Experiences internationally and locally shows that if optimization processes are applied sequentially, the optimal and economical design will not be achieved. It is necessary to implement integrated energy design development where both the active and the passive design features are evaluated and optimized in one integrated process, where the objective is to balance active and passive features so that the best energy performance is achieved at the lowest overall investment costs.
Integrated Energy Design is practiced by considering all energy saving possibilities, passive and active, at the same time, and by choosing the combination of measures and specification of the components and systems so that a high energy performance is achieved at the lowest investment costs. This can only be done by utilizing advanced computer simulation programs to analyze the overall and the detailed energy performance as early in the design process as possible through design workshops with all the other consultants in a project. That allows strategic decisions to be taken, such as extra investments to be made in a more energy efficient façade that will be balanced by savings to be made on a reduced size of the ventilation and cooling system, a reduction that can be determined early on in the design process using computer modeling.
Our experience shows that when Integrated Design Optimization is implemented a LEED Gold building typically costs less than 5% extra, and it is a least 5% more valuable. Furthermore the payback time from operational savings is 5 years or less. There are no real extra costs for green buildings, only savings!