No abstract

The quality of buildings, including their performance in a range of indoor environmental attributes, is influential to the living quality of habitants. Many studies on appropriate importance weights for the attributes have been reported but few embraced both human perception of the importance of such attributes and the related performance of buildings.Focusing on typical public and private high-rise residential buildings in Hong Kong, users' perceived importance of four key attributes, namely thermal comfort, air cleanliness, odour and noise, and their perceived performance of the buildings in these attributes were studied.Perceptions collected from 563 respondents were processed through an analytical hierarchy process to generate importance weights for the attributes. Correlation analyses corroborate that perceived importance may vary among buildings of different types and between residents and visitors. Thermal comfort was perceived by the vast majority as the most important.Using a performance-importance plot, it is shown how the gaps between perceived performance and perceived importance can be identified. The results can help determine the areas for improvement in new building designs and facilitate prioritization of limited resources for upgrading building performance.

Recognition of the importance of the quality of the indoor environment (IEQ) to health, comfort and productivity of building end users has produced increasing numbers of voluntary schemes whose assessment embraces a wide spectrum of environmental attributes. Studies which aim to derive appropriate weighting factors for these attributes through soliciting the perceived importance from experts are abundant. This article reports the findings of a study which, based on face-to-face interviews with 548 end users and 66 building professionals, processed their perceived importance of IEQ using the analytical hierarchy process (AHP). Attributes included were thermal comfort, air cleanliness, odor and noise associated with the air conditioning system of typical commercial buildings. Correlation analysis of the ranking results of the AHP weights revealed the difference in perceived importance of the attributes according to gender of the respondents. Other factors also found to have influence on the perceived importance of the IEQ were whether the respondents were professionals or other end users and the reason for them working or visiting the buildings and the duration of their stay. These all varied with psychophysical factors such as personal experiences, needs and expectations. Further work is needed to study whether the weighting factors should be derived from the perceptions of experts, end users, or a balance between the two.

PurposeThe recession in the late 1990s in Hong Kong has triggered many commercial building owners to cut operation and maintenance (O&M) cost via outsourcing. The purpose of this paper is to investigate the dominant expenditure on O&M service and examine the relation between extent of outsourcing and rental income of the buildings.Design/methodology/approachExperienced O&M practitioners were interviewed to collect both quantitative and qualitative data of the commercial buildings they looked after. The in‐house and outsourced O&M costs, air‐conditioning energy costs, rental incomes, and management and air‐conditioning fees for the buildings were analysed.FindingsThe total air‐conditioning O&M cost is the principal cost item, with the energy cost being the dominant element. The analysis reveals that the extent of outsourcing bore little correlation with the air‐conditioning O&M cost and the rental income.Research limitations/implicationsFurther work may take a similar approach to identify the extent and effect of outsourcing other kinds of services that underpin the core business of an organisation.Practical implicationsVarying the extent of outsourcing O&M service was found to be unpromising for enhancing rental performance or cutting O&M expenditure. This is an important point that the building managers should address when considering whether to go for outsourcing.Originality/valueThe findings imply that in the building O&M service industry, it would be more economical to outsource or undertake in‐house the vast majority of O&M work. The focus for cost minimization should be to improve building energy performance rather than reducing labour resources through outsourcing.

Building occupants can enjoy a healthy and comfortable indoor environment and use less cooling energy if sufficient natural ventilation is available in their dwellings. Assessing the natural ventilation performance of building designs requires modelling of the external wind environment, the natural ventilation rate and the thermal environment in individual rooms, and reduction in the use of air-conditioning equipment. These are complicated processes. A practical approach for assessing the natural ventilation performance of residential building designs is presented in this paper. The method includes prediction of wind pressures upon window openings in the building façade by computational fluid dynamics simulation, natural ventilation rate prediction using a flow network simulation model, and indoor free-float temperature and air-conditioning energy-use predictions using a building heat transfer and an air-conditioner performance simulation programme. Additionally, the method includes a simplified statistical approach to deal with the random variations in the speed and direction of the wind. This method has been applied to assess the natural ventilation performance of a standard public housing block design widely used in Hong Kong, taking into account when the wind wing walls were incorporated into the building façade and when the separation distances among the building blocks were widened by 25% and 50%.