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Integrated Part Load Value (IPLV) has been adopted worldwide as a simple metric for regulating and evaluating chiller performance. There is no exception for Hong Kong. However, the weighting factors and working temperatures for the derivation of IPLV were developed for the US. They may not be appropriate for use in other countries/regions with different operating conditions. Europe and China therefore have developed their own formula but the formulation is based on simulations and details cannot be found in literature. This study adopts a carefully-designed methodology to develop a Hong Kong specific IPLV. The development was based on actual operating characteristics of 20 Grade A office buildings in Hong Kong. Representativeness of the 20 office buildings was verified by statistical analysis. Through in-situ measurements and site surveys, hour-by-hour operating data of the studied buildings were collected. Monte Carlo analysis and ASHRAE's bin method were employed to examine the massive volume of operating data. Regression analysis was employed to formulate the Hong Kong specific IPLV. The formulated IPLV was validated. It gives the highest weighting to 75% capacity (0.682), followed in descending order are 50% capacity (0.257), 25% capacity (0.049) and 100% capacity (0.012). In determining the working temperatures, a mathematical model to enable quick estimation of entering condenser water temperature for water-cooled chillers was developed. The results and methodology adopted in this study will be useful for reference of manufacturers, policy makers and researchers in searching for a reliable metric for performance evaluation of chillers should simulation is not practical.

Overcooling causes thermal discomfort and wastes energy. Effectiveness of a novel dedicated outdoor air system (DOAS) consisting of a multi-stage direct expansion coil to generate extra-low temperature (XT) outdoor air to handle the entire space cooling demand for better energy and humidity control has been confirmed in previous studies. In these studies, the terminal system was assumed using variable air volume (VAV) without reheating. The conventional VAV system without reheating has overcooling problem. This is associated with uncertain fluctuations of operating characteristics. However, virtually no study has been done to investigate its overcooling risk, and how it is compared with XT-DOAS. In this study, a rigorous probabilistic approach is proposed to account for the uncertain fluctuations of operating characteristics to assess their overcooling risks. Monte Carlo simulations with 10,000 interactions was used for risk analysis. A morphing method was employed to develop 10,000 weather files that could give an accurate prediction of future variations in yearly weather conditions. Reliable datasets were used to develop the probability distribution functions to account for the daily variations in use patterns. The most probable operating characteristics were input to EnergyPlus for hour-by-hour simulations. The annual cooling load profile formulated by the probabilistic approach was successfully validated by in-situ measurements. The probabilistic assessment results show that XT-DOAS has far less overcooling hours and lower long-term percentage of dissatisfied than the conventional VAV system. The results also indicate that the proposed probabilistic approach is useful for a robust system performance evaluation.

Cooling energy use of residential buildings in Hong Kong has been increasing in the past two decades. Natural ventilation is an effective means to reduce cooling energy use. To encourage wider and ...

Natural ventilation and the type of window used are closely related. Many works have already been done on identifying the window types that can enhance ventilation performance in residential buildings. However, window performance has been investigated either independently, without considering the interactive effects of other apertures (relative positions of windows and window orientations) or it has been examined based on very limited wind data sets. To fill this research gap, this study aims to evaluate the influence of window types on indoor ventilation performance of residential units in Hong Kong, taking into account the interactive effect and based on representative wind data sets. Air change per hour (ACH) was used to quantify natural ventilation. In this study, site measurement was conducted at a carefully selected residential unit to provide data for validation of the Computational Fluid Dynamics (CFD) settings. The validated settings were used for further CFD simulations. The Central Composite Design method and the Squeeze Theorem were used to determine the representative wind data sets. The Response Surface Regression method was used to develop a mathematical model for quantifying the interactive influence of different apertures on indoor ventilation and to enable quick estimation of ACH. The results lead to the conclusion that for all apertures, side hung (SH) window is the most effective design, followed in descending order by top hung (TH) window and sliding (SLD) window. The maximum achievable ACH for SH and TH windows were 124% and 97% higher than the SLD window. It was also found that if windows can be located only on the same side of a residential unit, SH windows and south facing TH windows should be preferred.

