Impact of commercial land mixture on energy and environmental performance of mixed use neighbourhoods

This paper investigates the effect of commercial land use on the energy and environmental performance of a mixed use neighbourhood. The design variables defining the mixture of various types of commercial buildings, commercial land fraction and floor to area ratio are correlated with different energy and environment related performance parameters. The neighbourhood energy performance is analyzed through various criteria such as energy consumption, PV electricity generation, waste to energy (WtE) generation and ratio of performance, whereas, the environmental performance is evaluated in terms of GHG emissions. A multi-objective optimization study is also carried out to retrieve the optimal combinations of various commercial layout related parameters. The elitist non-dominated sorting genetic algorithm (NSGA-II) and a decision making score (DMS) based selection method are implemented in proposing a generalized commercial land use optimization technique. The key results indicate that for optimal overall performance of the mixed use neighbourhood a number of combinations of commercial buildings can be designed, according to the residential mixtures. For instance, for an equal proportion of housing types, optimal overall performance is achieved by allocating 61% of the commercial area to office buildings, 32% to retail and around 7% to supermarket. The proposed optimization methodology allows multiple combinations of commercial design variables yielding similar performance responses, providing thus flexibility in the design of such neighbourhoods. Considerations of economic factors in the optimization of mixed use neighbourhood design, although not addressed in the current work, are recognized as important issue and proposed for future research.