Lee Siew Eang
Email Address
bdgleese@nus.edu.sg
20 results
Publication Search Results
Now showing 1 - 10 of 20
Publication An acoustic comfort model for dwellers in high-rise built environment in the tropics(2010) Alam, S.M.; Eang, L.S.; Seng, A.T.H.; Tiong, T.S.; BUILDINGResearchers in past few decades investigated on the negative evaluation of the noise environment (i.e. annoyance). Despite of an extensive and rich literature on human noise annoyance experiences, there has been very limited research effort in the investigation of acoustic comfort among residential dwellers. With the technological advancement in many aspects of our living environment in recent years, quality of life issues become prime concern. Acoustic comfort is such a key aspiration of our living environment. Acoustic comforts among high-rise dwellers, especially in the dense urban residential environment in the tropics have not been investigated yet. Since research on acoustic comfort is nascent, there is a quest for a comprehensive evaluation framework and an acoustic comfort model, developed on sound theoretical basis. The current study endeavors to expand the conceptualization of the acoustic comfort among high-rise dwellers in the tropics. A novel acoustic comfort model based on the theory of noise annoyance by Stallen (1999) is proposed in this paper.To evaluate acoustic comfort among the high-rise dwellers in the tropics, a comprehensive noise survey, using stratified sampling technique (based on major environmental noise sources), among 604 households was conceived. Evaluation of acoustic comfort in the high-rise built environment was investigated with respect to major environmental and neighbour noise sources. Perceived acoustic comfort responses were correlated to several acoustical and non-acoustical factors related the indoor noise exposure due to major environmental noise sources. Besides, subjective acoustic comfort responses were also correlated to the perceived neighbour noise and associated disturbance. Factor analysis and multiple regressions analysis of the data from the noise survey resulted in the development of an acoustic comfort model which demonstrates that acoustic comfort is dependent on the perception of noisiness and associated perceived disturbance by major environmental noise sources in the highrise residential environment in the tropics. Structural Equation Modeling (SEM) technique was then used to investigate the relationships between variables that influence acoustic comfort. Copyright © (2010) by the International Congress on Acoustics.Publication Energy utilizability concept as a retrofitting solution selection criterion for buildings(Taylor & Francis, 2017-05-25) Junjing Yang; Adrian Chong; Mattheos Santamouris; Denia Kolokotsa; Siew Eang Lee; Kwok Tham; Chandra Sekhar; David Cheong; BUILDINGPublication Air exchange efficiency of a ventilation system - A case study(1996) Sekhar, C.; Tham, K.W.; Lee, S.E.; SCHOOL OF BUILDING & REAL ESTATEThe problems associated with poor indoor air quality may in most cases be attributed to poorly designed and poorly performing ventilation systems. The problems in a mechanically air-conditioned building are compounded if the building is fairly air tight and depends on fresh air provision at the central fresh air intake in the air handling unit (AHU). The performance of such a ventilation system not only depends on the quantity of fresh air provided at the fresh air intake but the manner in which this air is distributed around the various zones in the building. The ventilation performance, characterised by the space air distribution, may be dictated by either the initial design and commissioning of the different components of the air-conditioning system, such as the AHU, ducts, diffusers, etc. or subsequent changes in the office space layout and furnishing. This paper deals with the determination of some key ventilation parameters such as the air change rate, the age of air and the air exchange efficiency, all of which lead to an insight into the performance of the ventilation system. The approach is case-study-based and the methodology involves tracer gas analysis employing the concentration decay method as a means of determining the key parameters.Publication Experimental Study on Sound Insulation of Ventilation Partitions(Hapres, 2019-12-18) Liangfen Du; Lau Siu Kit; Siew Eang Lee; Dr Lau Siu Kit; ARCHITECTURE; BUILDINGPlenum windows that ensure noise reduction and natural ventilation at the same time have been studied by many researchers. Without sacrificing the window transparency and ventilation, limited acoustical treatments could be implemented in the cavity between two glass panes to enhance noise reduction performance of plenum windows, and accordingly the sound insulation performance by plenum windows hits a bottleneck. Ventilation partition with a similar configuration to plenum windows and consisting of two opaque partition panels with staggered openings is proposed. The paper experimentally studies the sound transmission loss of six ventilation partitions with different acoustical treatments. The measurement results show that their sound transmission class (STC) ratings can be up to 21 STC points higher than that without any acoustical treatment, and the sound transmission losses are even higher than that of a closed single-layered partition at middle and high frequencies with respect to specific designs. The STC of the six ventilation partitions with acoustical treatments investigated in the present study is between STC 22 and STC 32, more than 11 STC points higher than that without any treatment.Publication The thermal effects of plants on buildings(2002) Wong, N.H.; Wong, V.L.; Chen, Y.; Lee, S.E.; Cheong, D.; Lim, G.T.; Ong, C.L.; Sia, A.; BUILDINGThe concept of rooftop gardens is introduced with the aim of reducing heat gain into a building and modifying the ambient conditions through photosynthesis and evapotranspiration of plants. Results from this study suggest that rooftop gardens can effectively cool down the immediate ambient environment by 1.5°C. Generally, the surface temperature readings collected from the rooftop garden were found to be lower than that recorded on a barren concrete rooftop. This shows that the thermal insulation of a building is improved in the presence of plants. High relative humidity (RH) at the rooftop garden was also observed due to the presence of plants. To prevent discomfort due to high humidity, adequate natural ventilation should be ensured.Publication Establishment of energy management tools for facilities managers in the tropical region(2005) Haji-Sapar, M.; Lee, S.E.; BUILDINGPurpose - To establish national energy performance benchmarks and an energy efficiency classification system for commercial office buildings from whole building to sub-systems level for building professionals including facility managers. Design/methodology/approach - Issuing of survey form and questionnaires to 16 building owners before field interview. Building physical data and systems nameplate, quantities and types were verified on site. The past 24 months electricity consumption bills were also collected from