Uncertainty of energy consumption assessment of domestic buildings

In order to assess the influence of energy reduction initiatives, to determine the expected annual cost, to calculate life cycle cost, emission impact, etc. it is crucial to be able to assess the energy consumption reasonably accurate.  The present work undertakes a theoretical and empirical study of the uncertainty of energy consumption assessment of domestic buildings. The calculated energy consumption of a number of almost identical domestic buildings in Denmark is compared with the measured energy consumption. Furthermore, the uncertainty is determined by means of stochastic modelling based on input distributions found by literature study, industry guidelines, measurements and – when necessary – simple assumptions. A number of parameters are investigated and ranked in terms of importance to determine which ones contribute the most to the overall level of uncertainty. Measurements and simulations are found to correspond reasonably well; however, it is also found that significant differences may occur between calculated and measured energy consumption due to the spread and due to the fact that the result can only be determined with a certain probability. It is found that occupants’ behaviour is the major contributor to the variance of the energy consumption.