Showing papers by "Chuck Wah Yu published in 2013"

The role of water content in triboelectric charging of wind-blown sand

Abstract: Triboelectric charging is common in desert sandstorms and dust devils on Earth; however, it remains poorly understood. Here we show a charging mechanism of sands with the adsorbed water on micro-porous surface in wind-blown sand based on the fact that water content is universal but usually a minor component in most particle systems. The triboelectric charging could be resulted due to the different mobility of H+/OH− between the contacting sands with a temperature difference. Computational fluid dynamics (CFD) and discrete element method (DEM) were used to demonstrate the dynamics of the sand charging. The numerically simulated charge-to-mass ratios of sands and electric field strength established in wind tunnel agreed well with the experimental data. The charging mechanism could provide an explanation for the charging process of all identical granular systems with water content, including Martian dust devils, wind-blown snow, even powder electrification in industrial processes.

Photocatalytic Oxidation for Maintenance of Indoor Environmental Quality

Abstract: The purpose of this paper is to provide a review of the application of photocatalytic oxidation (PCO) techniques for reduction of indoor air pollutants to assess feasibility for their application i...

Primitive environment control for preservation of pit relics in archeology museums of China.

Abstract: Immovable historical relics in some archeology museums of China suffer deterioration due to their improper preservation environment. The existing environmental control systems used in archeology museums are often designed for the amenities of visitors, and these manipulated environments are often inappropriate for the conservation of abiotic relics. This paper points out that the large open space of the existing archeology museum could be a cause of deterioration of the relics from the point of view of indoor air convective flow. The paper illustrates the need to introduce a local pit environmental control, which could reintegrate a pit primitive environment for the preservation of the historical relics by using an air curtain system, orientated to isolate the unearthed relics, semiexposed in pits to the large gallery open space of the exhibition hall.

Material Emissions and Indoor Simulation

Abstract: Building materials are important sources of volatile organic compounds (VOCs) and formaldehyde in indoor environments There is a requirement from the building designers to provide sustainable development of buildings that would encompass the consideration of health risks which could be posed by the high emissions of VOCs, formaldehyde and other organic chemicals from indoor materials and furniture, particularly during the early few years after completion of a building Buildings are now being built with much higher air-tightness requirement according to building regulations and there should be a corresponding need to further examine the emissions from building materials and to develop a system to evaluate the possible impact on indoor concentrations as a part of indoor environmental evaluation based on zero or low-carbon building scenarios This paper provides a review of the emission parameters for characterisation of material emissions, including a consideration of airflow, material loading, air exchan

Revisit of Wind Flows between Wind Tunnels and Real Canyons – The Viewpoint of Reynolds Dynamic Similarity

Abstract: Wind tunnel test and numerical simulation are two powerful methods to study air flows and pollutant dispersions around urban buildings environment. As commonly known, the development of a successful numerical model should be firstly validated by experimental results, usually by wind tunnel data [1,2], a numerical model is ultimately needed to simulate the air flows and pollutant dispersions in real street canyons [3]. It is obvious that wind tunnel models and real canyons are of different scales. The scaling effects for wind tunnel tests have already been investigated on some simple models, such as single building and normal street canyon with the aspect ratio near 1.0 (AR, denoted by building height, H, over road width, W) [4,5]. But the scaling effects on the flows around complex buildings or in real street canyons still need to be examined. In wind tunnel test, air is often used as the experimental fluid. The air velocities in the wind tunnels are several metres per second, rarely more than 20m s 1 [5,6], which are similar to the velocities in the real canyon environment. But wood blocks with height of several centimetres, subject to the experimental conditions, are adopted for the street canyon models, following that the dimensions of wood blocks are about two orders of magnitudes smaller than the real buildings. Thus, the wind tunnel experiments only satisfy the geometric similarity, but miss the Reynolds dynamic similarity in nature. On the other hand, the numerical simulations of turbulent flows with high Reynolds numbers often demand large computing resources, so that the downscaling model is always used to simulate the air flows and pollutant dispersions in urban street canyons. In such cases, building models are set in several centimetres and incoming wind velocities are given similar to the real background wind velocities; this treatment is the same as the wind tunnel test [7,8]. This means that the downscaling simulations would just satisfy the geometric similarity, but miss the Reynolds dynamic similarity. The downscaling modelling was based on the Townsend’s ‘‘Reynolds number similarity’’ hypothesis [9] and determined by the critical Reynolds numbers [1,10]. The Townsend’s hypothesis is that, in the absence of thermal and Coriolis effects and for a specified flow system whose boundary conditions are expressed non-dimensionally in terms of a characteristic length, L, and velocity, UR, the flow structure is similar with all sufficiently high Reynolds numbers. Based on the ‘‘Reynolds number similarity’’ hypothesis, the critical Reynolds numbers are only determined by the representation of minor changes in flow structures or wind profiles, in which actually the wind