building owners. Physical environmental conditions and short-term power measurement on building systems were done to determine the level of energy consumption and performance. Research limitations/implications - The classification and benchmarking methodology developed is useful for the regions to establish their own database and tools. Practical implications - The building energy performance assessment and auditing methodology are useful to both building owner/manager and energy services companies (ESCOs) in carrying out systematic assessment and analysis on building energy characteristics. The benchmark system established will also serve as a reference to building professionals to adopt a more holistic approach in designing an energy efficient building. Useful also for building owners who are considering carrying out retrofitting works on their existing building or systems. Originality/value - The study provides detailed whole building and systems benchmarks for Singapore. The results provide an objective evaluation system of commercial office building energy performance. © Emerald Group Publishing Limited.Publication Benchmarking energy use and greenhouse gas emissions in Singapore's hotel industry(2010) Xuchao, W.; Priyadarsini, R.; Siew Eang, L.; BUILDINGHotel buildings are reported in many countries as one of the most energy intensive building sectors. Besides the pressure posed on energy supply, they also have adverse impact on the environment through greenhouse gas emissions, wastewater discharge and so on. This study was intended to shed some light on the energy and environment related issues in hotel industry. Energy consumption data and relevant information collected from hotels were subjected to rigorous statistical analysis. A regression-based benchmarking model was established, which takes into account, the difference in functional and operational features when hotels are compared with regard to their energy performance. In addition, CO2 emissions from the surveyed hotels were estimated based on a standard procedure for corporate GHG emission accounting. It was found that a hotel's carbon intensity ranking is rather sensitive to the normalizing denominator chosen. Therefore, carbon intensity estimated for the hotels must not be interpreted arbitrarily, and industry specific normalizing denominator should be sought in future studies. © 2010 Elsevier Ltd.Publication A total building performance approach to evaluating building acoustics performance(2010) Mahbub, A.S.; Kua, H.-W.; Lee, S.-E.; BUILDINGAcoustic comfort is an important consideration in the design and construction of office buildings. Since the acoustic performance of a building will affect its inhabitants psychologically, sociologically and physiologically, post-occupancy evaluations of acoustic performance are often necessary to ensure that acoustic design features are effective. Since acoustic quality is often affected by the interplay among the building's interior, structural, envelope and mechanical systems, it is critical to assess acoustic quality in an integrated manner. This article presents a detailed acoustic evaluation of a three-storeyed office building by adopting a total building performance (TBP) approach. Through plan/archive analysis, expert walkthrough, objective acoustic measurements and analysis, the existing acoustic problems are identified. Subjective views of occupants regarding acoustic quality in the office and warehouse spaces are also sought. It was found that both objective and subjective data support each other. By understanding how these problems are caused by the interactions among the different building systems, specific solutions were proposed. In summary, this work highlights the usefulness of using a TBP concept to diagnose the acoustic quality of a multi-storeyed office building in an integrated manner. This project is motivated by an effort to promote workplace comfort and sustainability within the framework of corporate social responsibility. © 2010 Earthscan.Publication Vertical profile of train noise and indoor noise in high-rise residential environment(2009) Alam, S.M.; Lee, S.E.; Johnny, W.L.H.; BUILDINGNoise from elevated Mass Rapid Transit (MRT) train is a source of annoyance to the high-rise residents in land-scarce Singapore. Due to high density living in Singapore, residential buildings are in close proximity of railway tracks. Due to tropical climate, the windows are left open for provision of natural ventilation. This requirement in buildings reduces the aural comfort by exposing residents to relatively high noise levels in the apartments concerned. For provision of acoustical comfort to the high-rise dwellers, a scientific and reliable approach is vital in characterizing noise propagation from MRT and establishment of façade acoustical requirements. Two sixteen-storey residential buildings were investigated with MRT noise measurements conducted on each level of the buildings. Predicted results from software simulation were validated with field measured data. This study observes that MRT noise increases by 6.3 and 5.7 dBA at a height of 26.7m with the increase in building height where the buildings are located at 28m and 33m away from the track respectively. Measured sound insulation of eight different types of façades show that the opening of a window panel reduces façade performance up to 27 dBA. The derived indoor noise level is finally evaluated with the acceptable indoor noise level established from a comprehensive noise survey.Publication Building energy consumption raw data forecasting using data cleaning and deep recurrent neural networks(MDPI AG, 2019) Yang, J.; Tan, K.K.; Santamouris, M.; Lee, S.E.; BUILDINGWith the rising focus on building energy big data analysis, there lacks a framework for raw data preprocessing to answer the question of how to handle the missing data in the raw data set. This study presents a methodology and framework for building energy consumption raw data forecasting. A case building is used to forecast the energy consumption by using deep recurrent neural networks. Four different methodologies to impute missing data in the raw data set are compared and implemented. The question of sensitivity of gap size and available data percentage on the imputation accuracy was tested. The cleaned data were then used for building energy forecasting. While the existing studies explored only the use of small recurrent networks of 2 layers and less, the question of whether a deep network of more than 2 layers would be performing better for building energy consumption forecasting should be explored. In addition, the problem of overfitting has been cited as a significant problem in using deep networks. In this study, the deep recurrent neural network is then used to explore the use of deeper networks and their regularization in the context of an energy load forecasting task. The results show a mean absolute error of 2.1 can be achieved through the 2*32 gated neural network model. In applying regularization methods to overcome model overfitting, the study found that weights regularization did indeed delay the onset of overfitting. � 2019 by the authors.