This article presents the evaluation and optimization algorithm of the building energy system. Two main objectives have been achieved: the optimal configuration of the building energy system has been defined, which minimizes the use of non-renewable sources and reduces the environmental impact of the building. Energy demand for the house has been simulated employing DesignBuilder software. Five configurations of technologies for the building energy system have been chosen and simulated applying Polysun software in order to define the seasonal energy efficiency of the generators of each configuration. Multi-criteria decision making methods SAW (Simple Additive Weight), COPRAS (COmplex PRoportion ASsessment) and MEW (Multiplicative Exponential Weighting) have been used for finding the optimal decision on this case study.

Article in Lithuanian