Life cycle optimization of extremely low energy dwellings

A global methodology is developed to optimize concepts for extremely low energy dwellings, taking into account energy use, environmental impact, and financial costs over the life cycle of the buildings. Energy simulations are executed with TRNSYS. The ecological impact is evaluated through a life cycle inventory of the whole building, whereas costs are evaluated through a cost-benefit analysis. The multi-objective optimization problem is tackled by combining genetic algorithms and the Pareto concept. First, the optimization methodology is presented. Subsequently, the validity as well as the strengths and weaknesses of the methodology are discussed. Finally, the main results are presented followed by a discussion of the trade-off curves of primary energy consumption and net present value, an analysis of the embodied energy, and a study of the impact of economic parameters, such as price evolutions above inflation and discount rate.