Life Cycle Optimization of Extremely Low Energy Buildings

A global methodology is developed to optimize concepts for extremely low energy dwellings, taking into account energy savings, 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 solved with a combination of genetic algorithms and the Pareto-concept. Firstly the optimization methodology is presented. Subsequently the main results are presented and a hierarchy of cost-effective energy saving measures is derived. Finally the impact of economic parameters, such as price evolutions and discount rate is discussed together with the strengths and weaknesses of extremely low energy buildings from an economic point of view.