An accurate estimate of site-specific underground thermal properties from thermal response tests (TRTs) is vital to the efficient and sustainable use of ground source heat pump (GSHP) systems. During a conventional TRT, the ground is perturbed by a heat injection and the response is measured in time. Despite the simplicity of the concept, conventional TRT fails to take into account the ground thermal response to heat extraction, which may affect the reliability of the thermal properties derived. To address the problem, an improved TRT based on both heat injection and extraction was proposed in this study. The improvements were demonstrated with an in-situ test carried out in Taiyuan, China. The measurement results showed that the ground thermal conductivity in Taiyuan was 1.56 W/(m K) and the borehole thermal resistance was 0.22 (m K)/W. The results also showed that, in the case of Taiyuan, ground thermal conductivities derived solely from heat injection test and heat extraction test were, respectively, 7.6% higher and 8.3% lower than that from the improved TRT. Thus, compared with the conventional TRT, the improved TRT consisting of both heat injection and extraction tests can provide test data more accurately reflect the annual performance of GSHP systems.

Angelman syndrome (AS) is a neurodevelopmental disorder with unique behavioral phenotypes, seizures, and distinctive electroencephalographic (EEG) patterns. Recent studies identified motor, social communication, and learning and memory deficits in a CRISPR engineered rat model with a complete maternal deletion of theUbe3agene. It is unknown whether this model recapitulates other aspects of the clinical disorder. We report here the effect ofUbe3amaternal deletion in the rat on epileptiform activity, seizure threshold, and quantitative EEG. Using video-synchronized EEG (vEEG) monitoring, we assessed spectral power and epileptiform activity early postnatally through adulthood. While EEG power was similar to wild-type (WT) at 1.5 weeks postnatally, at all other ages analyzed, our findings were similar to the AS phenotype in mice and humans with significantly increased δ power. Analysis of epileptiform activity in juvenile and adult rats showed increased time spent in epileptiform activity in AS compared with WT rats. We evaluated seizure threshold using pentylenetetrazol (PTZ), audiogenic stimulus, and hyperthermia to provoke febrile seizures (FSs). Behavioral seizure scoring following PTZ induction revealed no difference in seizure threshold in AS rats, however behavioral recovery from the PTZ-induced seizure was longer in the adult group with significantly increased hippocampal epileptiform activity during this phase. When exposed to hyperthermia, AS rat pups showed a significantly lower temperature threshold to first seizure than WT. Our findings highlight an age-dependence for the EEG and epileptiform phenotypes in a preclinical model of AS, and support the use of quantitative EEG and increased δ power as a potential biomarker of AS.

Status epilepticus (SE) is a prevalent disorder associated with significant morbidity, including the development of epilepsy and mortality. Cardiac arrhythmias (i.e. inappropriate sinus tachycardia and bradycardia, asystole, and atrioventricular blocks) are observed in patients following SE. We characterized ictal (during a seizure) and interictal (between seizure) cardiac arrhythmogenesis following SE using continuous electrocardiography and video electroencephalography (vEEG) recordings throughout a 14-day monitoring period in an intrahippocampal chemoconvulsant mouse model that develops epilepsy. We quantified heart rhythm abnormalities and examined whether the frequency of cardiac events correlated with epileptiform activity, circadian (light/dark) cycle, the presence of seizures, and survival during this period of early epileptogenesis (the development of epilepsy) following SE. Shortly following SE, mice developed an increased interictal heart rate and heart rhythm abnormalities (i.e. sinus pause and sinus arrhythmias) when compared to control mice. Heart rhythm abnormalities were more frequent during the light cycle and were not correlated with increased epileptiform activity or seizure frequency. Finally, SE animals had early mortality, and a death event captured during vEEG recording demonstrated severe bradycardia prior to death. These cardiac changes occurred within 14 days after SE and may represent an early risk factor for sudden death following SE.

