Courtyards as passive design solution for school buildings in hot areas: UAE as a case study
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Date
2018-06
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The British University in Dubai (BUiD)
Abstract
The global concentration on green efficient schools is growing as schools represent a considerable sector in the built environment, which consumes a lot of energy to provide a standard level of thermal comfort for students. In the UAE, both private and public-school buildings are assumed to be a high energy consumption sector, in addition to universities, banks and shopping malls. Moreover, the energy consumption in schools seems to be encouraged rather than controlled, thus there is the potential for reducing the sector’s energy consumption. Traditional architecture adopted the courtyard design as a distinct form to create the core of houses and moderate the thermal conditions for the surrounding spaces, especially in hot climates. In most of the previous studies on the subject, courtyards were found to be related to houses or buildings in general, rather than educational institutions specifically, such as schools. This research aims to investigate the integration of a well-designed courtyard as a passive design strategy in buildings in the UAE to reduce the energy consumption required for cooling. In addition, the improvements in the thermal comfort conditions within the courtyards should translate to a more comfortable outdoor space for the students.
This research adopted a qualitative approach based on case studies and computer simulations. The case studies were five present public schools’ buildings with different plan templates and different courtyard configurations; the schools are models 586, 596, KAT, UPA1 and finally UPA-fin. The computer analysis in this research was based on two software programs: ENVI-met software to evaluate changes in the schools’ microclimates due to the presence of courtyards and IESve software to calculate the energy consumption of the school buildings due to the changes of the microclimates affected by the courtyards. The thermal effect of the courtyards on the school buildings was investigated through two stages. The first stage discussed the orientation of the courtyard. The second stage investigated a range of courtyard configurations and designs through five phases, each focused on one of five relevant parameters which are: courtyard’s shape factor ratio (W/L ratio), courtyard’s area to built-up area (CA/BA ratio), courtyard’s outline shape, courtyard’s height (number of floors) and finally courtyard’s vegetation. There was third stage in this research that investigated the cooling loads for schools (case studies) in relation to the orientation and the design strategies. The cooling plant sensible load was investigated the beginning on specific dates and then it was investigated for the whole academic year.
The outcomes of the research investigations concluded that the design and the properties of the courtyards can affect the indoor temperature of the school building, thus the cooling load. Moreover, the results of the computer simulation revealed that the school UPA-fin was the best school case with the optimum courtyards after adopting the following strategies 1- orientation to the north , 2-CA/BA ratio 20%, 3-square outline for the courtyards, 4-additional third floor on the east mass mainly 5- integrating vegetation in the courtyards, succeeded in reducing the Tin to 1.9 ˚C on 21st of September and 1.7 ˚C on 21st of March and that managed to reduce the cooling load by 19% on 21st of September and 27% on 21st of March compared to the basic UPA-fin to the north in phase one .
The investigation of the annual cooling load after adopting only four strategies that included 1- orientation, 2-CA/BA ratio 20%, 3-square outline for the courtyards, 4-additional third floor on the east mass mainly and excluding the integration of vegetation, succeeded in reducing the cooling load by 16.5%compared to phase one UPA-fin basic to the north.
The results showed that the optimum courtyard had the best predicted mean vote (PMV) performance also, as on 21st of September the max PMV reading for the poorest case of stage two equaled 4.35, which covered 48% of the courtyard’s area, while the max PMV reading for the best case of stage two (phase five) equaled 3.15 and covered 1.5% of the courtyard’s area with a reduction of about 1.2 on the PMV scale. On the other hand, on the 21st of March the max PMV reading for the poorest case of stage two equaled 3.0 and covered 48% of the courtyard’s area; while the max PMV reading for the best case equaled 1.9 and covered 1.5% of the courtyard’s area, with a reduction of about 1.1 according to the PMV scale.
The research results revealed that the optimal design of the courtyard can reduce the temperature of the inner spaces of the school, thus it can reduce the cooling load for the school building in general. Moreover, it can improve the thermal comfort for the outdoor areas. The findings of this study will be important for architects, sustainable developers, educational developers, economic consultants and green buildings designers in UAE and in areas with similar climate to help them in designing green schools.
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Keywords
Buildings -- Environmental engineering., passive design solution, school buildings, United Arab Emirates (UAE), hot areas, built environment, thermal comfort