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Purpose – This study aims to develop a prototype for measuring the carbon emissions arising from the utilization of electrical appliances in a typical Hong Kong family in Kowloon District. Design/methodology/approach – To estimate carbon emission coefficients of energy consumption, the US building energy database books are referred to, which include home appliances’ energy end-use expenditure splits and energy end-use carbon splits. Due to differences in climate, geography and culture, the estimation equations are refined with assumptions and constraints based on the context of Hong Kong. Findings – By calculating the amount of carbon emissions from different electrical appliances, including space cooling, water heating, lighting, refrigeration, wet cleaning and cooking, it is estimated that the carbon emissions from major home electrical appliances in Hong Kong’s residential building sector is 1,805,397 metric tons. According to the findings of this study, by adopting the energy-saving guidelines for space coolers, refrigerators, water heaters and washing machines, carbon emissions in Hong Kong’s residential building sector can be reduced by 155,443 metric tons, or by 8.6 per cent of the current emission. Research limitations/implications – Due to limited resources, the case study does not cover residential units in other districts of Hong Kong, including the Hong Kong Island and the New Territories. In addition, relevant institutional and financing costs of implementing the proposed practices such as increasing the air-conditioning temperature and upgrading the lighting system should be further considered. Future research will be extended to the wider territory of Hong Kong and to obtain more cases for analysis. Originality/value – This paper provides a microscopic perspective on investigating the carbon emissions associated with energy consumption from major home electrical appliances in Hong Kong’s residential buildings. By unveiling the interaction between energy consumption and carbon emission, we formulate measures and strategies for implementing a cost reduction and carbon saving scheme of Hong Kong’s residential buildings, which is in line with government’s guidelines on green buildings. [ABSTRACT FROM AUTHOR]

Abstract: Building cooling load prediction is one of the key factors in the success of energy-saving measures. Many computational models available in the industry today have been developed from either forward or inverse modeling approaches. However, most of these models require extensive computer resources and involve lengthy computation. This paper discusses the use of data-driven intelligent approaches, a probabilistic entropy-based neural (PENN) model to predict the cooling load of a building. Although it is common knowledge that the presence and activity of building occupants have a significant impact on the required cooling load of buildings, practices currently adopted in modeling the presence and activity of people in buildings do not reflect the complexity of the impact occupants have on building cooling load. In contrast to previous artificial neural network (ANN) models, most of which employ a fixed schedule or historic load data to represent building occupancy in simulating building cooling load, this paper introduces two input parameters, dynamic occupancy area and rate and uses it to mimic building cooling load. The training samples used include weather data obtained from the Hong Kong Observatory and building-related data acquired from an existing grade A mega office buildings in Hong Kong with tenants including many multi-national financial companies that require 24-h air conditioning seven days a week. The dynamic changes that occur in the occupancy of these buildings therefore make it very difficult to forecast building cooling load by means of a fixed time schedule. The performance of simulation results demonstrate that building occupancy data play a critical role in building cooling load prediction and that their use significantly improves the predictive accuracy of cooling load models. [Copyright &y& Elsevier]

Window glazing affects much the indoor environment and the energy use in buildings. While double glazing has better thermal performance than single glazing, the airflow window options carry additional advantage of directly removing the absorbed solar energy in glass panes. This paper reports an experimental study in Hong Kong in evaluating the thermal/energy performance of the above-mentioned glazing systems. A new approach of using numerical simulation technique to improve the quality of experimental analysis was introduced. Our findings show that the natural-ventilated glazing system has a better thermal performance than the double-glazing system since the latter received 13.6% more convective heat gain. The main advantage of the exhaust-ventilated glazing system lies in the decrease of convective heat transfer to 34.3% of the double glazing, and 19.4% of the single-glazing types. The results showed that the ventilated glazing schemes in association with daylight utilization could lead to substantial electricity savings in the office environment. Copyright © 2008 John Wiley & Sons, Ltd. [ABSTRACT FROM AUTHOR]