In Energy Performance Contracting (EPC) projects, Energy Service Companies (ESCOs) often provide guarantees on the energy savings of proposed retrofit measures based on a simplified engineering method. In order to assess the risk of saving shortfalls, there is a need to develop an evaluation method based on the probabilistic approach. This study focuses on a proposed probabilistic approach to evaluate the performance risks of common lighting retrofit measures such as replacement of existing lighting, installation of daylight-linked lighting controls and occupancy-based controls. The proposed approach considers the variations in the influential factors affecting energy performance, including daylight availability, occupancy rates, lamp conditions and lighting use patterns. Empirical data is used to develop the probability distribution functions of those influential factors. A hypothetical 40-storey office building with typical design features (such as regularly shaped open plan) in Hong Kong was modeled using EnergyPlus to demonstrate the application of this probabilistic approach. The results indicate that the variations in actual energy savings can be substantial in lighting retrofit projects, ranging from 1,267,000 kWh (43% of pre-retrofit consumption) to 1,927,000 kWh (65% ditto) with 90% statistical significance, posing risk on the achievement of guarantee savings in an EPC project setting.

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.

Sleep is a dominant part of our daily lives. People often have sleeping habits. Sleeping habit is referred as the preferred bedding system (type of bedding and sleepwear) and thermal environment. Thermal environment and cooling energy use are closely related. Many works have been done on sleep quality, sleeping habits, and the associated cooling energy use. However, it is noted that they are either separately or pairwise investigated. No investigations to date have been done to investigate their interactive effect. This study serves as a pilot study to fill the research gaps in investigating the interactive effect of sleep quality, sleeping habits and cooling energy use. Based on the use of three bedding systems and four temperature settings, 12 sleeping tests, each refers to one sleeping habit, were performed simultaneously in eight subjects. Sleepbot was employed to quantity sleep quality. Upon ascertaining the best sleep quality for different bedding systems, hour-by-hour energy simulations using EnergyPlus were conducted. It was found that for the use of light bedding systems, the associated drop in energy use would be 78.3% and 37.8% for female and male subjects respectively. Two prediction models, one relating energy use with thermal environment, and the other relating sleep quality with sleeping habit, have been established. The models can help quickly determine the tradeoff amongst sleep quality, sleeping habit and energy use.

The heat source types in China were not limited to the coal, other types of energy were introduced into the heating energy consumption in recent years, and therefore the specific regional impact of the heating emissions could not be obtained accurately according to the current achievement. Based on this, this study aimed to quantify the impact of the heating emissions on the air quality in an efficient and accurate way. A new method was proposed for investigating the quantitative impact of the heating emissions on the air quality index in this paper and its assumptions and accuracy were verified as well. The data employed in this method is extracted from Ministry of Environmental Protection Data Centre, Qingyue open source and Shanghai Central Meteorological Observatory. The key prerequisites of the proposed method were discussed in this study. By calculating, the averaged absolute difference of the meteorological parameters, namely Clo, WD, WS and P, is 3.58%, 2.40%, 3.21% and 3.94%, respectively. The difference ratio of the industrial emissions relative to the total emissions is as low as 4.3%. The optimal principal component number is six for the proposed method, which can satisfy the accuracy requirement with minimum workload. Compared with the results in previous similar studies, the proposed method showed excellent performance in analyzing the regional impact of the heating emissions on ambient air quality in China. Moreover, a total of 64 North cities in China were analyzed based on the proposed method to promote the knowledge on the influence of heating emissions on the environmental quality and the related parameters were provided in this study.

The fresh water supply is finite, but the fresh water demand is infinite. A sustainable supply of fresh water is emerging as one of the most critical resource issues in the world. Hong Kong is one of the highest per capita fresh water users in the world. This has led to many government initiatives to promote water-saving habits in Hong Kong. However, after almost a decade of efforts, there has been no obvious reduction in consumption. Little has been done to identify the reason for this. Through the use of questionnaire surveys, site measurements, and controlled experiments, the aim of this study is to investigate the level of adoption of different water-saving habits, the most influential water-saving habits, and the barriers to the adoption of water-saving habits in residential buildings in Hong Kong. It was found that if the policies are targeted to break the identified barriers, then there is a potential for reducing the total domestic fresh water consumption in Hong Kong by 14.7%. It was also found that the knowledge of water scarcity and good water use habits are not the barriers to the adoption of water-saving habits in Hong Kong households. Rather, the government should draw public&rsquo, s attention to the environmental impact of water usage and the high fresh water consumption level of Hong Kong people to break the knowledge barrier and should re-examine the water tariff to break the motivation barrier. The results of this study provide useful information for decision makers in the context of water conservation in Hong Kong as well as elsewhere in the world.

