Building energy performance assessment through simplified models: application of the ISO 13790 quasi-steady state method

“Energy performance of buildings” estensive international research activities have been carried out on the elaboration and adoption of standards containing common methodologies for building energy performance assessment. One important item concerns the definition of a simplified method for the calculation of energy use for space heating and cooling (ISO/FDIS 13790). A simplified quasi-steady state calculation method is presented in this standard. A further validation is needed to apply this method to different building typologies and to different climatic conditions, and this should include comparison with detailed simulations as well as the analysis of different case studies. The results of a research activity that has been concentrated on the validation of this simplified quasi-steady state method, is presented in this paper. The analyses showed that the accuracy of the results is affected to a great extent by calculation assumptions, boundary conditions and input values, which should be carefully specified.