W.L. Lee

On the study of the credit-weighting scale in a building environmental assessment scheme

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.

Regulatory and voluntary approaches for enhancing energy efficiencies of buildings in Hong Kong

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%.

Energy saving by realistic design data for commercial buildings in Hong Kong

Oversized equipment is one of the key factors for poor energy performance of commercial buildings in Hong Kong. Similar situations exist also in many buildings in different parts of the world. The use of realistic design criteria has been identified as an effective method to reduce the equipment oversizing problem. A set of realistic design criteria for lighting power density, occupation density, and appliances load-intensity for various types of premises have been established based on data obtained in walk-through surveys of energy end-uses in 31 Hong Kong office buildings. Potential electricity savings through the use of realistic design criteria were estimated to be 6-22% of the electricity consumption of Hong Kong, which corresponds to an annual cost of HK

Assessing the cost effectiveness of an environmental assessment scheme

12.2-44.7 billion.

Framework for formulating a performance-based incentive-rebate scale for the demand-side-energy management scheme for commercial buildings in Hong Kong

Abstract This paper examines the key issues involved in evaluating cost and benefits of various accredited criteria of an environmental assessment scheme in Hong Kong. Economic benefit–cost ratios have been developed for various criteria to help the developers and designers to identify the economic impact and cost effectiveness of the accredited criteria. Results of this analysis reveal that the economic benefit–cost ratios vary among different credits, and 24 out of total 56 credits could provide potential economic benefit for the developers and designers. Accordingly, a decision strategy for prioritising the criteria selection has been developed for the developers and designers. Besides, the use of economic benefit–cost ratios for revising the weighting scale within the performance-specific criteria is discussed.

Site verification and modeling of desiccant-based system as an alternative to conventional air-conditioning systems for wet markets

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.

A strategy for prioritising interactive measures for enhancing energy efficiency of air-conditioned buildings

n Abstractn n 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 10.3xa0L/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 20xa0L/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.n n

Developing a simplified parameter for assessing view obstruction in high-rise high-density urban environment

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.

Monitoring the competitiveness in the supply of low-voltage switchboards

n Abstractn n View is a key factor that influences property price. Previous studies represent view either by simple pictorial description of a scene, or by rather sophisticated mathematical methods. Both hinder proper allocation of a premium for different view obstruction levels for high-rise high-density urban environments. View obstruction level and the applicable premium are useful information for stakeholders of the property market for making optimum decisions. Accordingly, there is a need to develop a simple parameter for assessing view obstruction level. While view is difficult to define, reference is made to law cases which often settle view disputes by the extent of daylight obstruction. Shading mask is typically used to assess availability of daylight outside a residential unit and hence is an ideal parameter for assessing view obstruction. Computation of shading mask values (SMK) is a very complex task that needs meticulous site surveys, 3D drafting skills, and computer simulations. They are too effort intensive for stakeholders. This paper summarizes the relevant considerations and the case studies conducted to establish the average angle of unobstructed sky (θ) as a simple parameter to represent mean SMK for assessing view obstruction. Correlation analysis of mean SMK of 708 case study residential units determined by the detailed computer simulation method and the corresponding angle of unobstructed sky showed that the latter can be used to assess view obstruction adequately close to simulation predictions. Given average angle of unobstructed sky can easily be determined based on the geometrical primitives of a residential unit, this can enable future allocation of a premium for different view obstruction levels for stakeholders.n n

Development of price models for architectural and environmental quality for residential developments in Hong Kong

This paper reports an innovative, scientific and yet practicable approach developed in assisting a large-scale high-rise residential building developer in Hong Kong for monitoring the competitiveness in the switchboard supply to her development projects. In this study, a pricing indicator was developed for monitoring whether the pricing levels charged to developer had attained a competitive level. Our results revealed that the pricing level charged to the developed was far from competitive, and the high cost was contributed by inadequate competitiveness in the switchboard supply as a result of the practice of including only a limited number of suppliers on the pre-qualification list. By relaxing the pre-qualification requirements, the pricing level dropped to a very competitive level after two additional suppliers being included on the list.