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 CO2e 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.

Transom window (TW) has been demonstrated to be effective in enhancing natural ventilation in high-rise residential buildings in tropical climates. However, virtually no work has been done to investigate whether a naturally-ventilated hybrid system (using enhanced ventilation created by TW supplemented with air-conditioning (AC)) is effective in reducing cooling energy consumption and providing the desired thermal comfort. For this purpose, cooling energy usage of an AC only system is compared with that of a hybrid system for achieving the same thermal comfort in high-rise residential buildings in Hong Kong. In this study, a carefully-designed methodology which involves the use of market survey, statistical analyses, site measurements, and integration of CFD and EnergyPlus simulations was adopted. Market surveys and statistical analyses were used to provide reliable input data for simulations. Site measurements of ventilation were used to assess the uncertainty of CFD simulation results. The integration of CFD and EnergyPlus simulations were for accurate predictions of natural ventilation performance (ACH) and air velocities achieved with TWs, hour-by-hour air temperatures, and hour-by-hour cooling energy use of the hybrid and the AC only systems. The simulated air velocities and temperatures were used for thermal acceptability analysis. It was found that depending on the TW design, average improvement in ACH ranges from 117% to 190%, and the associated cooling energy saving from hybrid system ranges from 22.2% to 22.7%. The results confirm the effective use of TW in reducing cooling energy use and providing thermal comfort in high-rise residential buildings in Hong Kong.

Demand controlled ventilation (DCV) to conserve energy while maintaining an acceptable indoor environment has been used for over 30 years. However, little work has been done on evaluating its energy saving potential in cooling dominant office buildings in subtropical climate. In this study, the energy saving potential of DCV system for use in six representative office buildings in Hong Kong was investigated by simulations. Simulation validation was done based on in situ measurements and site surveys. The findings show that, based on their original design conditions, the use of DCV could lead to 12.5–26.1% energy saving. To facilitate quick estimation of the energy saving potential of DCV system, further simulations were performed for the development of a simplified model. The simplified model relates the energy saving potential to key air-conditioning system and design parameters. Based on the simplified model, sensitivity analysis was conducted to quantify the influences of different parameters on the energy saving potential of DCV system. The developed model method can be used for prediction on the energy saving potential in a wider application of DCV in Hong Kong.

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.

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.

A novel dedicated outdoor air system consisting of a multi-stage direct expansion coil to generate extra-low temperature outdoor air to avoid moisture-related problems and for desirable air conditions and better energy efficiency is proposed for investigation. In this study, the proposed system's (extra-low temperature-dedicated outdoor air system) performance in achieving the desirable air conditions and better energy efficiency objectives is compared with a conventional direct expansion coil system with variable speed compressor and fan used for air conditioning of a typical office building in Hong Kong. Through hour-by-hour simulations, using equipment performance data of a pilot study and realistic building and system characteristics, it was found that the extra-low temperature-dedicated outdoor air system, as compared to the conventional system, could reduce the annual air-conditioning energy consumption by 22.6%, the indoor discomfort hours by 31% and the condensation risk to zero hours. Root-mean-s...

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.

