and Wales will have less significance and cannot nullify the effects of climate change from the newly retrofitted public buildings. However, this can be achieved by involving other energy-saving strategies and installing suitable energy-saving technologies for the region. [Copyright &y& Elsevier]

Abstract: Operation mode of combined cooling heating and power (CCHP) system determines its energetic and environmental performances. This paper analyzes the energy flows of CCHP system and separated production (SP) system. The fuel energy consumptions of CCHP system following electrical demand management (EDM) and thermal demand management (TDM) are deduced respectively. Three indicators: primary energy saving, exergy efficiency and CO2 emission reduction, are employed to evaluate the performances of CCHP system for a commercial building in Beijing, China. The feasibility analysis shows that the performance of CCHP system is strictly dependent upon building energy demands. The selection of CCHP operation modes is systemically based on building loads, CCHP system and local SP system. The calculation results conclude that CCHP system in winter under EDM achieves more benefits than in summer. The sensitivity discussion indicates that the coefficient of performance for cooling and the efficiency of electricity generation are the most sensitive variables to the energetic and environmental performances of CCHP system. [Copyright &y& Elsevier]

Abstract: Building manufacturing creates product value like building space, and induces severe environmental influence at the same time. The idea of eco-efficiency (EE) can link a product or service value and the corresponding environmental influence together, but there has been little research that implements such idea on building manufacturing, such as the green building rating system of the comprehensive assessment system for building environmental efficiency (CASBEE) in Japan and the EcoEffect in Sweden. This paper proposes an emergy (spelled with an “m”) analysis-based methodology for EE evaluation of building manufacturing, where the building space (in cubic size) and the emergy amount of building manufacturing are selected as the indicators of product value and the environmental influence, respectively. Six residential buildings that include multi-storeys, moderate high-rises and high rises are selected averagely from two Chinese famous cities, namely Beijing and Shanghai. The evaluation results can provide directions to assess environmental influence and thus to heighten the EE of building manufacturing. The EE evaluation result can even be used as the base of a new green building (or eco-building) rating system. [Copyright &y& Elsevier]

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. [Copyright &y& Elsevier]

This study compared and analyzed both the energy savings and cost-effectiveness of various energy-saving technologies retrofitted to common buildings in China. Base models for an office and store building, set in representative climate zones of China-Beijing, Shanghai, and Guangzhou-were established and calibrated in EnergyPlus, a building energy simulation software program. Various energy-saving technologies were then applied to these models in EnergyPlus to calculate the overall energy savings under different climate conditions. In addition, a payback analysis was performed to determine the cost-effectiveness of each technology. The final results of this study can serve as a preliminary reference for selecting effective and economical energy-saving technologies to retrofit existing public buildings. [ABSTRACT FROM AUTHOR]