In this paper the comparison of using simple genetic algorithm and parallel genetic algorithm is presented. As the optimization problems the parameter setting of the heat transfer model of a building and the building’s model calibration were chosen. The model simulation requires huge computing capacity and it is time consuming. Therefore the pressure of simulation evaluations number is concerned and the use of parallelism is desirable. Genetic algorithms and parallelization were implemented in Matlab and the simulation of heat transfer model, which is the part of the fitness function, is performed in Comsol Multiphysics.