Despite an increased awareness about energy conservation in the past decade, the energy consumed for water heating has increased by 7% from 2008 (17%) to 2018 (24%) in Hong Kong. A literature review on existing energy-saving technologies during showering showed that occupants' behavior significantly impacted energy consumption. However, the exact relationship between them was not yet fully understood. Therefore, this study developed a mathematical energy consumption model to investigate the relationship between occupants' behavior and energy consumption during showering. This relationship identified an effective energy-saving strategy in the shower without scarifying occupants' thermal comfort. The main variables that influence energy consumption and thermal comfort in bathrooms namely air temperature, water temperature, ventilation rate, and water flow rate, were considered. It was found that among them, water flow rate and ventilation rate are the most and least influential variables, respectively, in energy saving. Therefore, the ventilation rate was suggested to be at least 0.03 kg·s−1, and the water flow rate was meant to be lower than 0.15 kg·s−1 (based on related requirements). These findings could help residential occupants and facility managers determine the optimal showering settings for thermal comfort, energy consumption, and environmental effects. [ABSTRACT FROM AUTHOR]

• A POE-integrated simulation method is proposed to address energy occupant behavior. • Opening windows and operating AC were found to co-exist which affects simulation accuracy. • The new method improves energy simulation accuracy by 14% for domestic areas. • The method improves energy simulation accuracy by 16% for total building areas. Occupant behavior plays a critical role in building energy consumption, particularly in residential buildings. However, occupant behavior is complicated and varies significantly from case to case. Also, energy modeling of high-rise buildings is far less explored than that of low- or medium-rise buildings. This paper aims to improve accuracy in building energy simulation by utilizing Post Occupancy Evaluation (POE) data to calibrate energy model. Drawing on a review of the literature of occupant behavior and building energy modeling, the paper provides a calibration method of integrating POE data into an energy model, which is demonstrated using a real-life typical 40-storey residential building in Hong Kong. The developed method addresses seven updated input parameters, namely, schedule, devices, air-conditioners, windows, lights, domestic hot water, and cooking. By comparing the two energy modeling processes, i.e. with and without POE input, and their resultant estimated energy consumption, the paper quantifies the impact of occupant behavior on building energy consumption. Annual metered data together with energy bills obtained from the POE were utilized to validate the models. The results show that the use of the developed POE-integrated method helped to improve accuracy in energy consumption prediction by 14% for the total building floor area and by 16% for the total residential area. From examining the impacts of the seven input parameters, the paper reveals the key energy use sensitive occupant behaviors within high-rise residential buildings in Hong Kong. These include: the number of residents in each unit; adoption of window type and split type of air-conditioners; window and air condition operation modes; cooking time on weekdays and weekends; and time spent on hot water showering. The developed method can assist building designers and services engineers to estimate building energy use more accurately and provides a scenario analysis tool for clients and facility managers to develop effective energy conservation strategies. [ABSTRACT FROM AUTHOR]

The estimation of solar heat gain via vertical fenestration is important in energy-efficient building design and operation especially for subtropical Hong Kong. Being one of the most populated cities in the world, buildings in Hong Kong tend to be densely constructed. In this regard, the shading effect of surrounding buildings could significantly limit solar radiation from the sun and sky to the window while certain amount of solar radiation would be reflected from the opposite façades. This paper presents a calculation approach to compute solar radiation on obstructed fenestration for both overcast and non-overcast skies. Performance of the proposed method is evaluated by comparing with simulated results of a sophisticated lighting program and field measurements. The findings are essential for the assessment of both active and passive building energy saving techniques including shading and building integrated photovoltaic systems in metropolitan environment. [ABSTRACT FROM AUTHOR]

Abstract: This paper presents a new strategy using a limited number of sensors for demand-controlled ventilation (DCV) of multi-zone office buildings. The conventional CO2-based demand-controlled ventilation strategy for multi-zone offices requires CO2 sensors and supply airflow meters being installed in all zones. However, in many practical cases, CO2 sensors might not be available or not necessary. To control the outdoor airflow based on actual occupancy variations in such cases, a DCV strategy with two implementing schemes is developed for different sensor availabilities. The first scheme is used for the situation when CO2 sensors in individual zones are not available but the airflow meters for individual zones are installed. The second scheme is used for the conditions when CO2 sensors and airflow meters in individual zones are not available. These two schemes use two different approaches to estimate the outdoor airflow fraction of the critical zone approximately. Both schemes only require the CO2 sensor in the main return air to dynamically detect the total occupancy number. The developed strategy is implemented and validated in a high-rise office building in Hong Kong. The site test results show that the strategy can achieve significant energy saving while maintaining acceptable IAQ in the situations where only limited sensors are available. [Copyright &y& Elsevier]

