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• A constant-temperature thermal response test was proposed and demonstrated. • The new concept enables simultaneous heat injection and extraction tests. • A test data analysis method was developed based on the finite line source model. • Ground thermal conductivity was evaluated for both heat injection and extraction. • Convective effect enhanced ground heat transfer when heat injection was involved. Getting an accurate estimate of site-specific ground thermal conductivity from thermal response tests (TRTs) is crucial to the efficient and sustainable use of ground source heat pump systems. In a conventional TRT, the ground thermal conductivity is estimated by perturbing the ground with a positive heat injection and the response is measured in time. Despite the simplicity, the conventional TRT does not take into account the ground thermal response to cooling pulses. This may lead to mode-biased estimation due to the presence of natural convective effect. To address the problem, a constant-temperature TRT that comprises simultaneous heat injection and extraction was proposed. A test data analysis method was developed based on the finite line-source model. On this basis, a very first field test was performed in Taiyuan, China, demonstrating the use of the proposed TRT concept with full-scale measurements. Results show that, in the case of this field test, the ground thermal conductivities derived separately from heat injection and heat extraction are 1.83 W/(m K) and 1.65 W/(m K), respectively. The significant difference (10.9%) indicates that when heat injection is involved, the natural convective effect has enhanced ground heat transfer to increase the conductivity estimate. Thus, as compared to the conventional approach, the use of the proposed TRT can improve the characterization of the ground thermal response and conductivity. Relevant results and the test protocol reported in this study will be useful in providing the background information for this technology to be adopted in the ground source heat pump industry. [ABSTRACT FROM AUTHOR]

Though area in office buildings has expanded significantly in Hong Kong in the decade to 2013, increase in cooling energy use has been rather moderate. The factors and policy instruments that contributed to the impressive enhancement in energy usage efficiency are not available in published literature. Data of sixty-six office developments were examined to evaluate the role of policy instruments in bringing about the visible improvement. Numerical analyses reveal that use of chiller units with higher efficiency and fresh water cooling tower (FWCT) systems have contributed significantly to reduce cooling energy use of office space in Hong Kong. It is important to note that policies promulgated have played a key role in encouraging designers of office space to opt for energy efficient systems. The BEAM Plus certification for all public buildings has contributed the most (efficacy = 0.09) to the success in moderation of electricity consumption for cooling of office space. The FWCT scheme and the Building Energy Codes have had efficacies amounting to 0.076 and 0.026, respectively. Interestingly, the new OTTV requirement, used for regulation and monitoring of thermal performance of building envelopes, has had a negative rate of efficacy (0.018), implying that the government needs to review its appropriateness. [ABSTRACT FROM AUTHOR]

A novel dedicated outdoor air system consisting of a multi-stage direct expansion coil and a zero-energy heat pipe to generate extra-low temperature outdoor air to avoid moisture-related problems was proposed in this study. The proposed system’s performance in achieving the desirable air conditions and better energy efficiency objectives is compared with a conventional direct expansion system for air-conditioning of a typical office building in Hong Kong based on simulation investigations. The simulations were carried out using equipment performance data of a pilot study, and realistic building and system characteristics. It was found that the proposed system, as compared to the conventional system, could reduce the annual indoor discomfort hours by 69.4%. An energy and exergy analysis was also conducted. It was revealed that the proposed system could reduce the annual air-conditioning energy use by 15.6% and the system exergy loss rate by 13.6%. The associated overall exergy efficiency was also found 18.6% higher. The findings of this study confirm that the proposed system is better than the conventional system in terms of both energy and exergy efficiency and the desirable air conditions. [ABSTRACT FROM AUTHOR]

Increase in cooling energy usage of the residential sector in Hong Kong has been moderate in the most recent ten years (2004–2013). Factors and drivers responsible for this are of interest to policy makers in search of performance improvement but such information is not available in extant literature. This paper reviews the policy instruments introduced in Hong Kong during this period of time and examines the different engineering factors contributing to improvements in cooling energy efficiency. Whether the policy instruments have been instrumental in bringing about changes in engineering design and thus improvement in cooling energy efficiency is evaluated on the basis of the equipment and building envelope characteristics of 64 residential developments in Hong Kong. Different statistical analyses reveal that the use of more energy efficient room air-conditioning units (COP), smaller window-to-wall ratios (WWR) and walls with higher U-values are the engineering factors (WallU) that have contributed to moderation of growth of energy consumption; these were driven by policies introduced by the Hong Kong Government. Regarding the sensitivity of the three engineering factors, it was found that COP was the highest amounting to 0.455, followed in descending order by WallU and WWR. Their sensitivities were 0.289 and 0.006, respectively. [ABSTRACT FROM AUTHOR]

The use of SEHRAC (storage-enhanced heat recovery room air-conditioner) for space cooling and free water heating has been confirmed effective but its overall performance will unavoidably be affected by the associated increase in water temperature in the heat recovery water tank. Measures to enhance the heat storage capacity of the water tank will thus be beneficial to the overall performance of SEHRAC. But virtually none has been done to date. For achieving this objective, the use of PCM (phase change material) in the water tank was proposed in this study. A prototype SEHRAC integrated with an expanded graphite/paraffin composite PCM was designed and setup in a test facility for laboratory experiments. Two identical sets of experiments with and without the use of PCM (wPCM and woPCM scenarios) under a range of outdoor temperature conditions were conducted. It was found that the wPCM scenario, as compared to the woPCM scenario, the overall coefficient of performance was 6.9%–9.8% higher and the heat retention time of the tank water was 21.1% longer. The results confirmed that the performance of SEHRAC could be improved by the use of PCM. [ABSTRACT FROM AUTHOR]

