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Global consumption of energy is increasing over time as a result of the continuous increase in population and urbanism. This includes energy consumed in buildings in both construction and operation stages, where significant amount of energy is consumed in heating and cooling. As a matter of fact, most buildings in the Gaza Strip are constructed wit...
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Citations
... conducted a parametric three-dimensional modelling study using Computational Fluid Dynamics (CFD) to assess the impact of building grouping patterns on the outdoor wind conditions and the ventilation of the buildings. A further study by Ref. [6] indicates that most buildings in Gaza are constructed without the use of thermal insulation, which consequently increases the reliance on mechanical cooling and heating for the inhabitants' thermal comfort. The study concluded that thermal insulation in walls and roofs would lower all unnecessary heat gains and losses in a year by 17%. ...
Residential and commercial buildings consume over a third of the world's total energy. The residential sector accounts for most energy use in the Gaza Strip, necessitating the development of feasible energy-saving techniques. Herein, a simulation-based study has been prepared to examine the integration of some practical passive design strategies into a generic residence. The study aims to optimize thermal performance by minimizing the building's cooling loads. A detailed examination is conducted for the literature on similar research and passive design techniques to investigate a city's state and climate. Three passive parameters, namely, shading devices, natural ventilation, and thermal insulation, were investigated using Climate Consultant and IESve as assessment software. Accordingly, their impacts on the building's indoor temperature and cooling load were evaluated. The findings suggest that the implementation of such passive design parameters can reduce energy consumption by 9.89 kW, representing 59% of the total energy consumption of the building. Such integration in residential buildings could be significant in cities with limited natural resources and would guide architects, designers, engineers towards the potential of passive measures in building design.
... conducted a parametric three-dimensional modelling study using Computational Fluid Dynamics (CFD) to assess the impact of building grouping patterns on the outdoor wind conditions and the ventilation of the buildings. A further study by Ref. [6] indicates that most buildings in Gaza are constructed without the use of thermal insulation, which consequently increases the reliance on mechanical cooling and heating for the inhabitants' thermal comfort. The study concluded that thermal insulation in walls and roofs would lower all unnecessary heat gains and losses in a year by 17%. ...
Residential and commercial buildings consume over a third of the world’s total energy. The
residential sector accounts for most energy use in the Gaza Strip, necessitating the development of
feasible energy-saving techniques. Herein, a simulation-based study has been prepared to
examine the integration of some practical passive design strategies into a generic residence. The
study aims to optimize thermal performance by minimizing the building’s cooling loads. A
detailed examination is conducted for the literature on similar research and passive design
techniques to investigate a city’s state and climate. Three passive parameters, namely, shading
devices, natural ventilation, and thermal insulation, were investigated using Climate Consultant
and IESve as assessment software. Accordingly, their impacts on the building’s indoor temperature and cooling load were evaluated. The findings suggest that the implementation of such
passive design parameters can reduce energy consumption by 9.89 kW, representing 59% of the
total energy consumption of the building. Such integration in residential buildings could be
significant in cities with limited natural resources and would guide architects, designers, engineers towards the potential of passive measures in building design.
... Several strategies are used to provide thermal insulation for the final roofs. This includes the use of typical layered insulators such as polystyrene [7], the use of green roofs [8], the use of white painting [9], and the use of moving air cavities [10]. ...
... In winter, the roof was able to maintain a value that is 4 °C higher on average. Asfour and Kandeel [7] carried out a study of thermal performance modelling with reference to thermal insulation. The study considered multi-storey residential buildings located in hot climates as a main focus, where thermal insulation of external walls and roofs has been examined. ...
... This causes several problems such as the uncompleted facades, the unfinished exterior, and the uninsulated top roof. Taking the latter problem as a focus of this paper, the top floor in this case usually suffers from excessive heat gains in summer and excessive heat losses in winter [7]. The usual treatment is to apply thermal insulation to this roof. ...
This study focuses on the uncompleted multi-storey residential buildings located in hot
climates. This construction pattern is common in the case of incremental housing, where
additional floors are added to the building as housing needs grow. Top roofs in these
buildings are usually left without thermal insulation until the rest of upper floors are
erected. This causes higher thermal discomfort in the top flats compared to the lower
ones. Thus, the aim of this study is to investigate thermal effect of some proposed
temporary measures that are intended to protect these roofs from unwanted heat gains
until the rest of storeys are constructed. This has been carried out using thermal
modelling to find out the effect of these measures on the amount of heat transfer through
the roof in both summer and winter times. The analysis showed that it is possible to
achieve competent thermal protection of the top roof compared to the layered thermal
insulation using simple, cost-effective, and reversible measures. Among the examined
measures, covering the roof with white foldable sheets and the use of pergolas have been
found to be the most effective measures. In both cases, a reduction of 38% in conductive
heat transfer through the top roof in summer was observed compared to the unprotected
modelling case.