Holistic Health Considerations to Prevent Sick Buildings for a Sustainable Caring Society

Abstract: Welcome to this Special Issue of Indoor and Built Environment. This Special Issue of journal papers is based on the advanced research studies that had been carried out by the Center for Sustainable Healthy Buildings (CSHeB) in Korea. The 30 papers in this Special Issue of Indoor and Built Environment were selected from presentations given in two Sustainable Healthy Buildings (SHB) Symposia held on 27 February 2012 (6th SHB) and 18 May 2012 (7th SHB) in Seoul, South Korea. These papers were further developed by the authors and peer reviewed by international experts. The International Society of the Built Environment (ISBE) is proud to be associated with this Special Issue and recommend you to study the papers presented. ISBE shares the same missions and beliefs with the CSHeB of Korea. We hope by our disseminations, we may contribute to the further advancement of innovative technologies for sustainable built environments; better designs that will improve health and wellbeing for everyone and an influence on policies and planning for sustainable development of Healthy Buildings for all cultures and nationalities. CSHeB has become one of the leading research organisations in all the subjects concerning the built environment, emphasising the need for interdisciplinary research into architectural, medical, psychological, physiological, social and environmental aspects of healthy buildings. Progress has been made in understanding the need for social integration, design, construction, maintenance and occupants’ requirements for development of sustainable and healthy buildings. A number of reports and studies have been published providing the latest ‘‘state-of-the-art’’ dissemination of research relating to lighting, ventilation, architectural engineering, social environment, SMART Homes, indoor air quality, acoustics, thermal comfort, moisture and structure for the built environment. The theme for these two SHB Symposia was: Holistic Health Considerations to Prevent Sick Buildings in a Sustainable and Caring Society. The main focus of this special issue of papers was on prevention of sick buildings due to indoor air pollution in low carbon buildings and holistic considerations for development of inclusive communities towards caring SMART design of housing and community to accommodate not just the young and able professionals but also the aged and infirmed. As the society is increasingly growing ‘‘old’’ with a higher proportion of ageing population, there is a corresponding need to assess what is required in the design of new SMART housings and communities that would accommodate the aged and infirmed people. For a caring and sustainable society, there is a need also to consider those who are ‘‘lonely’’ (low income singleton people, living alone) to introduce technologies that would enable these people to feel secure, while conserving energy consumption and to maintaining a sustainable habitat. Sustainable development and sustainable buildings are important part of architecture and governments’ guidelines and building regulations in many countries of the

