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Abstract: The growing concerns over the environmental impacts of buildings have led to increasing demands for more environmental friendly buildings and building materials. Hitherto, there are not any comprehensive studies that show the overall environmental impact profiles of building materials and building services components for buildings. This paper intends to bridge this gap by reporting overall lifecycle environmental profiles of buildings as well as the ranking orders of environmental impacts of all the building materials and building services materials and components for commercial buildings. Twenty-five commercial buildings in Hong Kong, which include three Grade A office buildings, four Grade B office buildings, one Grade C office buildings, four retail centers and three hotels, have been selected for our study. Based upon these collected samples, no statistical differences were found in the average lifecycle environmental impacts for different building types despite some minor variations were detected. Subsequently, 10 types of building materials and 10 types of building services components have been identified for their significant lifecycle environmental impacts on commercial buildings. Among all, concrete, reinforcement bar, copper power cables, and copper busbars were ranked to be the four most significant materials or components to the total lifecycle environmental impacts. These should form the major targets for improvements in environmental performance of commercial buildings. [Copyright &y& Elsevier]

Abstract: Economic principles have been applied to elicit the conditions under which there will be benefit to power companies in offering rebates to consumers to encourage them to adopt energy saving measures. The analysis also provides an answer to how rebate rate should be determined to maximise social benefit. However, the analysis of the rebate-based demand side management (DSM) programmes launched by the two power companies in Hong Kong in the year 2000 showed that the prerequisite conditions that would permit the power companies to derive benefits from the programmes were unlikely to exist. This suggests that use of this economic instrument for promoting energy efficiency requires governmental influence; it will not emerge solely as a commercial decision of the power companies in Hong Kong. [Copyright &y& Elsevier]

This paper inquires into whether overall thermal transfer value (OTTV) is an appropriate building envelope energy performance index for use in regulatory control. First, a historical review of the use of OTTV in American Society of Heating, Refrigerating and Air-conditioning Engineers (ASHRAE) Standard 90 is presented, followed by a review of more recent work on its further development and application. The major deficiencies of OTTV are then discussed, and simulation study results meant to highlight the impacts of such deficiencies are presented. The study embraced air-conditioned office buildings and air-conditioned high-rise residential buildings in Hong Kong. Results of this study clearly show that the OTTV calculated with the use of pre-calculated coefficients may not truly reflect the thermal performance of a building envelope. Therefore, a second thought should be given to the use of OTTV in building energy codes. [Copyright &y& Elsevier]

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

Surveys have been conducted to obtain information about the building design and energy end-use characteristics of high-rise residential buildings in Hong Kong. The building design characteristics data obtained include the floor areas of residential flats, the ratios of the areas of bedrooms and living and dining rooms to the total flat area, the window-to-wall area ratios, the types of fenestration, and the external-shading devices in facades of residential buildings. The energy data obtained include the household energy and electricity uses, and the type and quantity of appliances used in residential units. The saturation rates of various domestic appliances and their utilisation patterns, and the annual energy use for air-conditioning and water heating in residential units in Hong Kong have been estimated based on the collected data. [Copyright &y& Elsevier]

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

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]

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

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

• The performances of physical and Bayesian approach for sensor bias detection were evaluated. • The superior performance of Bayesian model in handling cases with incomplete data was explained. • Effects of the prior belief with or without being updated were discussed. Together with the thermo-physical relationships among the flow rates and temperatures of water in a piping system, the Bayesian method was employed to develop a model for detection and evaluation of biases of water flow and temperature sensors in a central chiller plant. The model can handle biases of multiple sensors occurring simultaneously and can remain functional when the coverage of the available measurements is incomplete. A series of case studies was done to verify the performance of the model and for comparison with the conventional method that is based solely on the thermo-physical relationships. The cases studied involved the use of synthetic plant operating data and actual operating records of an existing chiller plant. In this paper, the theoretical basis of the model is outlined, and explanations are given for the superior performance of the Bayesian method in handling cases with data that cannot fully cover the required range of operating chiller patterns. Results of the cases unveiled the effects of the prior belief with or without being updated during the estimation process, and of biases occurring in steps at the same time and at different times, as well as those that would increase with time. Furthermore, the case studies showed that the Bayesian method was able to detect sensor biases of a magnitude of ± 0.5 °C or lower. [ABSTRACT FROM AUTHOR]

Highlights: [•] A method to evaluate the probability of saving shortfall for energy performance contracting projects is proposed. [•] Two calibrated building energy models are developed using EnergyPlus. [•] The influential parameters affecting the chiller plant energy use are identified. [•] The probability distributions functions are developed using empirical data. [•] A case study is analysed to illustrate the methodology. [Copyright &y& Elsevier]

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