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Shiming Deng - One of the best experts on this subject based on the ideXlab platform.
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a study on the thermal Comfort in sleeping environments in the subtropics measuring the total insulation values for the bedding systems commonly used in the subtropics
Building and Environment, 2008Co-Authors: Zhongping Lin, Shiming DengAbstract:Abstract The total thermal insulation value of a bedding system significantly affects the thermal neutral temperature for sleeping environments and is therefore an important variable in the Comfort Equation developed for sleeping environments reported in a related paper. This paper reports on the measurement of the total insulation values for a wide range of bedding systems (through different combinations of bed, bedding and its percentage coverage over a human body, and sleepwear) commonly used in the subtropical regions using a thermal manikin. The total insulation values of the measured bedding systems varied greatly from 0.90 to 4.89 clo, depending upon bedding, bed and mattress, the type of sleepwear, and percentage coverage of body surface area by bedding and bed. The use of a Chinese traditional style bed—Zongbang bed can provide less insulation than the use of the conventional mattress commonly used in Hong Kong. The use of so-called air conditioning quilt (summer quilt) cannot help lower the total insulation significantly. On the other hand, some factors such as people sweating and moisture permeability of the quilts, etc., were not considered in the current study but may be further studied in future work.
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a study on the thermal Comfort in sleeping environments in the subtropics developing a thermal Comfort model for sleeping environments
Building and Environment, 2008Co-Authors: Shiming DengAbstract:In the subtropics, air conditioning serves to maintain an appropriate indoor thermal environment not only in workplaces during daytime, but also at night for sleeping in bedrooms in residences or guestrooms in hotels. However, current practices in air conditioning, as well as the thermal Comfort theories on which these practices are based, are primarily concerned with situations in which people are awake in workplaces at daytime. Therefore, these may not be directly applicable to air conditioning for sleeping environments. This paper, reports on a theoretical study on a thermal Comfort model in sleeping environments. A Comfort Equation applicable to sleeping thermal environments was derived by introducing appropriate modifications to Fanger's Comfort model. Comfort charts which were established by solving the Comfort Equation, and can be used for determining thermally neutral environmental conditions under a given bedding system have been developed. A related paper reports on an experimental study on measuring the total thermal insulation values of a wide range of bedding systems commonly used in the subtropics, which are an essential input to the Comfort Equation developed and reported in this paper.
Tetsu Kubota - One of the best experts on this subject based on the ideXlab platform.
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comparative assessment of vernacular passive cooling techniques for improving indoor thermal Comfort of modern terraced houses in hot humid climate of malaysia
Solar Energy, 2015Co-Authors: Tetsu KubotaAbstract:Abstract The main objectives of this study were to investigate vernacular passive cooling techniques and their potential application for improving indoor thermal Comfort of naturally ventilated, modern brick terraced houses in Malaysia. Field measurement was conducted in two traditional timber Malay houses and two traditional masonry Chinese shophouses to examine their indoor thermal environments. The results of the former showed that the indoor air temperatures were higher than the outdoor air temperatures by 1 °C during daytime under open window conditions and 2 °C at night under closed window conditions on average. The emphasis was on reducing the temperature of the outdoor air before entering the lightweight house for bodily cooling by cross ventilation. The outdoor air temperature at the Malay house sites was lower than that of the terraced house site by 1.7 °C on average. The results of the latter revealed that indoor air temperatures in rooms that were adjacent to small internal courtyards were lower than the immediate outdoors by about 5 °C on average at the peak period. At night, the indoor air temperatures maintained values that were similar to the outdoors. The small courtyards were effective to cool the high thermal mass structures through nocturnal ventilative and radiative cooling. When assessed using an adaptive thermal Comfort Equation for hot–humid climates, the periods of indoor operative temperatures exceeding the 80% Comfortable upper limit in the Malay houses, Chinese shophouses, daytime ventilated and night ventilated terraced houses were 47%, 7–8%, 91% and 42%, respectively, on fair weather days. Potential passive cooling techniques for the existing terraced houses including night ventilation, roof or ceiling insulation, window and wall shading, small courtyard concept, and microclimate modification and/or urban heat island mitigation were discussed.
