Abstract

Energy characteristics were estimated for an exemplary single-family detached house on the basis of four calculation methods (according to the Directive 2010/31/EU on energy characteristics of detached houses) such as: the method based on the actually consumed amount of energy, the method based on the actually consumed amount of energy calculated for the standard weather conditions and the calculation method compatible with methodology from 2009 with its newest version of 2014 as well. Then the comparison analysis of the method based on the energy actually consumed with the calculation methods for the standard weather conditions was conducted. While comparing needs for final energy for building heating, one can notice a great discrepancy between values of relative errors of estimation. The value of estimation error in comparison with the total energy consumption for heating and preparing hot usable water amounts to 70% if you compare it to the calculation method (according to the methodology of 2014) with the actual energy consumption, whereas 36% if compared to the conversion conditions. The application of calculation models contained in the methodology of 2008 gives better results, because the estimating error is from 38% (compared with the actual energy consumption) to 11% (compared with real consumption taking into consideration the standard conditions). The method used to determine the characteristics will depend on whether the house meets the criteria in rules concerning minimal demands indicating the unit need for initial energy IE max. If the energy characteristics certificate is made on the basis of the method based on the real energy quantity consumption, it will show that a house will fulfill demands, while in the case where energy characteristics will be prepared based on calculation method compatible with the methodology of 2014 the house won’t fulfill demands and it won’t be accepted. If you want to accept as objective the proposed methodology of fulfilling energy certificates, energy characteristics defined on the actual consumed quantity of energy should include a notation of the need to calculate results for the conditions of the standard season.