Abstract: In Hong Kong, conventional air-conditioning (AC) systems cause a high energy consumption and poor indoor thermal comfort. This paper investigated the AC load profiles of three typical local commercial buildings, i.e. office, hotel and retail, and examined the energy consumption of liquid desiccant cooling system (LDCS) for these buildings. Simulation results showed that the cooling load contributed to more than 98% of total annual load, with high latent load proportion from March to September. The high reheating ratio, i.e. from 60% to 90%, is found to be the main reason for the poor thermal comfort. Therefore, the LDCS which could handle sensible and latent loads separately was proposed. However, the electricity-driven LDCS was found not suitable for local commercial buildings. significant energy saving could be achieved by the solar-assisted LDCS system with thermal storage, when the installation area for solar collectors is larger than the minimum required one, i.e. 9.7m2/(kWm−2) for office and 12.7m2/(kWm−2) for hotel buildings. Energy saving of different system types with different installation areas was also studied. The solar-assisted LDCS shows more energy saving in winter but less in summer. Results and conclusions can be useful for researchers and local engineers. [Copyright &y& Elsevier]

Abstract: Energy consumption by passenger transport in Hong Kong increased rapidly in the past decades and in 2008 it accounted for 19.7% of total energy use. Improving energy efficiency has been widely regarded as an effective way for reducing energy use in the transport sector. However, the expected energy savings from energy efficiency improvement are likely to be discounted due to the existence of rebound effect. This paper employs econometric models to estimate the direct rebound effect for private passenger transport in Hong Kong. We find that the magnitudes of the direct rebound effect are respectively 45% and 35% for 1993–2009 and 2002–2009, which indicates that there was a declining trend in the direct rebound effect for passenger transport over time. It also indicates that the direct rebound effect needs to be taken into consideration in assessing the impact of energy efficiency measures on reducing energy use in Hong Kong. [Copyright &y& Elsevier]

Abstract: The shading-type BIPV claddings can act as power generators as well as external shading devices and insulation panels. There is little available information about the impacts of orientations and inclinations on the combined energy effects of the shading-type BIPV claddings, including the power output of PV modules, the cooling load reduction of windows and concrete walls. It is worth studying the effects of different shading-type BIPV cladding designs on the total energy saving in order to maximize the system’s energy performance. By considering the meteorological conditions in Hong Kong, the energy effect of the shading-type BIPV claddings with different surface azimuth angles, in terms of electricity generation and cooling energy consumption reduction is analyzed in this paper. Based on the investigations, the optimum design of the shading-type BIPV claddings for different orientations can be achieved. [Copyright &y& Elsevier]

This paper firstly presents a case study on analyzing the electrical load profiles recorded in a Hong Kong hotel over a period of 12 months to examine the potential energy saving opportunities (ESOs) in its building services installations. The case study is followed by a report of the survey results of energy and water use in 36 quality hotels in Hong Kong. Finally, a regression analysis where the surveyed energy and water use data were correlated to a number of hotel background or operational parameters to search for suitable energy and water use performance explanatory indicators is presented. The survey results depict a diversified energy and water use situation in Hong Kong’s hotels, but the regression analysis indicates that, while some of the correlations obtained are weak, there do exist a few strong energy and water explanatory indicators. [Copyright &y& Elsevier]

This paper estimates the quantity of pollutants produced by the hotel industry through its electricity consumption. A survey of 17 hotels in Hong Kong was carried out to collect 3 years of energy consumption data. Regression analysis indicated that gross floor area was a major and statistically accepted factor in explaining the electricity consumption in hotels. It was found that the average electricity consumption was about 342 kW h/m2/year. Then, based on some established pollutant emission factors of coal and natural gas, the amount of sulphur dioxide, nitrogen dioxides, carbon dioxides and particulates created by the hotel industry''s electricity usage during a 10-year period from 1988 to 1997 was estimated. The study further predicts the increase in these amounts in 1998–2003 accompanying the rise in the number of hotel properties. The findings indicate that the existing green measures and devices are inadequate to cope with the increase in pollution emission in the near future. We believe that the hotel industry should adopt a more proactive approach to reduce electricity usage and propose the inclusion of environmental reporting in trade journals. [Copyright &y& Elsevier]

This paper reports on a study of energy use in 16 quality hotels in Hong Kong. An overview of energy use in these hotels is firstly presented, and this is followed by a detailed analysis of energy use in one of the 16 hotels. The overview indicates that the energy use situation in hotels in Hong Kong is very much diversified. The total energy use in a hotel is dominated by electricity, with the greatest portion for air conditioning because of sub-tropical climate. A detailed multiple variable regression analysis indicated that a number of hotel operating parameters as well as climatic condition can affect electricity, diesel and gas use in a hotel building. In order to achieve both operating cost saving and environmental protection, it is recommended that an energy management programme be established, and key elements of such a programme based on the experience of implementing energy conservation strategies in hotels in Hong Kong are highlighted. [Copyright &y& Elsevier]