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development of an adaptive thermal Comfort Equation for naturally ventilated buildings in hot humid climates using ashrae rp 884 database
Collection of Frontiers of Architectural Research, 2013Co-Authors: Tetsu KubotaAbstract:Abstract The objective of this study was to develop an adaptive thermal Comfort Equation for naturally ventilated buildings in hot–humid climates. The study employed statistical meta-analysis of the American Society of Heating, Refrigerating and Air-Conditioning Engineers (ASHRAE) RP-884 database, which covered several climatic zones. The data were carefully sorted into three climate groups including hot–humid, hot–dry, and moderate and were analyzed separately. The results revealed that the adaptive Equations for hot-humid and hot-dry climates were analogous with approximate regression coefficients of 0.6, which were nearly twice those of ASHRAE and European standards 55 and EN15251, respectively. The Equation using the daily mean outdoor air temperature had the highest coefficient of determination for hot–humid climate, compared with other mean temperatures that considered acclimatization of previous days. Acceptable Comfort ranges showed asymmetry and leaned toward operative temperatures below thermal neutrality for all climates. In the hot–humid climate, a lower Comfort limit was not observed for naturally ventilated buildings, and the adaptive Equation was influenced by indoor air speed rather than indoor relative humidity. The new Equation developed in this study can be applied to tropical climates and hot–humid summer seasons of temperate climates.
Fitri Yakub - One of the best experts on this subject based on the ideXlab platform.
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Effectiveness of free running passive cooling strategies for indoor thermal environments: Example from a two-storey corner terrace house in Malaysia
Building and Environment, 2019Co-Authors: Ng Wai Tuck, Ahmad Zaki, Aya Hagishima, Hom Bahadur Rijal, Mohd Azuan Zakaria, Fitri YakubAbstract:Abstract The widespread use of air-conditioning to achieve indoor cooling of residential buildings has caused increased electricity consumption. Effective passive cooling strategies, such as natural ventilation, are important for reducing energy consumption. Field measurements of thermal performance for a corner terrace house in Kuala Lumpur were conducted to clarify the effectiveness of free running (FR) ventilation as a passive cooling strategy with configurations: without ventilation, full ventilation, day ventilation, and night ventilation. Measurements were conducted for all bedrooms and a family area on the first floor. For comparison, a mixed mode (MM) consisting of FR, ventilation with a ceiling fan, and cooling with an air-conditioner, which represents the actual conditions of this house, was measured in the living and dining area on the ground floor. Operative temperature was compared with the predicted temperature using an adaptive thermal Comfort Equation (ACE) under relevant international standards. The mean indoor temperature under FR was approximately 27~37 °C, and 27~33 °C in MM. Full ventilation and day ventilation recorded better correlation between outdoor and indoor temperature compared with no ventilation and night ventilation. Furthermore, compared with the ACE for a hot-humid climate, MM ventilation resulted in an operative temperature 58% less than the acceptable Comfort temperature; thus, it performed better and was closer to international standards than was FR ventilation, which resulted in an operative temperature of 27% less than the acceptable Comfort temperature. FR was not adequate to provide Comfortable conditions without assistance from MM.
Ng Wai Tuck - One of the best experts on this subject based on the ideXlab platform.