The use of storage-enhanced heat recovery room air-conditioner (SEHRAC) to supply hot water and provide space cooling for energy saving has been confirmed effective, but the heat recovery process can lead to significant refrigerant pressure fluctuations. Whether an expansion device can function properly despite the fluctuations is decisive to the successful use of SEHRAC. Capillary tube (CT) and thermostatic expansion valve (TEV) are the two most used expansion devices in SEHRAC, but a suitable type has never been identified in extant literature. In this study, laboratory experiments were conducted to enable a side-by-side comparison of the two expansion devices. A prototype SEHRAC, which could be switched between the CT and TEV systems, was designed and setup in a test facility for two identical sets of experiments. For each set of experiments, a series of tests under different outdoor temperatures were conducted. It was found that an overall better performance was achieved by the TEV system. The space cooling and water heating capacities were on average 16.3–19.4% and 18.5–23.4% larger than the CT system. The overall coefficient of performance was also found 12.5–20.9% higher. The results confirmed that TEV is preferred for use in SEHRAC. [ABSTRACT FROM AUTHOR]

Effectiveness of SEHRAC (storage-enhanced heat recovery room air-conditioner) for water heating in residential buildings in Hong Kong and elsewhere has been confirmed in previous studies. However, given these studies assumed a theoretical maximum recoverable heat, whether its use is still energy effective in practice, in particular under intermittent operation, is of concern. Intermittent operation of the SEHRAC can lead to significant fluctuations in operating conditions. Adding that capillary tube is often used as the expansion device to magnify the fluctuations, whether SEHRAC can still operate satisfactorily despite the fluctuations is another concern. To address these concerns, a prototype which can be switched between the combined CH (cooling and heating) mode and the CC (conventional cooling) mode was set-up for laboratory experiments. The results showed that the water heating objective can be achieved. The operating parameters also confirmed the satisfactory operation of SEHRAC. Energy performance of the CH mode was found better than the CC mode. A prediction model was developed for evaluating the use of SEHRAC. On wider application of SEHRAC, energy use of the residential sector in Hong Kong can be reduced by 9.1%. The experimental details described in this study would become an experiment protocol to enhance future research in this area. [ABSTRACT FROM AUTHOR]

China building energy codes (CBEC) have been introduced for over two decades but little has been publicized in literature. LEED on the contrary is the most publicized building environmental assessment scheme. To enable better understanding of the compliance standards of CBEC, this paper presents the energy performance assessment results (represented by energy and energy cost savings) of three office buildings in China (one in Beijing and two in Shanghai) using the current versions of CBEC and LEED. The energy and energy cost savings of the three buildings were predicted based on hour-by-hour simulations using the weather data and energy tariffs of Beijing and Shanghai where the three studied buildings are located, and their actual building and system characteristics. The study revealed that LEED in general sets more stringent requirements than CBEC in indoor design conditions, building envelope characteristics and air-conditioning system features. Amongst various building end uses, energy use for air-conditioning was found dominating the assessment results, and the use of energy efficient measures not forming part of the baseline criteria, could lead to 2 to 5% reduction in the overall building energy use. The two schemes were benchmarked against BEAM Plus and their weaknesses were also unveiled. [ABSTRACT FROM AUTHOR]

Factors 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 = RA and City One Shatin = 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 3.4–13.3% of the property price, compared to 0.6–5.5% for architectural attributes. [ABSTRACT FROM AUTHOR]

Highlights: [•] Use of storage-enhanced heat recovery room air-conditioner (SEHRAC) for free water heating was investigated. [•] Investigations were based on a typical residential estate in Hong Kong. [•] Accurate predictions of the amount of recoverable heat and household water heating demand were conducted. [•] Deliverables included also the design requirements of the storage tank for dense living environment. [•] Water heating energy and energy cost savings, as well as CO2 emission reduction was estimated to be 9.3%. [ABSTRACT FROM AUTHOR]

Highlights: [•] This is an experimental study of the use of DCDV system for achieving the decoupling and energy saving objectives. [•] The study focuses on side-by-side comparison of the DCDV and conventional systems. [•] DCDV system can better achieve the desired space air conditions and is more energy efficient. [•] A prediction model has been developed to relate the possible condensation period with different operating parameters. [•] The results are useful for wider application of DCDV system. [ABSTRACT FROM AUTHOR]

Highlights: [•] Energy assessment of current versions of LEED and BEAM Plus were compared. [•] Comparison was based on three office buildings – one in Beijing and two in Shanghai. [•] Energy assessment result was found dominated by the energy use for air-conditioning. [•] Assessment results were comparable for buildings assessed by LEED and BEAM Plus. [•] Comparable results would not be affected by difference in tariff between locations. [Copyright &y& Elsevier]

Highlights: [•] Metrics of 5 building environmental assessment schemes reviewed and benchmarked. [•] Assessment scope of BREEAM and LEED were found most comprehensive. [•] Rating systems of BRREEM, BEAM Plus and ESGB were found more stringent. [•] Two-phase certification method was concluded a preferred approach. [•] Moderate agreement reached on weights and ranks of weights allocated to key issues. [•] Performance requirements between LEED and BEAM Plus are comparable. [Copyright &y& Elsevier]

Abstract: Desiccant cooling system for active humidity control and to conserve energy has been in commercial applications for over two decades. However, its use in humid wet markets has never been examined. A gas-fired desiccant cooling system has been installed in a wet market in Hong Kong. In this study, the annual energy saving in conjunction with the use of desiccant cooling system was investigated by in-situ measurements, site surveys and simulations. The verified computer model was used for further simulations. It was found that for the use of a minimum ventilation rate of 10.3 L/s/person, the use of desiccant cooling system as compared to conventional system saved 4% of the energy and could achieve the desired space conditions. A parametric study under various ventilation rates indicated that use of desiccant cooling system in wet markets in hot and humid Hong Kong would lead to energy and energy cost savings, as well as CO2 emission reduction amounting from 1% to 13%. The savings were more evident when wet markets were designed for a ventilation rate of 20 L/s/person. Furthermore, the actual occupancy profile, and lighting and small power densities determined in this study would be useful for future studies on wet market. [Copyright &y& Elsevier]

