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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.

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 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.

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...

Limonin was found be the main cause of bitterness in ponkan juice. Adsorption debittering of ponkan juice was carried out with macroporous adsorbent resins of EXA-45 and LX-900. Effects of adsorbent dosage, initial limonin concentration, and adsorption time on debittering efficiency were investigated. Data on equilibrium were fitted with Langmuir, Freundlich, and Temkin models. It was observed that the Temkin equation was the best fit for limonin adsorption by EXA-45 (R2 = 0.9641), while the Freundlich equation was the best fit by LX-900 (R2 = 0.9930). EXA-45 presented higher adsorption capacity and faster adsorption rate than LX-900. The kinetic equations were examined and the results showed that the adsorptions of limonin on EXA-45 and LX-900 were fitted to pseudo second-order kinetic model with R2 of 0.9936 and 0.9922, respectively. This study indicated that EXA-45 and LX-900 exhibited potential application for removal of limonin from ponkan juice, and the former resin may be better.

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.

Supercritical carbon dioxide (SC-CO2) extraction of whole fruit oil from Gardenia jasminoides Ellis was performed. The effect of extraction pressure, temperature and CO2 flow rate on the oil yield was investigated by response surface methodology (RSM). The results showed that experimental data had a good fit to the proposed model (R 2 = 0.938). Extraction pressure, CO2 flow rate, the quadratics of pressure, and the interaction between pressure and flow rate showed significant effects on the oil yield (p