A PERFORMANCE-DRIVEN DESIGN MODEL OF TERRITORIAL ADAPTIVE BUILDING SKIN (TABS) FOR DAYLIGHTING PERFORMANCE OPTIMISATION IN OFFICE BUILDINGS IN EGYPT

Abstract

Building skins have become an expression of the unique forces that are defining their context, either tangible such as weather conditions or intangible, such as social and cultural heritage. Egypt is currently experiencing excessive importation of Western technology and design concepts in architecture due to the desire of rapid development accompanied by social and political changes, threatening its culture and causing an identity crisis. Nowadays, office building design in Egypt adopts the design principles of fully glazed western buildings that were built for different environmental conditions and cultures. The negligence towards local climates and heritage, especially in a country with a hot desert climate and a rich culture like Egypt, resulted in unsatisfactory building performance. The satisfaction of occupants with their work environment is important, both regarding well-being and productivity. Therefore, ensuring acceptable environmental conditions must be achieved along with the need to include sustainability–performance related features within any design. For office buildings, two of the primary energy demands are associated with artificial lighting and thermal comfort. Therefore, any approach that attempts to reduce excessive solar gains while enhancing daylight availability can be considered as a sustainable design strategy. Building skin is the key moderator between the internal and external environments. Historically, the environmental control through facade was static. However, recent technological advances enabled building skins to dynamically react to the external environment with the aim of enhancing internal conditions. Territorial adaptive building skin (TABS) is one example of this new types of building skins. The methodology proposed in this research employed a parametric modelling, building performance simulation and Genetic Algorithm tools for optimising the performance of TABS for a south facing office space in Cairo, Egypt, based on predefined criteria, at twelve different times during the year. The TABS integrated two subsystems: (1) Shading: a dynamic geometric pattern inspired by the Egyptian solar screen ‘Mashrabia’; (2) Daylight redirecting: active horizontal louver system, to harness the advantages of both strategies. The results showed that TABS achieved the required performance at all the twelve examined times using it's predefined capabilities regarding six performance indicators (task points illuminance levels, illuminance contrast ratio, daylight distribution, daylight penetration depth, solar gain and glare). Moreover, the TABS performance surpassed the performance of the fully glazed base case and two other optimised traditional facade solutions at all examined times. Furthermore, in this study, each physical appearance of the optimised TABS solutions was an authentic representation of the Mashrabiya form, which continually achieved to represent the Egyptian cultural identity. An empirical validation process was conducted using 3D printed physical models of optimised TABS in an artificial sky facility. Acceptable agreement between the validation and simulation models regarding illuminance values was achieved. Finally, the findings proved that TABS could be a complex geometry that satisfies the ornamental desires of the contemporary architecture and address the concerns over building performance and user comfort.