Abstract: View 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 (θ) 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. [Copyright &y& Elsevier]

Abstract: BREEAM, LEED, CASBEE, BEAM Plus and Chinese ESGB have been formally launched at different stages in the last twenty years. How well the certified and rated buildings compare with each other is always an interest of building designers and policy-makers. This paper presents a side-by-side comparison of energy use assessments of the five schemes. The comparisons are on the assessment method and criteria, default parameters, trade-offs allowed, performance scales, approved simulation tools, performance indicators and assessment results. Comparison results showed that all the five schemes are based on relative performance. It was also found that despite the variations in default parameters among the five schemes, market positions of certified buildings are comparable. LEED was found to be the most stringent and relatively less flexible in its assessment criteria. Nonetheless, the energy cost budget approach, adopted only by LEED, is able to fulfil emission reduction and cost saving objectives on the condition that a “fuel neutral” approach should be adopted. [Copyright &y& Elsevier]

Abstract: The combined use of dedicated outdoor air ventilation (DV) and dry cooling (DC) air-conditioning system to decouple sensible and latent cooling for desirable space air conditions, better indoor air quality, and energy efficiency is proposed for hot and humid climates like Hong Kong. In this study, the performance and energy saving potential of DCDV system in comparison to conventional systems (constant air volume (CAV) system with and without reheat) for air conditioning of a typical office building in Hong Kong are evaluated. Through hour-by-hour simulations, using actual equipment performance data and realistic building and system characteristics, the cooling load profile, resultant indoor air conditions, condensation at the DC coil, and energy consumptions are calculated and analyzed. The results indicate that with the use of DCDV system, the desirable indoor conditions could be achieved and the annual energy use could be reduced by 54% over CAV system with reheat. The condensate-free characteristic at the DC coil to reduce risk of catching disease could also be realized. [Copyright &y& Elsevier]

Abstract: Recent research studies advocates decoupling dehumidification from cooling to improve indoor air quality and reduce energy consumption. The feasible use of heat pipe at the air handler dedicated for outdoor air treatment (HPDV system) in accomplishing this objective is investigated in this study. To evaluate the performance and the energy saving potential of the proposed HPDV system, the design parameters of 75 Grade A office buildings in Hong Kong were collected. Ten representative buildings were subsequently identified for further study to achieve a confidence level of 95%. The annual cooling load profiles of the 10 representative buildings were simulated by the use of HTB2. Based on the realistic cooling load profiles and the heat pipes of effectiveness 0.35–0.6, the proposed HPDV system in achieving the intended objectives were evaluated. It was found that the savings for the 10 representative buildings were comparable. The reduction in cooling and reheating energy was between 23 and 44kWh/m2, which corresponds to 1.2% and 7.9% saving in annual energy use for air-conditioning. The results indicate that HP of different effectiveness can be applied to save energy for over 70% of the air-conditioned hours; of which only 0.03–6.3% of the time the decoupling objective cannot be achieved (abbreviated as NHRS). Based on the results of the study, a simplified model relating NHRS with heat pipe effectiveness has been established. The model can help designers more quickly determine how NHRS can be weighted against other factors such as the additional plant room space and the financial implications. The results confirm the feasible use of the HPDV system in achieving the intended objectives for subtropical climate like Hong Kong where air-conditioning demand is highly variable, and is required year-round. [ABSTRACT FROM AUTHOR]

Abstract: Hong Kong is well-known as a high population density city. Residential buildings are often located near busy roads. Residential units with good environmental quality are becoming scarce. Homebuyers are willing to pay a premium for a better environmental quality of which indoor air quality and indoor noise level are the two most important attributes. Traffic is a shared source for noise and air pollution. The influence of distance from road on the decay of traffic-induced noise and air pollutions are of interest to homebuyers and residents. However, recent studies on the combined impact of traffic-induced noise and air are focused on the pedestrian exposures. In this study, a series of noise level and PM10 concentration measurements were conducted at roadsides of two busy roads in Hong Kong and at ten case study residential units located nearby. The noise level measurements aim at establishing a measurement protocol to identify case study units that are directly exposed to road traffic and the air passage is free from external screening for the subsequent traffic-induced PM10 concentrations evaluation. Regression analysis on the measurement results indicates that both the traffic-induced noise and the PM10 concentrations at the case study units exhibit a linear correlation with the logarithm of their corresponding distance from road (logR). The result confirms that “logR” can be adopted as a common parameter for evaluating the combined impact of road traffic on the noise and air pollutions of a residential unit. [ABSTRACT FROM AUTHOR]

Abstract: The combined space cooling and hot water preheating system that utilizes the rejected condenser heat is considered one of the most cost effective energy conservation measures. However, simultaneous consumption characteristics are absent in public domain. Questionnaire surveys have been conducted to obtain the relevant information from 126 households residing in high-rise public rental residential buildings in Hong Kong, achieving a confidence level of 95%. The candidate households were selected by a convenience sampling approach, and the questionnaire was constructed using either forced-choice format or in numeric response format. The data obtained were verified by correlation analysis. Data collected includes the occupancy pattern, the installed air-conditioner and water heater characteristics, and the utilization pattern of air-conditioning and hot water. Based upon the collected data and site measurements, hourly, daily and monthly heat recovery and hot water heating demand profiles were established, as well as the correlation between tap water and outdoor air temperatures. The combined profiles enable the evaluation of the feasible use of the combined system, and for future sizing of hot water storage tanks. The potential energy and fuel cost saving associated with the use of the proposed combined system for typical public rental housing in Hong Kong was estimated to be 50%. [Copyright &y& Elsevier]

