Calibration of an Energyplus Simulation Model by the Stem- Pstar Method

The PSTAR (Primary and Secondary Terms Analysis and Renormalization) method was developed by the National Renewable Energy Laboratory (NREL) to determine the key thermal parameters of a building from short-term outdoor test results. This paper shows an application of the PSTAR method as a quantitative guidance to calibrate a detailed thermal model of a dwelling. An existing dwelling sited in southern Spain is used as a case study. The entire process comprises: A) Starting from audit data, a detailed EnergyPlus model of the building is created. B) Some experimental tests are carried out: blower door test, thermographic inspection, determination of thermal resistance of some envelope components using heat flux meters and the STEM (Short Term Energy Monitoring) test procedure. C) The PSTAR method is used to obtain quantitative information about the model ability to reproduce three primary thermal parameters of the actual building: the building heat loss coefficient, the charge/discharge of the building mass coupled with variations of the indoor temperature and the solar gains. D) The EnergyPlus model is reasonably calibrated using all information available. As a result, a calibrated model is obtained, whose performance shows good agreement with measured data, yet some caveats still remain in the calibration process. Finally, some modifications to the STEM test are suggested in order to obtain a better experimental data set.