Energy efficiency labeling: Study about the influence of schedule definitions

Technical literature shows that there is a performance gap between a simulated design and the actual building performance, especially given the differences between the post-occupation routines and those provided in the design phase. This paper aims to analyze the differences between the electric energy consumption prediction of a call center building located in Belo Horizonte, Brazil, using (a) a schedule based on routines provided by the air conditioning designer made in order to establish the system loads and to define the system equipment and (b) a schedule based in the employee's routines provided by the owners of the building. First, the simulation results were compared to the mean measured building energy consumption and, differently from the first schedule, when the second schedule was used, a Normalized Mean Bias Error (NMBE) of 5% was met which is considered a prediction acceptable by the ASHRAE Guideline 14-2002 [Measurement of Energy and Demand Savings (American Society of Heating, Refrigerating and Air-conditioning Engineers, 2002)]. Afterwards, it was verified how the two occupation schedules influenced the building classification according to the Brazilian Governmental Building Energy Efficiency Labeling. In this case, the two different schedules resulted in a difference in electric energy consumption of 10.9%, leading to a difference of one level in the classification. This fact clearly demonstrates the importance of a correct definition of occupation and equipment usage in the energy performance prediction of a building.