Abstract: Residential air-conditioning becomes a common feature in our daily life. They are typically installed at high level known as ceiling-based system (CAC). With the increasing use of floor-based air-conditioning system in commercial buildings for energy saving, it is proposed in this study to locate a top discharge/front return air-conditioner at floor level to resemble a floor-based air-conditioning system (FAC) to curb energy use in residential buildings. Given the concerns about draught discomfort and thermal stratification associated with floor-based air-conditioning systems, the objective of this study is to evaluate the air distribution performance and to quantify the possible energy benefits. Bedroom was chosen as a sensitive case for detailed air distribution performance evaluation. Experimental study, CFD simulations and energy simulations were conducted in achieving the specific objectives. CAC and FAC were installed in a bedroom-like environmental chamber for experimental study at different indoor and outdoor conditions. The air velocities and temperatures at various positions and levels inside the chamber were measured to determine the air distribution performance indices (ADPI) and airflow draft risk (DR). The cooling output, power consumption and coefficient of performance (COP) of the two units were measured and calculated for comparison. The experimental results show that ADPI of CAC and FAC are 92.3% and 84.6%, respectively. COP of FAC is 8.11% higher than CAC, and the corresponding DR are comparable. The experimental results were used to validate the CFD simulations as well as providing actual performance data for predicting the energy use of applying CAC and FAC in a case-study building. CFD simulations and draught assessment confirmed that there is no potential draught discomfort and thermal stratification associated with the use of FAC. Energy simulations predicted that the associated energy saving is 6.9%. Wider use of FAC in residential buildings is therefore recommended. [Copyright &y& Elsevier]

Abstract: An experimental study on the performance of a domestic water-cooled air-conditioner (WAC) using tube-in-tube helical heat exchanger for preheating of domestic hot water was carried out. The main aims are to identify the comprehensive energy performance (space cooling and hot water preheating) of the WAC and the optimum design of the helical heat exchanger taking into account the variation in tap water flow rate. A split-type WAC was set up for experimental study at different indoor and outdoor conditions. The cooling output, the amount of recovered heat, and the power consumption for different hot water flow rates were measured. The experimental results showed that the cooling coefficient of performance (COP) of the WAC improves with the inclusion of the heat recovery option by a minimum of 12.3%. This can be further improved to 20.6% by an increase in tap water flow rate. Same result was observed for the comprehensive COP of the WAC. The maximum achievable comprehensive COP was 4.92 when the tap water flow rate was set at 7.7L/min. The overall heat transfer coefficient of the helical heat exchanger under various operating conditions were determined by Wilson plot. A mathematical model relating the over all heat transfer coefficient to the outer pipe diameter was established which provides a convenient way of optimising the design of the helical heat exchanger. [Copyright &y& Elsevier]

Abstract: Mandatory energy codes to curb energy use of residential buildings have been formally launched in China for more than two decades but little has been publicized in literature. Similar codes are not available for residential buildings in Hong Kong, but most residential buildings in Hong Kong, especially public housing estates, are HK-BEAM certified to demonstrate their compliance with regulatory and basic design requirements. Given HK-BEAM is internationally recognized and there are doubts about the effectiveness of the China codes, how the energy efficiency of the HK-BEAM certified buildings compare with buildings in compliance with the China codes is of interest to most building designers and policy makers. This paper describes how the energy efficiency of a case study building in compliance with the China codes compare with the one in compliance with HK-BEAM. The energy simulation by HTB2 and BECRES reveal that the case study building in compliance with the China codes is 51.1% better in energy use. In the study, the relative impact of each compliance criterion on energy use and cooling load has been quantified by sensitivity analysis. The sensitivity values indicate that energy use is most sensitive to air-conditioning operation hours, indoor design temperature, coefficient of performance (COP) of the room air-conditioners (RAC) units, and the envelop characteristics. The results of this study indicate that a HK-BEAM certified building cannot satisfy the China codes requirements. This provides good reference to the policy makers, the building owners, and to the China and Hong Kong Governments when considering reciprocal recognition of building energy codes. [Copyright &y& Elsevier]

Abstract: Water-cooled air-conditioning systems (WACS) are widely used in the commercial sector for energy efficiency, but not in the domestic sector. It has been found that there are no mathematical models and energy simulation programs to enable detailed investigation and evaluation into the energy performance of water-cooled air-conditioners. To improve the applicability of water-cooled air-conditioners in the domestic sector, the development of a prediction model for energy performance analysis is needed. This paper addresses the development of an empirical model for predicting the operational performance and energy consumption for the use of water-cooled air-conditioners. The model consists of four sub-models which has taken into account the energy consumption of the condenser water system. A prototype WACS was set up and tested in an environmental chamber to validate the resultant model. The overall COP of the WACS was found to be greater than 3 at 90% rated capacity. The predictions from the model compared well with the experimental results, with RMS error within 11%. [Copyright &y& Elsevier]

Abstract: The objective of this study is to conduct a realistic prediction of the potential energy saving for using water cooled air conditioners in residential buildings in Hong Kong. A split type air conditioner with air cooled (AAC) and water cooled (WAC) options was set up for experimental study at different indoor and outdoor conditions. The cooling output, power consumption and coefficient of performance (COP) of the two options were measured and calculated for comparison. The experimental results showed that the COP of the WAC is, on average, 17.4% higher than that of the AAC. The results were used to validate the mathematical models formulated for predicting the performance of WACs and AACs at different operating conditions and load characteristics. While the development of the mathematical models for WACs was reported in an earlier paper, this paper focuses on the experimental works for the AAC. The mathematical models were further used to predict the potential energy saving for application of WACs in residential buildings in Hong Kong. The predictions were based on actual building developments and realistic operating characteristics. The overall energy savings were estimated to be around 8.7% of the total electricity consumption for residential buildings in Hong Kong. Wider use of WACs in subtropical cities is, therefore, recommended. [Copyright &y& Elsevier]

In the present study, a simple numerical function is proposed for use together with the time–frequency analysis in the detection of very weak sinusoidal signals embedded in a non-stationary random broadband background noise. Its performance is studied through the use of two numerical examples. It is found that the present method enables good recovery of the sinusoidal signals and the instants of their initiations even when the signal-to-noise ratio is down to −17dB. [Copyright &y& Elsevier]

