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Development of an adaptive thermal comfort equation for naturally ventilated buildings in hot-humid climates using ASHRAE RP-884 database
Doris Hooi Chyee Toe, Tetsu Kubota
Front. Archit. Res.. 2013, 2 (3): 278-291.
https://doi.org/10.1016/j.foar.2013.06.003
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.
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Choosing heat sinks for cooling in tropical climates
Marcel Bruelisauer, Forrest Meggers, Hansjürg Leibundgut
Front. Archit. Res.. 2013, 2 (3): 292-300.
https://doi.org/10.1016/j.foar.2013.05.004
Efforts to limit CO2emissions from buildings in the tropics either focus on reducing energy demand, i.e., air-conditioning, or on replacing fossil with renewable sources. The link between energy demand and supply is often overlooked, especially the effect of the temperature lift of air-conditioning systems on energy consumption. But while heat and humidity gains define energy demand, operating temperatures of the system define the necessary energy input. We aim to transfer our experience of using the LowEx paradigm for heat pump systems in moderate climates to the tropical climate of Singapore. In this paper, we took a systematic overview of a range of heat sinks, to which we refer to as anergy sinks. We analysed their thermal properties and their effect on the performance of air-conditioning systems, expressed as COP. The predominantly used dry air-cooled condenser units performed worst, especially when subject to a stack effect in (semi-)confined spaces. The performance is highest for cooling towers using the wet bulb temperature followed by water body based anergy sinks and the soil. The wide spread of results confirms that the heat rejection temperature is a decisive factor for the performance of the overall cooling system and the input of primary energy.
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Relationship between tile exfoliation and moisture content
Sadayuki Onmura, Shuichi Hokoi, Daisuke Ogura
Front. Archit. Res.. 2013, 2 (3): 301-309.
https://doi.org/10.1016/j.foar.2013.07.001
In Japan, tile exfoliation from external walls is a serious problem that must be prevented. In our previous study, a tiled concrete sample was dried at a temperature of 105 °C for preconditioning. Then, tile exfoliation occurred. Since this seemed to indicate a relationship between tile exfoliation and moisture content, it was further pursued in this study. First, drying experiments on concrete samples just after tiling were carried out under different ambient air temperatures. The following results were obtained. ●Tile exfoliation occurs even at the lower drying temperatures. ●Tile exfoliation starts at corner tiles (seen in all experiments). ●When the average moisture content of the tiled concrete sample becomes lower than a certain value, tile exfoliation occurs. Next, the experiments were analyzed using a three-dimensional model of simultaneous heat and moisture transport. The calculated moisture content agreed well with the measured results. By comparing the measurement and simulation results, it is considered that the tiles are exfoliated when the moisture content of the mortar on the back side of the tile becomes lower than a certain value. Therefore, the moisture content can serve as an index for evaluating the occurrence of the tile exfoliation.
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Uncomfortable prototypes: Rethinking socio-cultural factors for the design of public housing in Billiri, north east Nigeria
Joy Joshua Maina
Front. Archit. Res.. 2013, 2 (3): 310-321.
https://doi.org/10.1016/j.foar.2013.04.004
Public housing delivery in developing countries often involves the provision of governmentfunded housing units. Over time, occupants transform such units to suit their changing needs or to increase and improve housing stock—a practice that has been the focus of several documented studies intended to inform policy makers about changing housing trends. Abandoned units have, however, received comparatively less attention. The present paper reports findings from the documentation and analyses of abandoned and modified prototype units in Billiri, the main town occupied by the Tangale community in north east Nigeria. The methodology involves space syntax methods, as well as the analyses of space use patterns in 45 randomly selected compounds built by the community and in two sets of prototype housing units in the study area. Results suggest that socio-cultural factors related to kinship, security, and basic needs, which form part of the community heritage, are inadequately reflected in the location and design of the units, accounting for their abandonment and modification. These findings have implications for future housing policies in the area.
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Visual language in Mamluk architecture: A semiotic analysis of the Funerary Complex of Sultan Qaitbay in Cairo
Nelly Shafik Ramzy
Front. Archit. Res.. 2013, 2 (3): 338-353.
https://doi.org/10.1016/j.foar.2013.05.003
Cultural background plays a significant role in the sphere of visual art. Semiotics as a discipline is recognized as a useful tool in gauging cultural background and identifying signs that might represent the message of a certain work. Given the rich cultural context of Mamluk architecture, this form of art can be used in studying semiotics. Semiotic tools were employed to interpret the expression of architectural forms and to formulate a subsequent understanding of these architectural forms by turning each element into a communication tool that elucidates meaning. The Sufie tradition was the dominant Islamic practice during the Mamluk period, during which metaphysics, numbers, and geometry were regarded as indispensable tools in manifesting the nature of divinity and the order of being. A semiotic reading of the Funerary Complex of Sultan Qaitbay in Cairo, regarded as one of the perfect works of this era, was proposed to study the reflections of these notions on architectural works. Several messages were embodied in the building, such as functional or technical messages. The semiotic reading in this study is solely concerned with the spiritual message of the building.
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