Remanufacture and Reuse of Building Products for Modern Construction

Abstract: The growth in the housing market in the UK has increased the demand for sustainable wood products for building of homes and a greater use of modern methods of construction (MMC) [1–3]. There is a need to consider the feasibility of remanufacture and reuse of treated timber construction wastes and other building products recovered at the ‘‘end-of-life’’ of a house. The reuse of recovered materials should reduce the demand of timber from nonrenewable sources. The MMC method of construction of housing has rerationalized the way houses are built; with a radical change of design and careful planning, this could also be a way that would enable easy deconstruction and disassembly of structures instead of demolishing at the ‘‘end-oflife’’ of housing. The treated building units can be remanufactured and reused for new housing development; for refurbishment or for building of temporary shelters for displaced families during disaster or emergency situations. The feasibility study should include an economic (cost benefit analysis) and commercial analysis of the reuse of recovered building products such as a roof structure and trusses, windows and doors, walls including studs frames and panels, floors structures and assemblies for building and other purposes. The assessment should include a consideration of social and environmental benefits and risks; as well as technical issues concerning the design and fitting of MMC housing. The key issues for the feasibility study would be the acceptability of treated timber and other construction wastes for reuse; design and planning of MMC housing, durability and performance of the building products to be remanufactured and reused in new housing development or in emergency housing. There are extensive database records from survey of conditions of timber frames and trusses in UK homes [4,5]. These surveys have shown that the majority of timber frames and trusses of existing houses are in good condition, indicating that the majority of the timber building elements can be remanufactured and reused for new applications in the future at the ‘‘end-of-life’’ of housing. Some new wood treatment products for timber have low emission rates and low impact on building environments and health of occupants [6]. The efficacy of these treated timber products would allow their future reuse either recovered from construction wastes or after the ‘‘end-of-life’’ of housings. In order to encourage the growth in the use of recovered materials and building components, there is a need to determine the economic demand, the end-of-life value of each building components and to decide which remanufactured products suit various markets (e.g. emergency housing and self-build market) [7,8], and to assess the commercial, social and environmental benefits to effect a marketing strategy for the reclaimed and remanufactured products. There is also a need to have a radical reassessment of design and fitting of MMC housing that would enable easy deconstruction, disassembly, remanufacture and reuse of building units at end-of-life of housings. There is also a need to develop a registry of materials for building as a part of a planning permission of housing and therefore treated materials can be identified. The outcome of the feasibility study should help construction industry to lessen impacts on the

A Progress Update and History of IBE; Plus Papers of the Year, 2012

Abstract: I begin this editorial by introducing to you a talented young lady whom I met when I was attending the ‘‘Healthy Buildings 2012’’ conference held on July 8–12, 2012, in Brisbane, Australia. I was impressed by her quiet confidence and her intellectual assertiveness. She speaks good Cantonese and has a good command of English language. I attended her presentation of her paper on ‘‘Simulation based validation of two CO2-based demand controlled ventilation control logic for multiple-zone VAV system’’ and was impressed by her knowledge and command of her subject. The reason I am introducing her to you in this editorial is that she has been appointed as the Deputy Editor to assist me with the editing of papers for journal publication. Her name is Dr Josephine Lau. She is an Assistant Professor at the Charles W Durham School of Architectural Engineering and Construction, University of Nebraska-Lincoln of the USA. She, like me, was originally from Hong Kong. She was a first class honours graduate and a Master (with distinction) of Building Services Engineering from the Hong Kong Polytechnic University before she went to the USA where she obtained a further Master degree in Mechanical Engineering from Purdue University and a Doctorate degree in Architectural Engineering from Pennsylvania State University where she was also a graduate teaching assistant. She had won many awards for her thesis dissertations in America and for being an outstanding student when she was in Hong Kong. At a relatively young age, she has already established herself internationally. She is a technical committee member of the Environmental Health Committee of ASHRAE and she is an Associate Editor of the Journal of Architectural Engineering. She has published widely and internationally on a wide variety of subjects on Ultraviolet Germicidal Irradiation (UVGI) air cleaners, ventilation, floor supply displacement ventilation, HVAC systems, CFD simulation of temperature and airflow in multi-zones environments, energy efficiency and indoor air quality, in various journals and conference proceedings. I believe her expertise covers about 75% of the subject areas of our journal which has made her an ideal candidate to be the deputy editor. About 90% of papers submitted to our journal are within the subject areas of her interest, knowledge and expertise. I would also like to introduce to you Dr Zhishi Guo. He is from the US EPA Office of Research and Development, National Risk Management Laboratory, Air Pollution Prevention and Control Division (APPCD), Indoor Environment Management Branch (IEMB). He is retiring this year and he has agreed to join the editorial team of the journal as one of the deputy editors to help me with editing of papers. Zhishi does not really need introduction to many of you who know him as one of the leading experts in indoor source characterization of particulate matters, VOCs and SVOCs, modelling of VOC emissions in built environments and indoor air quality simulation. He was responsible for the US EPA simulation tool kit for indoor