Abstract: Optimizing system configuration is always an interest of building designers. By statistical analysis of the design data of 50 commercial buildings in Hong Kong and the performance data of 186 chiller models, it is ascertained that the chiller capacity and the fraction of full-load capacity have little influence on the system’s energy performance. Following on this, this paper presents an evaluation of the energy performance of a multiple-chiller system consisting of 2–10 equally sized chillers. Such an analysis was based on performance data from three major manufacturers. It is found that the energy efficiency of multiple-chiller system improves with a higher number of chillers, and the maximum saving is estimated to be 9.5%. Based on the results of the study, a simplified model relating energy use with number of chillers has been established. The model can help designers more quickly determine how the energy efficiency can be weighted against other factors, such as the additional plant room space and the financial implications. [Copyright &y& Elsevier]

Abstract: The latest (4/04 and 5/04) versions of the Hong Kong Building Environmental Assessment Method (HK-BEAM), one covering new buildings and the other existing buildings, have been formally launched in 2005. The paper describes the building energy performance assessment method in these latest HK-BEAM versions. With the use of the energy budget approach, the assessment framework is applicable to a wide range of buildings that may comprise different mixes of premises types. The new scheme provides bonus credits for provisions that allow utilization of renewable energy sources. For existing buildings, it makes allowances for plant performance degradation and constraints to implementation of improvement measures in existing buildings. So far, the new assessment method has been applied to six building developments, including commercial complexes and residential developments. The assessment results are presented and discussed in the paper. [Copyright &y& Elsevier]

Cytochrome P450 (CYP) 2C8 is a principle enzyme responsible for the metabolism of many clinically important drugs as well as endogenous compounds such as arachidonic acid. The enzyme is genetically polymorphic but a simple method is not available to study its genetic polymorphism. We developed and optimized a variant-specific PCR techniques to detect CYP2C8*2, CYP2C8*3 and CYP2C8*4.Genomic DNA was extracted from blood using standard extraction methods. A two-step PCR method was developed to detect simultaneously three CYP2C8 variants. In the first PCR (PCR1), specific regions from exons 3, 5 and 8 of the CYP2C8 gene were amplified. The products were used as templates in parallel alleles-specific PCR (PCR2). This method was tested against DNA samples obtained from 57 healthy Malaysian volunteers.The bands of interest were successfully amplified. This method showed specific and reproducible results when tested on healthy volunteers. DNA sequencing further confirmed genotype results obtained from current method.We have successfully developed and optimized a multiplex PCR method suitable for use in population studies of CYP2C8 polymorphism. [Copyright &y& Elsevier]

Buildings are the dominant energy consumers in modern cities but their consumption can be largely cut back through improving efficiency, which is an effective means to lessen greenhouse gas emissions and slow down depletion of non-renewable energy resources. However, the potential energy cost saving alone is hardly a sufficient incentive to investing into improvement measures, unless the cost of using energy soars. People''s attitude will change with increasing concerns about the environment and sustainable development but the results remain insignificant. Surely, more effective means are needed to induce or compel greater efforts, especially to the signatories to the Kyoto Protocol. Whilst regulatory control is widely used, many believe that encouraging voluntary commitments is more cost effective in dealing with environmental problems. More researchers now favor the adoption of a well-articulated policy mix involving both regulatory and voluntary instruments. The paper describes a comprehensive literature review about regulatory and voluntary policy instruments related to building energy efficiency. Particular attention is given to the cost-effectiveness of these instruments, as reflected by the implementation experience of several countries, and a qualitative evaluation. The possibility and benefits of harmonizing governmental and private-sector schemes are discussed. [Copyright &y& Elsevier]

Within a given budget, selection of the optimal set of measures for enhancing the energy efficiency of a building is often based on the relative order of the feasible measures, prioritised according to either the life cycle cost saving or the economic benefit–cost ratio of the measures. A sensitivity analysis shows that, compared to the life cycle cost analysis, the benefit–cost ratio analysis is less susceptible to the influence of uncertainties in the estimates of the present value of the life cycle energy saving and cost. Where interactive measures are involved, the effects of some are dependent on the co-existence of other measures. The prioritisation determined according to the benefit–cost ratios of individual measures, each taken in the absence of all the others, can lead to the choice of a range of measures that is below optimal. Selection of the optimal set of energy efficiency enhancement measures requires a multistep approach, which is exemplified by the case study described in the paper. [Copyright &y& Elsevier]

Many, but not all, rebate-type demand side management (DSM) programmes worldwide have met with success. The rebate rate offered is a critical factor to success but a rational rebate scale determination method that would help strike a proper balance between the incentive offered and the effectiveness of the programme is lacking. For the DSM programmes recently launched in Hong Kong, the rebate rates are disproportionate to the cost and performance of the promoted energy-saving measures, resulting in diverse participation rates among the programmes. This paper presents a conceptual framework for formulating the rebate scales for incentive-based DSM programmes for commercial buildings, which would attract participation of building owners and boost electricity saving. The establishment of the scale starts from developing a performance curve that relates the cost effectiveness and the long-term benefits of different energy-saving DSM measures. The rebate scale is set based on the premise that a proportionally higher rebate rate should be offered for the adoption of each additional measure, which would yield a diminished marginal rate of return. Analysis showed that replacing the current rebate scale by the proposed scale would lead to benefits, both to the building owners and the utility companies. [Copyright &y& Elsevier]

Regulatory control forms the bedrock of the environmental policies of many countries. Whilst this interventionist approach can ensure a certain minimum standard would be achieved, far greater results can be achieved if it is augmented by a voluntary assessment-scheme. The benefits of having both approaches are explored in the paper with reference to the building energy codes and a voluntary building environmental-performance assessment scheme HK-BEAM, both of which are being implemented in Hong Kong. Quantification of the possible range of energy saving was based on the design characteristics of 22 commercial buildings in Hong Kong. The need for and the benefits of using the energy assessments within HK-BEAM as an alternative compliance route to the building energy codes are confirmed and the compliance criteria are established. The potential energy-saving through the use of the regulatory and the voluntary-based approaches were estimated to be from about 8% to more than 30%. [Copyright &y& Elsevier]