... Several investigations were devoted to study and develop various correlations to estimate Nusselt number, Nu, at different Prandtl number, Pr, Raleigh number, Ra L , Garshof number, Gr L and length and height of the enclosure, to investigate the natural convection heat transfer mechanism through the enclosures [3]. One wall cavity that contains stationary air, which analogues to the geometry of vertical enclosure, has been investigated to evaluate its effectiveness as thermal insulator in buildings [4,5]. Muhaisen (2015) checked various wall components designs including ones that contain air gap (i.e. one wall cavity). ...
The present work examines a system that uses two separate wall cavities filled with stationary air which can be used as a thermal insulator in buildings. Specifically, it investigates the use of two separated wall cavities that trap stationary air inside each one and placed in a building wall where the heat transfer is expected. To carry out this study, the rate of heat transfer through this wall is first calculated with the assumption of pure conduction (i.e. trapped air in the two wall cavities is assumed to be stationary). Then natural convection heat transfer rates through the two wall cavities are estimated based on the Nusselt numbers and hence the dominating heat transfer mechanism (conduction and/or convection) for each wall cavity is explored. Taking into account all the above, introducing two cavities filled with stationary air to building wall can work effectively as thermal insulator as indicated by lower Nusselt numbers and hence lower convection heat transfer rates through the two wall cavities. The advantage of using two wall cavities over one wall cavity of larger thickness is also investigated and evidenced by the higher convection heat transfer rates which are associated with one wall cavity of larger thicknesses – that's the wall with two cavities can effectively resist the heat flow than the wall with one cavity of larger thickness.
... Housing designers and planners should get involved in this regard. Furthermore, efficiency of housing design and planning is fundamental in the saving of our natural resources, as 50% of the global resources go into construction [3]. ...
Population density in the Gaza Strip rapidly increases overtime. Considering the limited area of the Gaza Strip, there is a need to rationalise consumption of the limited available housing land. In this context, there is a need for innovative solutions that help increasing housing design efficiency. This study addresses the potential of housing design flexibility as a possible solution. It examines residents’ attitude towards design flexibility as a starting point in this regard. To achieve this aim, the study carried out a field study based on a questionnaire. The quantitative analysis of the questionnaire leaded to accept the study main assumption that residents are satisfied with the idea of implementing design flexibility in residential spaces and furniture design in order to increase the efficiency of their housing units. This is true regardless several examined variables including income level. Thus, the study recommends implementing design flexibility in the housing market as a strategy that helps rationalization of resources consumption, in addition to securing adequate housing for all.
The present study investigates the use of two air cavities thermal insulator in buildings. The two air cavities insulator structure is supposed to be located within the building's wall and roof forming two separated vertical and horizontal cavity, respectively. In addition, the wall cavity height (or roof cavity length), H, was investigated at H = 2, 3, 4, 5 m to find the influence of wall cavity height (or roof cavity length) on various thermal characteristics and thus to determine the thermal optimum thickness. At each wall cavity height (and roof cavity length), cavity thickness, Lc, was varied from 0.01 m to 0.1 m forming aspect ratio, AR = H/Lc ranges of 20 to 200, 30 to 300, 40 to 400, and 50 to 500 for H = 2, 3, 4, and 5 m, respectively. The present results reveal the presence of the first and second cavities in wall and roof at various thicknesses affecting the development of wall and roof components' surface temperature. In addition, varying the wall cavity height or roof cavity length has further significant effects on the development of these surface temperatures. Moreover, it was found that increasing the wall cavity height leads to increasing the optimum wall cavity thickness, Lc = 0.024, 0.027, 0.029, and 0.031 m at cavity height, H = 2, 3, 4, and 5 m, respectively, whereas in the roof cavity case, the optimum roof cavity thickness seems to reach its asymptotic value at about 0.019 m for the roof cavity length investigated, H = 2, 3, 4, and 5 m despite the optimum wall cavity thickness that was not.
This work presents an analytical and computational study on the use of two separated air cavities, located in common walls and roofs, as an application for thermal insulation in buildings. The aspect ratios of the two cavities were varied from 10 to 100. Firstly, the thermal analysis is performed, under the assumption that air in the two cavities is motionless, to determine the influence of cavity aspect ratio. The results show that the thermal diffusivity of buildings’ wall and roof components is sensitive to the presence of first and second air cavities as well as to the variation of cavity aspect ratio. In addition, the natural convection thermal analysis across the two separated air cavities, for isothermal case, was performed to assess the influence of aspect ratio on various natural convection parameters. The results show that the Rayleigh number decreases with small range of aspect ratio, but remain nearly constant in high range of aspect ratio. The optimum aspect ratio of the two separated air cavities (i.e., optimum cavities thicknesses) is determined. At each air cavity, the optimum cavity aspect ratio will be at a location where Nusselt number \(Nu = 1\). At this location, the natural convection heat transfer rate approximates pure conduction heat transfer rate, and thus, the cavities can work optimally as thermal insulators. The results revealed that the optimum aspect ratios for the two wall and two roof air cavities are 50 and 52.6 corresponding to optimum thicknesses of 0.02 and 0.019 m, respectively.