It has been a common practice to place room air-conditioners (RACs) at overhead level for cooling of residential environments because this offers better air distribution performance and thus thermal comfort. However, now reversible RACs are gaining ground and they comprise both cooling and heating modes. Whether the same practice of locating RACs at overhead level should continue for reversible RACs has never been investigated. This study is the first ever attempt to identify the optimum positioning (position and level) for installation of reversible RACs in a representative bedroom. Computational Fluid Dynamics (CFD) and EnergyPlus simulations were integrated for the purpose and experiments were conducted in an environmental chamber to provide data for validation of the CFD settings. EnergyPlus simulations were used to determine the hour-by-hour cooling and heating demands based upon realistic operating and probable equipment characteristics. The probable equipment characteristics were ascertained by an extensive market survey and Monte Carlo analysis. The hour-by-hour cooling and heating demands were analysed by Central Composite Design method and the Squeeze Theorem for the formulation of the representative cooling and heating data sets for further CFD simulations. Further CFD simulations provide an accurate prediction of air temperatures and velocities for different installation positioning for thermal comfort analysis. Revised air diffusion performance indices (ADPIs) were developed to facilitate thermal comfort analyses for cooling and heating modes. It was found that slightly higher ADPIs can be obtained when the reversible RAC is installed at high level and on the longer side of the bedroom.

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.

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.

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.

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.

Effectiveness of dry cooling and dedicated ventilation (DCDV) system for decoupling dehumidification from cooling to achieve the desired indoor condition and condensate-free objectives for air-conditioning of office environments in Hong Kong has been confirmed in previous simulation and experimental studies by the authors. However, our previous studies assumed a constant outdoor air and chilled water flow rates, and this is not always the case in practice. Whether this assumption could affect the effectiveness of DCDV system is the subject of present investigation. A prototype that could enable the variation of outdoor air and chilled water flow rates, as well as indoor and outdoor conditions, was set up for laboratory experiments. Our results have illustrated the effectiveness of DCDV system in achieving the intended condensate-free objective which was most affected by the space-sensible heat ratio and chilled water flow rate. Little influence was found to be introduced by the outdoor air flow rate and outdoor air conditions. The results, through sensitivity and statistical analysis, were found consistent with results of our previous studies.

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.

Angelman syndrome (AS) is a genetic neurodevelopmental disorder, most commonly caused by deletion or mutation of the maternal allele of the UBE3A gene, with behavioral phenotypes and seizures as key features. Currently no treatment is available, and therapeutics are often ineffective in controlling AS-associated seizures. Previous publications using the Ube3a maternal deletion model have shown behavioral and seizure susceptibility phenotypes, however findings have been variable and merit characterization of electroencephalographic (EEG) activity. In this study, we extend previous studies comparing the effect of genetic background on the AS phenotype by investigating the behavioral profile, EEG activity, and seizure threshold. AS C57BL/6J mice displayed robust behavioral impairments, spontaneous EEG polyspikes, and increased cortical and hippocampal power primarily driven by delta and theta frequencies. AS 129 mice performed poorly on wire hang and contextual fear conditioning and exhibited a lower seizure threshold and altered spectral power. AS F1 hybrid mice (C57BL/6J × 129) showed milder behavioral impairments, infrequent EEG polyspikes, and fewer spectral power alterations. These findings indicate the effect of common genetic backgrounds on the Ube3a maternal deletion behavioral, EEG, and seizure threshold phenotypes. Our results will inform future studies on the optimal strain for evaluating therapeutics with different AS-like phenotypes.

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/ft2 (5.8%) and HK$886.8/ft2 (28.2%), respectively, for RA and HK$1672.7/ft2 (31.9%) and HK$111.5/ft2 (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., Highlights • Key architectural and environmental attributes affecting property price were identified. • Willingness to pay (WTP) and elasticity of substitution (ES) of the key attributes were determined using the hedonic price approach. • Homebuyers were found to be valuing the environmental attributes much higher than the architectural attributes. • The WTP and ES values as well as the findings revealed in this study are valuable information to building developers and homebuyers.

a b s t r a c t Storage-enhanced heat recovery room air-conditioner (SEHRAC) is considered one of the most effective measures to curb energy use in residential dwellings. However, little has been done on optimal design of the storage tank. For application in dense living environment like Hong Kong, another concern is whether or not the amount of recoverable heat can meet the household water heating demand. In this study, a typical residential estate in Hong Kong was chosen for supply and demand analysis. The analysis was based on hour-by-hour simulations using actual building characteristics and previously identified utilization patterns. It was found that with the use of SEHRAC, the daily cumulative recoverable heat far exceeds the daily household water heating demand. For optimal design of the storage tank, an air-conditioner model (REFMOD) was developed to enable ascertaining the operating parameters at the refrigerant side of SEHRAC. Other design requirements of the storage tank including the minimum required heat storage capacity and heat transfer effectiveness were determined. The potential energy and energy cost savings, as well as CO2 emission reduction for wider application of SEHRAC were estimated as 9.3% of the overall contribution of the residential sector in Hong Kong.