Residential buildings represent a predominant source of energy consumption in most subtropical cities. To enhance the energy performance of this sector, the use of reversible room air-conditioners (RRACs) for combined space heating and domestic hot water (DHW) production is proposed. The idea arises from the fact that in subtropical regions RRACs sized for cooling always have excessive heating capacities to allow a parallel production of DHW. In order to assess the techno-economic feasibility of the proposed initiative, a representative housing estate in Hong Kong consisting of 12,800 residential units was selected for an extensive simulation study. Results confirmed the technical viability of the proposed system. It was found that a wide adoption of the technology has the potential to reduce 7.7% of Hong Kong residential energy consumption and 744,192 t of CO 2e emissions. The tolerable capital cost (TCC) approach was adopted for yearly economic viability analysis. The average TCC for individual residential units was found ranging from HK$2,241 to HK$26,286 depending on the household size, electricity price, and economic settings. This study provides preliminary evidence to confirm the viability of the proposed technology and opens a new way for residential energy savings in Hong Kong and elsewhere in the subtropical. • A techno-economic investigation on use of room air-conditioners for combined space and DHW heating. • A simulation-based analysis was conducted to assess its techno-economic viability. • Energy savings were estimated as 7.7% for its widespread use in Hong Kong housing. • Energy-related emission reductions were estimated as 744,192 t of CO2 e. • Incentive measures may be required to promote the technology in Hong Kong. [ABSTRACT FROM AUTHOR]

Replacement of air-cooled chillers with water-cooled chillers for air-conditioning plants in existing buildings can yield a significant amount of energy savings, especially in a sub-tropical climate. However, due to variations in weather conditions and building operation patterns, the amount of actual energy saving is often uncertain in these retrofits. These uncertainties impose a risk of saving shortfalls when Energy Service Companies (ESCOs) guarantee building owners for a certain amount of energy savings in Energy Performance Contracting (EPC) projects. This study presents a probabilistic approach to estimating a range of possible energy savings with the associated confidence levels for chiller replacement in existing buildings, taking into account the annual variations in the influential parameters affecting energy savings. The influential factors include building cooling loads, system control and operation systems, as well as chiller plant characteristics. The proposed approach involves: the use of correlation analysis for identifying influential parameters; EnergyPlus for simulating energy use of chiller plant; and a Monte Carlo approach for simulating the probability of post-retrofit energy savings. A commercial building where the air-cooled chillers were replaced with water-cooled chillers is used to illustrate the proposed approach. Results show that the variations in annual energy savings for chiller replacement projects can be estimated with a defined degree of certainty. In the case study project, the possible annual energy savings during the post-retrofit period range from 1,149,000 kWh (37.6% of baseline consumption) to 1,504,000 kWh (49.2% of ditto) at 90% statistical significance. The risk mitigation measures for this type of energy retrofit are discussed as well. [ABSTRACT FROM AUTHOR]

Compared with conventional energy retrofit projects, Energy Performance Contracting (EPC) projects present a different risk picture to the contracting parties as its primary focus is to deliver promised energy savings to building owners (hosts). This study aims to identify the key risks inherent in EPC projects, and investigate the hosts’ concerns on the use of EPC, as well as propose practical measures to enhance the wider adoption of EPC. Two separate questionnaire surveys were conducted with respondents comprising ESCOs ( n = 34) and hosts ( n = 168) in Hong Kong. Results indicate that the key risks to ESCOs are possible payment default of hosts after installation, uncertainty of baseline measurement, and increase in installation costs in EPC projects. For hosts, their primary concerns in considering the use of EPC include possible long payback periods, project complexities and repayment ability. In addition, the respondents agree with three practical measures to enhance the adoption of EPC in future, including the promotion of successful projects, modification of government procurement practices, and government's backup of loans. The findings of this study provide useful pointers to key stakeholders of EPC projects for harnessing their risk perceptions and mitigating their concerns on this procurement approach. [ABSTRACT FROM AUTHOR]

Abstract: A dysregulated immune response and functional immunosuppression have been considered the major mechanisms of the bacterial sepsis syndrome. More recently, the loss of endothelial barrier function and resultant microvascular leak have been found to be a key determinant of the pathogenesis of bacterial sepsis. Whether a similar paradigm applies to systemic viral syndromes is not known. Answering this question has far-reaching implications for the development of future anti-viral therapeutic strategies. In this review, we provide an overview of the structure and function of the endothelium and how its barrier integrity is compromised in bacterial sepsis. The various in vitro and in vivo methodologies available to investigate vascular leak are reviewed. Emphasis is placed on the advantages and limitations of cell culture techniques, which represent the most commonly used methods. Within this context, we appraise recent studies of three viruses – hantavirus, human herpes virus 8 and dengue virus – that suggest microvascular leak may play a role in the pathogenesis of these viral infections. We conclude with a discussion of how endothelial barrier breakdown may occur in other viral infections such as H5N1 avian influenza virus. [Copyright &y& Elsevier]

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 μg/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 μg/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 μg/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. [Copyright &y& Elsevier]

