Evaluation of the accuracy of the implementation of dynamic effects in the quasi steady-state calculation method for school buildings

• The accuracy of the quasi steady-state calculation method is evaluated for schools.
• Characteristics of schools are considered while adapting the utilization factor.
• Better results found for the heating need using the adapted utilization factor.
• Quasi steady-state calculation method remains questionable.

The quasi steady-state calculation method (based on EN ISO 13790) is commonly used for energy performance checking. This method attempts to accurately represent the building's energy use. However, intermodal comparison of dynamic and static calculations reveals quite some discrepancies often caused by the inaccuracy of the gain utilization factor and the temperature setback approach used for intermittently heated buildings. This paper tries to improve the method for schools buildings focusing on the gain utilization factor ηH,gn and the parameters a0 and τ0 in particular. These parameters will be adapted to the Flemish climate and the typical characteristics of school buildings. The Monte Carlo analysis technique is applied to cover the broad spectrum of influential parameters. Based on the comparison of dynamic and static calculation results, a regression analysis is performed to determine the correlation between the heat-balance ratio γH and the gain utilization factor ηH,gn. Although more accurate results are found using the adapted dynamic parameters a0 = 1.4 and τ0 = 185, the quasi steady-state method for school buildings remains unreliable as the accuracy of the method is simultaneously determined by the value of the gain utilization factor and by the assessment of the adjusted set-point temperature.