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Effectiveness of free running passive cooling strategies for indoor thermal environments: Example from a two-storey corner terrace house in Malaysia
Building and Environment, 2019Co-Authors: Ng Wai Tuck, Ahmad Zaki, Aya Hagishima, Hom Bahadur Rijal, Mohd Azuan Zakaria, Fitri YakubAbstract:Abstract The widespread use of air-conditioning to achieve indoor cooling of residential buildings has caused increased electricity consumption. Effective passive cooling strategies, such as natural ventilation, are important for reducing energy consumption. Field measurements of thermal performance for a corner terrace house in Kuala Lumpur were conducted to clarify the effectiveness of free running (FR) ventilation as a passive cooling strategy with configurations: without ventilation, full ventilation, day ventilation, and night ventilation. Measurements were conducted for all bedrooms and a family area on the first floor. For comparison, a mixed mode (MM) consisting of FR, ventilation with a ceiling fan, and cooling with an air-conditioner, which represents the actual conditions of this house, was measured in the living and dining area on the ground floor. Operative temperature was compared with the predicted temperature using an adaptive thermal Comfort Equation (ACE) under relevant international standards. The mean indoor temperature under FR was approximately 27~37 °C, and 27~33 °C in MM. Full ventilation and day ventilation recorded better correlation between outdoor and indoor temperature compared with no ventilation and night ventilation. Furthermore, compared with the ACE for a hot-humid climate, MM ventilation resulted in an operative temperature 58% less than the acceptable Comfort temperature; thus, it performed better and was closer to international standards than was FR ventilation, which resulted in an operative temperature of 27% less than the acceptable Comfort temperature. FR was not adequate to provide Comfortable conditions without assistance from MM.
A F Emery - One of the best experts on this subject based on the ideXlab platform.
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sensitivity of the human Comfort Equation and of free convection in a vertical enclosure as examples of the use of global sensitivity to evaluate parameter interactions
Journal of Heat Transfer-transactions of The Asme, 2010Co-Authors: A F Emery, Ann M MescherAbstract:Many models of engineering and scientific systems involve interactions between and among the parameters, stimuli, and physical properties. The determination of the adequacy of models for predictions and for designing experiments generally involves sensitivity studies. Good designs mandate that the experiments be sensitive to the parameters sought with little interaction between them because such interaction generally confuses the estimation and reduces the precision of the estimates. For design purposes, analysts frequently want to evaluate the sensitivities of the predicted responses to specific variables, but if the variables interact it is often difficult to separate the effects. Global sensitivity is a technique by which one can evaluate the magnitude of the interactions between multiple variables. In this paper, the global sensitivity approach is applied to the human Comfort Equation and to free convection in a rectangular enclosure. It is found that when occupants are unComfortable, there is little interaction and that one can predict the effects of changing several environmental conditions at once by adding the separate effects. But when occupants are Comfortable, there is a large interaction and the effects cannot be treated separately. Free convective heat transfer in an enclosure is a function of the Rayleigh number Ra and the aspect ratio H/W, and the flow field changes from unicellular to multicellular as Ra increases. There is a strong interaction for H/W≤ 2 but little for H/W≥2.
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sensitivity of the human Comfort Equation an example of the use of global sensitivity to evaluate sensitivity interactions
ASME JSME 2007 Thermal Engineering Heat Transfer Summer Conference collocated with the ASME 2007 InterPACK Conference, 2007Co-Authors: A F EmeryAbstract:Many models of engineering and scientific systems involve interactions between and among the parameters, stimuli, and physical properties. The determination of the adequacy of models for predictions and for designing experiments generally involves sensitivity studies. This is particularly true for experiments by which properties are to be estimated. Good designs mandate that the experiments be sensitive to the parameters sought with little interaction between them because such interaction generally confuse the estimation and reduce the precision of the estimates. For design purposes, analysts frequently want to evaluate the sensitivities of the predicted responses to specific variables but it the variables interact it is often difficult to separate the effects. Global sensitivity is a technique by which one can evaluate the magnitude of the interactions between multiple variables. In this paper the global sensitivity approach is applied to the human Comfort Equation. The aim is twofold: 1) to demonstrate the usefulness of the global sensitivity approach, 2) to increase our understanding of how human Comfort is affected by activity, clothing, and environmental conditions. It is found that when occupants are unComfortable there is little interaction and that one can predict the effects of changing several environmental conditions at once by adding the separate effects. But when occupants are Comfortable there is a large interaction and the effects cannot be treated separately.Copyright © 2007 by ASME