Abstract Background The epidemiology of mucormycosis in the era of modern diagnostics is relatively under-explored. Objectives To examine the contemporary epidemiology, clinical manifestations, diagnosis and causative pathogens of mucormycosis. Data sources Ovid MEDLINE and Ovid EMBASE from January 2000 to January 2017. Study eligibility criteria Published case reports/series of proven/probable mucormycosis. Participants Patients ≥18 years old. Methods Patient characteristics, disease manifestations and causative pathogens were summarized descriptively. Categorical variables were assessed by chi-square test or Fischer's exact test, and continuous variables by the Wilcoxon–Mann–Whitney or Kruskal–Wallis test. Risk factors for the different clinical manifestations of mucormycosis were identified using multivariate logistic regression. Results Initial database searches identified 3619 articles of which 600 (851 individual patient cases) were included in the final analysis. Diabetes mellitus was the commonest underlying condition (340/851, 40%) and was an independent risk for rhino-orbital-cerebral mucormycosis (odds ratio (OR) 2.49; 95% CI 1.77–3.54; p < 0.001). Underlying haematological malignancy was associated with disseminated infection (OR 3.86; 95% CI 1.78–8.37; p 0.001), whereas previous solid organ transplantation was associated with pulmonary (OR 3.19; 95% CI 1.50–6.82; p 0.003), gastrointestinal (OR 4.47; 95% CI 1.69–11.80; p 0.003), or disseminated (OR 4.20; 95% CI 1.68–10.46; p 0.002) mucormycosis. Eight genera (24 species) of Mucorales organisms were identified in 447/851 (53%) cases, of which Rhizopus spp. (213/447, 48%) was the most common. Compared with other genera, Rhizopus spp. was predominantly observed in patients with rhino-orbital-cerebral mucormycosis (75/213, 35% versus 34/234, 15%; p < 0.001). Death was reported in 389/851 (46%) patients. Mortality associated with Cunninghamella infections was significantly higher than those caused by other Mucorales (23/30, 71% versus 185/417, 44%; p < 0.001). However, Cunninghamella spp. were isolated primarily in patients with pulmonary (17/30, 57%) or disseminated disease (10/30, 33%). Conclusions Findings from the current review have helped ascertain the association between various manifestations of mucormycosis, their respective predisposing factors and causative organisms. [ABSTRACT FROM AUTHOR]

Abstract: We have investigated the dielectric and magnetic properties of the spin-1/2 compounds Ba3Cr2O8 and Sr3Cr2O8. For Ba3Cr2O8, the real part dielectric constant ε′(T) exhibit a frequency-independent peak near the Jahn-Teller transition temperature T JT = 70 K. However, no anomaly in the ε′(T) curve is observed near T JT = 275 K for the isostructural compound Sr3Cr2O8. The difference in the ε′(T) behaviors may be attributed to the different onset temperatures of the phonon mode splitting in the samples. Dielectric relaxation analysis revealed that extrinsic contribution due to Maxwell–Wagner effect dominated at high temperatures for both compounds. The magnetization data reveal the occurrence of antiferromagnetic interactions between the Cr5+ ions and the χ(T) curves can be described by the Bleaney–Bowers equation for both compounds. [Copyright &y& Elsevier]

Abstract: Two statistical tests, namely the Jarque–Bera and the D’Agostino tests, originally adopted for checking data normality are used to recover the initialization of an exponentially growing wave embedded inside a stationary background noise in the present investigation both numerically and experimentally. Such type of signal is very important especially in building services engineering where the early detection of very small alien signals in the systems is crucial to the smooth operation of a heavily serviced building. The effects of the background noise magnitude on the accuracy of the recovery process are examined. The numerical simulation results show that these statistical tests are very sensitive to the change incurred by the wave to the background noise statistics and they are very helpful in locating the instant of the wave initialization even when the signal-to-noise ratio drops to −30dB. A new parameter derived from the parameters of these two statistical tests, which is easy to compute, is proposed and its performance is found to be better than those of the two tests. It is also demonstrated that the performance of the new parameter does not depend much on the background noise. The experimental results are in line with the numerical simulations. [Copyright &y& Elsevier]

Abstract: Background: Propofol is an anesthetic with pluripotent cytoprotective properties against various extrinsic insults. This study was designed to examine whether this agent could also ameliorate the infamous toxicity of doxorubicin, a widely-used chemotherapeutic agent against a variety of cancer diseases, on myocardial cells. Methods: Cultured neonatal rat cardiomyocytes were administrated with vehicle, doxorubicin (1μM), propofol (1μM), or propofol plus doxorubicin (given 1h post propofol). After 24h, cells were harvested and specific analyses regarding oxidative/nitrative stress and cellular apoptosis were conducted. Results: Trypan blue exclusion and MTT assays disclosed that viability of cardiomyocytes was significantly reduced by doxorubicin. Contents of reactive oxygen and nitrogen species were increased and antioxidant enzymes SOD1, SOD2, and GPx were decreased in these doxorubicin-treated cells. Mitochondrial dehydrogenase activity and membrane potential were also depressed, along with activation of key effectors downstream of mitochondrion-dependent apoptotic signaling. Besides, abundance of p53 was elevated and cleavage of PKC-δ was induced in these myocardial cells. In contrast, all of the above oxidative, nitrative and pro-apoptotic events could be suppressed by propofol pretreatment. Conclusions: Propofol could extensively counteract oxidative/nitrative and multiple apoptotic effects of doxorubicin in the heart; hence, this anesthetic may serve as an adjuvant agent to assuage the untoward cardiac effects of doxorubicin in clinical application. [Copyright &y& Elsevier]

Abstract: Overlapping neurodegenerative pathologies (including Alzheimer''s disease, AD) have been described in Parkinson''s disease (PD) patients with leucine-rich repeat kinase-2 (LRRK2) mutations. We analyzed a LRRK2 PD (R1628P) risk variant in a group of 885 subjects comprising of AD and controls. The frequency of the R1628P allele was higher in AD compared to controls (3.5% vs. 1.6%, OR 2.3, 95 CI 1.2–4.4, p =0.018). In vitro, the mean percentage of apoptosis and cell death observed for the R1628P transfected human cell lines was higher compared to wild type 21.8±1.9, vs. 17.1±1.3, p <0.05, 30.2±2.2 vs. 25.7±1.3, p <0.05). The LRRK2 R1628P variant increases the risk of AD in our population and our in vitro findings suggest that it is a functional variant and predisposes to apoptosis. [Copyright &y& Elsevier]