The combined use of dry cooling (DC) system and dedicated ventilation (DV) system to decouple cooling and dehumidification process for energy efficiency was proposed for subtropical climates like Hong Kong. In this study, the energy performance and condensation risk of the use of DCDV system were examined by analyzing its application in a typical office building in Hong Kong. Through hour-by-hour simulation using actual equipment performance data and realistic building and system characteristics, it was found that with the use of DCDV system, the annual energy consumption could be reduced by 54% in comparison with the conventional system (constant air volume with reheat system). In respect of condensation risk, it was found that the annual frequency of occurrence of condensation on DC coil was 35 h. Additional simulations were conducted to examine the influence of different parameters on the condensation risk of DCDV system. Measures to ensure condensate-free on DC coil were also discussed.

The use of DCDV system for decoupling dehumidification from cooling to achieve energy saving objective for air-conditioning of office environments in Hong Kong was confirmed effective based on simulation studies by the authors. However, given that simulation typically assumes a perfect control and feedback system, whether or not the benefits of DCDV system can be realized in practice, in particular under various space part load ratio (PLR) and sensible heat ratio (SHR) conditions, is subject to experimental verifications. In this study, a prototype which could be switched between the proposed DCDV system mode and the conventional system mode was constructed in a test facility for laboratory experiments. Through two sets of identical experiments under various space cooling load conditions, it was found that if compared to the conventional system, DCDV system could perform slightly better in achieving the desired indoor condition and in reducing the moisture-related air quality problems, but would result in 1–3% higher in cooling output. As for the overall coefficient of performance (COP o ), the DCDV system was found performed better by 5.6–7.2%. Additional experimental analysis was conducted for the development of a prediction model to relate the possible condensation period ( ψ ) on the DC coil with different operating parameters.

LEED and BEAM Plus have been formally launched for more than 10 years. They are the two most recognized building environmental assessment schemes in China. Previous works have been done on benchmarking the energy assessment of the two schemes. However, benchmarking was either based on their earlier versions of which substantial changes have been made, or focused on their assessment issues and metrics without making reference to actual building characteristics. This paper compares the energy performance assessment results of three new office buildings in China (one in Beijing and two in Shanghai) using current versions of LEED and BEAM Plus. The three office buildings were chosen for their similarities in design. The study revealed that despite the variations in different aspects between LEED and BEAM Plus, assessment results of the three studied buildings were comparable. Amongst various building end uses, energy use for air-conditioning was found dominating the assessment results. Comparison results also show that although different tariff systems are adopted in Beijing and Shanghai, the difference will not affect the assessment results as long as same tariff system is used for predicting the energy cost of the baseline and design cases.

Buildings are key target of policies that aim at promoting environmentally sustainable development. Amongst policy instruments that address environmental burdens incurred by buildings, labelling and certification schemes are arguably the most cost-effective. Since the first building environmental assessment scheme was launched in the 1990's, similar schemes have emerged in about 30 countries. These are mainly domestic schemes tailored to suit local contexts. Whilst most of these schemes take a voluntary, market driven approach, some have become a part of mandatory building approval requirements, though different certification schemes may co-exist in some regimes. Benchmarking the strengths and characteristics of different schemes has been advocated. In this connection, this paper provides a comprehensive review and comparison of the issues and metrics of five representative assessment schemes, namely, BREEAM, LEED, CASBEE, BEAM Plus and the Chinese scheme ESGB. Comparison of these five schemes shows that BREEAM and LEED are the most comprehensive. A two-phase certification method is adopted in LEED, CASBEE and BEAM Plus, which is considered preferable. Statistical analysis also reveals that there is a moderate degree of agreement amongst the five schemes on weights and ranks of weights allocated to five key assessment aspects. Through comparison, the weighting coefficients adopted by ESGB were found the most representative. Strengths and characteristics of the five schemes have been identified for reference of policy makers in developing their domestic schemes.

