Solar Energy

Volume 170, August 2018, Pages 358-368

Assessment of skylight design configurations on daylighting performance in shopping malls: A case study rights and content


In Egypt and the Middle East, there is an obvious tendency of establishing new shopping malls and indoor commercial centers that provide collective facilities. However, they are accompanied by multiple design challenges including the provision of natural lighting for the interior spaces, which requires a careful consideration for the environmental design aspects. This research aims to provide a methodology to assess and optimize skylight designs to achieve better daylighting performance. A case study for a shopping mall in Cairo is selected where different skylight design configurations are examined. Skylight parametric variations include different opening ratios and visual transmittance values. Daylighting performance is tested in regards with daylit area coverage, potential for glare and accompanied energy consumption used for artificial lighting. A parametric simulation for 50 different cases are conducted and a multiple-criteria optimization is carried out to optimize material and ratio of size. Other parameters could be investigated in further researches. The optimum solution is further extracted and compared to the current base case. These results shows that early considerations in skylight and interior design could achieve more than 50% reduction in the overlit area, while achieving minor improvements in the daylit area. Yet, retrofitting measures are applicable for post construction and occupation periods.


Nowadays in the Middle East and Egypt, shopping and commercial malls are increasingly built in the cities and outskirts. The reason behind this increasing number is due to the facilities that those commercial centers provide, such as multiple services in one place, easy parking, security, and air conditioned area especially in hot arid climates (Keng et al., 2007). Thus, huge investments are directed towards building more commercial malls in these countries, which creates a competitive environment between investors and architects. Even though huge shopping mall requires a huge amount of energy, in terms of embodied and operational energy needed to operate specifically mechanical systems and artificial lighting, contemporary designs usually neglects the environmental aspects of the design, which consequently leads to- increasing energy consumption. Given that building sector consumes around (46.2%) of the overall energy (HBRC, 2009). Egypt has faced several blackouts due to an extreme shortage in generating electricity in the last few years, which rises the alarm of the importance to consider our energy consumption rates and design practices. Even though Egypt is gifted by clear sky most of the year, those buildings are poorly designed to achieve a maximum benefit from the natural light. One of the main problem of those shopping malls is due to the arrogance tendency of the designers and architects to only consider the luxurious aesthetic aspects that satisfies the needs of the investors and public rather than integrating the environmental aspects and creating some tradeoffs during the design process.

Given the skylight as one of the most common elements used when designing indoor shopping malls, its main aim is to provide natural lighting for the closed indoor spaces of the court yards and corridors. Daylighting is effective in building design affecting efficiency of spaces. When daylight is taken into consideration, more comfort could be achieved and energy consumption could be reduced. Daylight is considered as the best source of light as it strongly reaches human visual reaction. It gives a sense of brightness that can have a great influence on the people (Li et al., 2006). This research aims to address the design parameters of skylights in the indoor shopping malls, in terms of opening ratio and material that provides an optimum daylighting. The objective of this research is to assess daylighting performance of the skylight of an existing shopping mall in Cairo as a case study, and to investigate an optimized skylight design parameters that enhances the daylighting performance for the indoor spaces, in addition to investigating the equivalent reduction in the energy consumption used for artificial lighting. Followed by a literature review on daylighting and its measuring methods, a case study is selected for the investigation and analysis. The case study is modeled using Rhinoceros 3D software and DIVA for Rhino in Grasshopper for parametric simulation and optimization. The results are further post processed to generate visual graphics and select optimum skylight parameters. This study addresses architects and investors who are in charge of building shopping malls in the Middle East and Egypt specifically. It provides a guidance and a methodology to assess and optimize skylight designs in shopping malls to reduce energy consumption used for artificial lighting while providing visual comfort.

In the first section of this article, an introduction is provided for this research, followed by the second section that presents a review on the previous literature on the same topic. The third section states the methodology used to analyze, assess and optimize the skylight of the selected case study. The fourth section presents and analyzes the selected case study while stating the boundary conditions of the simulation and optimization. In the fifth section, the results are presented and a correlation between skylight ratio, material and daylighting performance are illustrated. The sixth and last section raises the argument on skylight design in hot climates and the means and opportunities of applying optimized and retrofitting measures on the existing indoor shopping malls in the country and the region.

Section snippets

Daylighting in hot climates

Daylighting is an essential component in the holistic environmental design of buildings. When skillfully introduced, daylight creates an ambience of quiet contemplation and visual comfort, in addition to the tendency of minimizing the usage of artificial lighting and environmental adapting devices (American Architectural Manufacturers Association (AAMA), 1987). Thus, the architectural design is the main factor that defines the quality of indoor daylighting availability. Daylight availability


Multiple studies of skylights from different locations were reviewed in this research in order to extract the followed methodologies and results used in previous researches. The review included skylights in different shapes and design configurations as well. Afterwards, a case study was selected for examination and analysis. A shopping mall located in Cairo, Egypt, was selected as a case study representing a commercial building in a hot climate area.

The adopted methodology and tools in this

Building configuration

The case study is located in El-Maadi district in southern Cairo, Egypt. The case study represents an indoor shopping mall called “The Grand Mall”, a commercial center consists of six floors including the basement. Fig. 1 gives an overview for the interior spaces of the shopping mall.

There are three main reasons for choosing this building. First, it is located in Cairo, which represents the city with the largest number of existing and under construction shopping malls in Egypt. Second, the

Base case

In Table 4, the results of each of the six floors are presented. Three main values are given for each floor; Daylit area, Potential for Glare and energy consumed by artificial lighting. Daylighting results are presented throughout a colored legend, by which the violet color is added to present the area with the potential for Glare. The results shows that the ratios of the Daylit Area (DA100 Lux 50%) for the whole six floors ranges between 2% and 14% with an average Daylit area of 8.2%. The


In this article, a methodology for a multi-criteria optimization for skylight design configurations is represented. A case study from Cairo, Egypt is selected as a represenative for shopping malls in the region, where daylighting, potential for glare and energy consumption were assessed. 50 different skylight designs were parametrically examined aiming to find an optimum configurations for opening ratio and visual transmittance value for the existing skylighting. This research proves that huge

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