Abstract: Genetic variants of the neuronal sortilin-related receptor (SORL1) have been demonstrated to modulate the risk of Alzheimer''s disease (AD) in different American and European populations [Rogaeva, E., Meng, Y., Lee, J.H., Gu, Y., Kawarai, T., Zou, F., Katayama, T., Baldwin, C.T., Cheng, R., Hasegawa, H., Chen, F., Shibata, N., Lunetta, K.L., Pardossi-Piquard, R., Bohm, C., Wakutani, Y., Cupples, L.A., Cuenco, K.T., Green, R.C., Pinessi, L., Rainero, I., Sorbi, S., Bruni, A., Duara, R., Friedland, R.P., Inzelberg, R., Hampe, W., Bujo, H., Song, Y.Q., Andersen, O.M., Willnow, T.E., Graff-Radford, N., Petersen, R.C., Dickson, D., Der, S.D., Fraser, P.E., Schmitt-Ulms, G., Younkin, S., Mayeux, R., Farrer, L.A., St George-Hyslop, P., 2007. The neuronal sortilin-related receptor SORL1 is genetically associated with Alzheimer disease. Nat. Genet. 39 (2), 168–177]. We conducted haloptype analysis involving two genetic clusters of SORL1 in AD and controls among Han Chinese. rs3824968 (SNP 23) was associated with an increased risk of AD, and there was a trend towards association for rs1699102 (SNP 22) and rs2282649 (SNP 24). More robust associations were found for three-loci haplotypes. In particular, the GCA haplotype at SNPs 19–22–23 was associated with an increased risk (odds ratio 1.4), and CTC haplotype at SNPs 19–22–23 and TCT at SNPs 22–23–24 a decreased risk (odds ratio 0.67) of AD. The complete absence of some at-risk North European haplotypes in our Chinese study subjects was likely due to different ancestral origins, with allelic heterogeneity among races. However, our study suggests that certain SORL1 haplotypes at SNPs 19–24 modulated risk of AD in our Chinese population. [Copyright &y& Elsevier]

A comparative study of the expression of metabotropic glutamate receptor 2/3 (mGluR2/3) was done in the hippocampus of rats and mice after pilocarpine-induced status epilepticus (APISE), and of patients with mesial temporal lobe epilepsy. At 1 day APISE, there was a marked increase in mGluR2/3 immunoreactivity in the stratum lacunosum moleculare (SLM) of CA1 area and in the middle one-third of the molecular layer (MM) of the dentate gyrus. Immuno-electron microscopic study showed degenerating mGluR2/3 positive axons in the SLM of CA1 area at 1 day APISE. From 7 days, mGluR2/3 immunopositive product decreased, and by 31 days APISE, it almost disappeared in two-thirds of the SLM near CA2. In the mouse model at 2 months APISE, mGluR2/3 immunopositive product in two-thirds of the SLM near the stratum radiatum disappeared, and so did in the whole SLM of CA1 area in patients with mesial temporal lobe epilepsy. Neuropharmacological study by intravenous injection of mGluR2/3 agonist 2R,4R-4-aminopyrrolidine-2,4-dicarboxylate [(2R,4R)-APDC] at different doses at 1 h during pilocarpine induced status epilepticus showed that (2R,4R)-APDC could not stop seizures and neuronal death in the hilus of the dentate gyrus. The present study, therefore, suggests that the reduction of mGluR2/3 immunopositive product in the SLM of CA1 is a consequence of neuronal loss in either the entorhinal cortex or CA1 area of the hippocampus, and at the dosage range from 12.5 to 600 mg/kg, (2R,4R)-APDC may not be effective in the prevention of seizures or neuronal death in the hilus of the dentate gyrus. [Copyright &y& Elsevier]

Aim: To validate the effectiveness of CYP2C19-LAMP assay for the detection of CYP2C19 ∗2 and CYPC19 ∗3 in comparison with real time PCR melting curve analysis. Methods: CYP2C19-LAMP primers were essentially adapted from Iwasaki M et al. [1]. The LAMP reaction was optimized at a temperature range from 58°C to 62°C. DNA were extracted from whole blood samples collected from forty patients suffering from acute coronary syndrome in a single center of Hong Kong. With the addition of SYBR Green, LAMP results were examined visually in ambient light and also under UV illumination at 365nm. Real-time PCR melting curve analysis was done by LightMix Kit human CYP2C19 ∗ 2 and CYP2C19 ∗ 3 (TIB Molecular Biology). The two variants exhibit Tm 48.1[o]C and 59.2[o]C and were detected by LightCycler 480 II. Results: CYP2C19-LAMP assay successfully detectedCYP2C19 ∗2 and CYPC19 ∗3 mutants. Our study found that the assay time of CYP2C19-LAMP assay was only 30 min whereas real time PCR melting curve analysis was 60min. We observed that the temperature requirement was very stringent and any temperature outside 60°C might result in non-specific amplifications. In the LAMP assay, non-specific amplifications were observed with an error rate of 5% (8/160) and resulted in 15% (6/40) being mistyped. These non-specific amplifications, however, could be resolved with duplicated runs. A trial of one heat treated heparinized blood sample was found to be sustainable in LAMP reactions without prior DNA extraction. Conclusions: We showed that CYP2C19-LAMP assay was a simple, rapid and cost- effective method for CYP2C19 genotyping. Owing to the stringent temperature requirement in LAMP assay, the test is recommended to be run in duplicate with better quality control in obtaining a more reliable result by a thermal cycler. [ABSTRACT FROM AUTHOR]

Abstract: In a case control study involving 484 study subjects, we showed that the CALHM1 allele (13.5% vs 16.7%) and genotype frequency was not significantly different between Alzheimer''s disease (AD) and controls. Logistic regression analysis did not reveal any interaction between ApoE4 allele and CALHM1 allele. [Copyright &y& Elsevier]