Application of optimisation, building energy simulation and life cycle assessment to the design of an urban project

International audienceThe building sector is the economic sector of the EU that has the highest final energy consumption. In response to concerns about climate change, energy security and social equity, most countries plan to substantially reduce energy demand and greenhouse gas emissions. Moreover, 55 % of the world’s population lives in urban areas, a proportion that is expected to rise to 68 % by 2050. Finally, there are effective catalysts to improve environmental performance at the scale of urban projects. For these reasons, environmental impacts of the neighbourhood have to be minimised using reliable tools offering economically viable solutions. This paper presents a multicriteria optimisation methodology that has been developed to reduce both investment and environmental costs of buildings. The life cycle assessment methodology used in this study enables the evaluation environmental impacts over the whole life cycle of buildings. The optimisation of an individual building and the simultaneous optimisation of several buildings were carried out considering various criteria such as environmental impacts and construction cost, in the case of a 5-hectare urban project. A genetic algorithm was implemented in order to identify Pareto-optimal solutions associating a life cycle assessment tool to building energy simulation. The first step was to implement the NSGA-II algorithm and a comparison with the NSGA-III algorithm is considered in perspective. Results present optimal Pareto fronts minimising investment costs and CO2 emissions of buildings. In this way, a decision-making aid is proposed to urban planners