T.M. Leung

An analysis on the HVAC maintenance contractors selection process

The growing importance of the maintenance industry renews the interest of both practioners and academia working in the maintenance field. In the past or even now, most of the maintenance work contractors are selected purely on basis of the lowest tender prices, even though they are required to be undergone the pre-qualification process. However, it is increasingly admitted that the practice of awarding tenders on a basis of low tender price eventually would lead to the ultimate quality problems. In consequence, there is a serious outcry in the public sector demanding a revolution in the current tender awarding system. Accordingly, this study intends to test how different managers actually choose maintenance contractors. This in turn would lead us to focus on the identification of the major selection attributes, and the trade-off weightings among attributes during the selection process. In this study, the identification and the trade-off weightings for different contractors selection attributes are revealed by conjoint analysis. Meanwhile, a Likert scale rating is also used to reveal whether there are disparities between the relative perceived importance and the relative weights in actual selection in the contractors selection attributes. Our results found that there are some consistencies in the relative perceived importance and the relative weights in actual contractor selection. On the other hand, our results also reveal that the contractors should put more effort in improving their company reputation in order to win the maintenance contracts.

Willingness to pay for improved environmental performance of the building envelope of office buildings in Hong Kong

This study examines the amount of money that designers and developers are willing to pay to improve different aspects of the environmental performance of exterior envelopes by using office buildings in Hong Kong as an example. A method modified from the averting expenditure approach was applied to 16 office buildings built or tendered between 1999 and 2001. Our results show that the designers and developers considered the provision of an appropriate sensation index of outdoor connection (or window to wall ratio) for building envelopes was far more important than improvement of the environmental performance when the interiors of their buildings were open to a view showing them surrounded by other office buildings. Improvement in thermal performance of building envelopes would be considered only if an appropriate window-to-wall ratio had been fixed. Application of the method has successfully shown the amount an individual developer will invest and a designer’s willingness to pay to improve the performance of a building envelope. The methodology should be able to be extended to other building elements, components or systems after some modifications.

The effects of neighborhood views containing multiple environmental features on road traffic noise perception at dwellings

The importance of non-acoustical factors including the type of visual environment on human noise perception becomes increasingly recognized. In order to reveal the relationships between long-term noise annoyance and different types of neighborhood views, 2033 questionnaire responses were collected for studying the effect of perceptions of different combinations of views of sea, urban river, greenery, and/or noise barrier on the annoyance responses from residents living in high-rise apartments in Hong Kong. The collected responses were employed to formulate a multivariate model to predict the probability of invoking a high annoyance response from residents. Results showed that views of sea, urban river, or greenery could lower the probability, while views of noise barrier could increase the probability. Views of greenery had a stronger noise moderation capability than views of sea or urban river. The presence of an interaction effect between views of water and views of noise barrier exerted a negative influence on the noise annoyance moderation capability. The probability due to exposure to an environment containing views of noise barriers and urban rivers would be even higher than that due to exposure to an environment containing views of noise barriers alone.

Importance of Being Connected to the Outside in the Workplace

This study examines the relative importance of environmental attributes and sensation of outdoor connection in the design of windows for a workplace by focusing on a sample of practicing building designers in Hong Kong. Discrete choice analysis using a combined visual image and textual and numerical figures was employed to reveal the importance being used by the designers in their evaluation of four performance attributes. Our analysis reveals that the designers placed equal importance on sensation of outdoor connection and thermal performance in window design for the workplace when the interiors of their buildings were open to a view surrounded by other office buildings. On the contrary, daylighting and acoustic performances were not considered to be important in their decision making process. This implies that the designers in Hong Kong had already started to translate their environmental awareness into appropriate design decisions by factoring in thermal energy saving as one of the important considerations for the window designs for the workplace.