The combined use of dry cooling air-handler and dedicated ventilation (DV) system for energy saving and better indoor condition has been confirmed effective. But the application of this system is hindered by the condensation risk on dry cooling coil. In this study, the condensation risk of the use of dry cooling air-handler and dedicated ventilation (DCDV) system in subtropical climates was examined by analysing its application in a typical office building in Hong Kong using actual equipment performance data and realistic system characteristics. Through hour-by-hour simulations it was found that the annualised cumulative frequency of occurrence of condensation (ConHR) for normal operation of the office building was acceptable. However, departures of the in-use condition from design values are inevitable. Additional parametric studies were therefore performed to evaluate the influence of five design parameters on the ConHR, and to identify the influential factors. By statistical analysis, it was found that ConHR was most sensitive to changes in system latent load, followed by (descending order) system sensible heat ratio, system total load and design moisture absorption coefficient of dry cooling coil. Furthermore, a regression model relating ConHR to latent load, sensible heat ratio, total load and design moisture absorption coefficient was established for minimising condensation risk during the design of DCDV system.

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., Highlights • The study is motivated by an actual desiccant cooling system installed in a wet market in Hong Kong. • The study focuses on side-by-side comparison of the desiccant and conventional systems. • Desiccant cooling system can better achieve the desired space air conditions. • Desiccant cooling system can lead to energy, energy cost and CO2 emission savings. • The results are useful for wider application of alternative energy source for cooling of wet markets.

PurposeAs part of a study that aimed at enhancing the future roles and functions of building services (BS) engineers in Hong Kong, a survey was carried out to obtain demographic information about BS practitioners as well as their views and opinions on a range of issues which affect professional practices of BS engineers and recognition of their contributions by others. The purpose of this paper is to give a portrait of BS engineers in Hong Kong.Design/methodology/approachA series of statistical analyses were conducted based on the responses given by the BS practitioners, which included their qualifications, experience, job field, annual income and the number of trades of BS systems that they are competent in and responsible for.FindingsThe statistics show that: competence gap exists in that BS engineers are required to handle more trades of BS systems than those they are competent in; and the academic and professional qualifications, years of experience and job position are the key influential factors to the annual income of BS engineers but little differences exist in the average annual income of engineers in different job fields.Originality/valueThe competence gap is a concern that needs to be addressed to ensure BS engineers are competent in handling the common trades of BS systems, which is increasingly important for them to perform effectively in integrated professional teams for turning out holistic solutions for sustainable building developments.

Visual Abstract, Numerous studies have shown epilepsy-associated cognitive deficits, but less is known about the effects of one single generalized seizure. Recent studies demonstrate that a single, self-limited seizure can result in memory deficits and induces hyperactive phosphoinositide 3-kinase/Akt (protein kinase B)/mechanistic target of rapamycin (PI3K/Akt/mTOR) signaling. However, the effect of a single seizure on subcellular structures such as dendritic spines and the role of aberrant PI3K/Akt/mTOR signaling in these seizure-induced changes are unclear. Using the pentylenetetrazole (PTZ) model, we induced a single generalized seizure in rats and: (1) further characterized short- and long-term hippocampal and amygdala-dependent memory deficits, (2) evaluated whether there are changes in dendritic spines, and (3) determined whether inhibiting hyperactive PI3K/Akt/mTOR signaling rescued these alterations. Using the PI3K inhibitor wortmannin (Wort), we partially rescued short- and long-term memory deficits and altered spine morphology. These studies provide evidence that pathological PI3K/Akt/mTOR signaling plays a role in seizure-induced memory deficits as well as aberrant spine morphology.