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

This article presents the test and evaluation of energy saving potentials of complex building central chilling systems using genetic algorithm (GA). The evaluation was conducted based on a simulated virtual system representing the actual complex central chilling system in a super high-rise building in Hong Kong. GA was used as the optimisation tool to search for globally optimal control settings. The simulated virtual system was used as the test platform and acted as the performance predictor in estimating the overall system performance and responses to the changes of control settings. The test results show that about 4.54—5.06% daily energy in the system studied can be saved by using optimal control settings, as compared to that using the conventional control settings. The results also show that the evaluation process by using the simulated virtual system and the GA optimiser is time costly due to strong dynamic effects of the simulated virtual system and the optimisation principle of GA.Practical applications: This article presents an approach for evaluating energy saving potentials of complex central chilling systems using GA. This approach can be used to identify maximum energy saving potentials in air-conditioning systems by optimising the major control variables simultaneously. The results can be used to guide the development of advanced control and optimisation strategies suitable for practical applications. [ABSTRACT FROM PUBLISHER]

Since the energy crisis in the 1970s, the government and policymakers have endeavoured to promote energy conservation policy on sustainable building designs and operations. Various benchmarks of building energy consumption were developed. Unfortunately, the complicated benchmarking models would impose difficulties in general adaptation. This study proposes a simple sustainability benchmark using a 5-star rating system for electricity and fuel gas consumption in residential buildings. With this system, the least sustainable households, i.e. the top 10% of the survey samples in consumption, would be awarded with the lowest sustainability rating of '1 star', while the most sustainable households (i.e. the bottom 10%) would be awarded with the highest rating of '5 stars'. This simple model would be useful for identifying the extreme cases of energy consumption and promoting the policy on sustainable building practices without inclusive measurements. Practical application: A simple sustainability benchmark model using a 5-star rating system for electricity and fuel gas consumption in residential buildings is proposed. This model would be useful for promoting the policy on sustainable building practices without inclusive measurements by identifying the extreme cases of consumption. [ABSTRACT FROM AUTHOR]

In this experimental study, the performance of ventilated double-pane glazing integrated with semitransparent solar cells under the subtropical climate of Hong Kong has been investigated. The effects of a photovoltaic (PV) ventilated glazing system on the built environment - including heat and light transmission, thermal and visual comfort, and electricity generation - were analyzed and discussed. While the energy saving potential of PV glazing on air-conditioning demands was found promising, the same on daylight utilization was much inferior to the absorptive glazing applications. The purpose of the study was to gain experience on better use of the semi-transparent PV ventilated glazing technology, and on the energy/cost saving potential of some innovative arrangements. [ABSTRACT FROM AUTHOR]

There are different ventilation control methods for outdoor air quantity in air-conditioned spaces to reduce the energy consumed in cooling the outdoor air. Demand controlled ventilation (DCV) is an important strategy to control the outdoor air quantity. However, the current practice in DCV systems creates several problems for air-conditioned office buildings. Although metabolic carbon dioxide (CO2) concentration is mainly used as a surrogate indicator for ventilation adequacy, the conventional DCV system does not seriously consider the placement location of the CO2 sensor, and it does not take into account the adverse effects of the consequential increase in pollutant concentrations in the indoor space when the fresh airflow rate is reduced. In this study, a long period of subjective and objective measurements were conducted in an occupied office to examine its suitability for conversion to a new demand controlled ventilation system (nDCV). After the feasibility investigation, an nDCV system was developed to optimize the energy consumed for outdoor air ventilation while providing the desirable thermal comfort and indoor air quality. The true optimization of this nDCV is achieved by a new concept of the optimized indoor air quality window which determines the most representative locations for the indicator sensors. A minimum ventilation rate is determined by a calibration procedure for the pollutant inventory of a building, taking into account the infiltration characteristics. Radon gas, which is a notorious carcinogenic indoor pollutant, is used as a reference to determine the minimum fresh airflow rate. The findings show that this nDCV system reduced 16% of fresh air cooling energy consumption without jeopardizing the thermal comfort and indoor air quality. [ABSTRACT FROM AUTHOR]