Multi-objective optimisation of urban courtyard blocks in hot arid zones.

• Residential Solar Blocks are reconceptualised in a hot-arid climate. • GAs are used for MOO of microclimatic and energy performance of the blocks. • Pareto optimal solutions had 12 m interspaces and orientated NE-SW and NW-SE. • Optimal solutions could reduce cooling loads by 31.7% and reduce UTCI by 1.6 °C. • Optimal solutions could increase the percentage of exposed surfaces in winter by 4%. Courtyard blocks are well known for their tempering potential of the thermal conditions in various climates. In this paper, the building heights, orientation and interspaces of courtyard blocks are optimised for the hot-arid climate of Cairo, Egypt. Simulations are conducted using an evolutionary search algorithm within the Grasshopper parametric design environment for Rhino 3D. The Ladybug-tools, plugins of Grasshopper were used to calculate the objective functions, the summer weekly cooling loads and the weekly average Universal Thermal Climate Index (UTCI). For three courtyard block types elongated 1, 2 and 3-fold the width of the inner court, the Pareto optimal sets of the three types all comprised solutions with the minimum interspaces. Orientation 45° was predominant in the square type, whilst orientation 135° was predominant in the elongated types (W/L = 2, 3). Using the weighted sum ranking, with the exception that orientation 45° was preferred in the most elongated type, the optimal solutions reduced cooling loads by up to 31.7% and reduced UTCI by up to 1.6 °C, compared to a reference case. Solar radiation analysis showed that the optimised cases have great potential to increase the percentage of exposed surfaces by 4% to reduce the heating loads in winter. [ABSTRACT FROM AUTHOR]