Excessive lead has been found in drinking water in Hong Kong in tests carried out in 2015. Investigations have identified that the problem in public rental housing estates was caused by the problematic solders used in the plumbing, and recommendations on enhancing the quality control system and strengthening the relevant water quality standards have been proposed. The cause for the same problem happening in other premises where soldering has not been adopted for water pipe connections is left unidentified. Considering the unidentified cause and the recommendations made, this study aims to identify the gaps in practice followed in Hong Kong for safeguarding the water quality of new installations. A holistic review of governing ordinances and regulations, products and materials used and the testing and commissioning requirements adopted in Hong Kong and elsewhere in the world were conducted. Based on international practices and parametric analysis, it was found that there are gaps in practices followed in Hong Kong, which are directly and indirectly leading to the lead-in-water crisis. Recommendations for improvement in the quality control system, and the water quality standards including the allowable lead content and leaching limit for products and materials and the testing and commissioning requirements on plumbing installations have been made. The review and the identified gaps would become useful reference for countries in strengthening their relevant water quality standards.

Natural ventilation in residential dwellings is very important for occupants’ health and comfort. Previous studies by the authors have concluded that natural ventilation performance in dwellings can be enhanced by positioning the two groups of window openings (bedroom windows and living room windows) in opposite directions or perpendicular to each other; and/or the use of side-hung windows. However, the buildings selected for those studies were located in an isolated site, for the purpose of focused evaluation of the influence of various configuration parameters and window types. However, in Hong Kong, buildings are tightly packed. In this study, the influence of urban environment was thoroughly considered. A residential estate was identified to represent typical characteristics of the urban environment in Hong Kong for CFD modelling and simulations. Bi-variate correlations and K-means cluster analyses were adopted to identify a set of probable local wind conditions, which took into account the co...

PurposeThe purpose of this paper is to narrow the diverse views of the industry stakeholders on two controversial issues, namely the scope of core competence of building services engineers (BSEs) and the statutory role that they should play, which were encountered in an extensive research study on the building services profession of Hong Kong.Design/methodology/approachAn expert panel was formed and the Delphi method was applied to resolve the controversies. In the Delphi process, every panel member was provided with complete opinions expressed by all other panel members in each round of the deliberation.FindingsSufficient support was found for the proposition that professional BSEs should be competent in handling air‐conditioning, electrical, fire services, and plumbing & drainage works, and that the government authorities should mandate the design and compliance certification of electrical and fire services installations by BSEs.Research limitations/implicationsAlthough the Delphi method has not been hitherto applied to resolve the controversies addressed in the study, it was proven to be a very effective tool in seeking majority opinions from a group of experts. The same approach may be taken in similar studies in future.Practical implicationsThe core competence identified should be made as a minimum requirement for practitioners who wish to practise as professional BSEs. The views and comments given by the expert panel members are informative references to public policy makers.Originality/valueThis was the first ever study conducted in an attempt to identify the core competence and statutory role of BSEs in Hong Kong.

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.

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 −30 dB. 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.

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.

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 44 kWh/m 2 , 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.

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 (log R). The result confirms that “log R” 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.

Natural ventilation performance of a residential dwelling is affected by a combination of internal and external factors. External factors are often subject to constraints beyond the control of site planners and architects. Internal factors include the openings configuration, which site planners and architects are free to design the way they deem proper. However, little information is available in this regard. In this study, a case study was conducted by tracer-gas measurements at a carefully selected residential unit for Computational Fluid Dynamics (CFD) model validation. A hypothetical residential unit was formulated to represent the characteristics of typical residential units in Hong Kong. CFD simulations were performed based on the hypothetical unit to evaluate the influence of different openings configurations on natural ventilation performance using the mean age of air. Openings configuration is defined by many parameters. Among the three studied parameters, evaluation results indicate that natural ventilation performance of residential units was most affected by the relative position of the two window openings groups (i.e. bedroom windows and living room windows), followed by building orientation and doors positions. It was found that better natural ventilation performance could be achieved when the two openings groups were positioned in opposite directions or perpendicular to each other. The combined effect of the three parameters was evaluated. It was found that varying two parameters at the same time offered positive improvements in natural ventilation performance, but varying all three parameters did not result in any improvement because of the counter-effects of changes in doors positions.