C. Culp

Uncalibrated Building Energy Simulation Modeling Results

Uncalibrated simulations have provided useful data but often with questionable accuracy. For this study, a protocol was developed for performing the uncalibrated simulations and then applied to four buildings for which consumption data were available. The protocol implementation involved using two levels, which allowed a total of 40 hours to survey the building, read the as-built information, and build the DOE-2.1E input file. The consumption data were not available to the simulation engineer until after the uncalibrated simulations were completed. The discrepancies between the simulated and measured total yearly building energy use varied over ±30% with one outlier. The results show that discrepancies ranged over ±90% between the simulations and the measured data for individual components such as chilled water, hot water, and electricity consumption. Although the small sample size limits the overall conclusions that can be drawn, this study shows that uncalibrated simulations can have very low accuracy in predicting the energy use in a building. This study shows the need for calibration when energy use will be used for financial decisions. Uncalibrated models, however, may be quite useful for determining trade-offs between various equipment or building scenarios.

Is Commissioning Once Enough

ABSTRACT Over the last decade, the Energy Systems Laboratory has developed a commissioning process called Continuous Commissioning®. This process is used to resolve operating problems, improve comfort, optimize energy use, and sometimes to recommend retrofits. The process has produced average energy savings of about 20 percent without significant capital investment in over 150 large buildings in which it has been implemented. Payback has virtually always been under 3 years, with two years or less in most buildings. This article describes the process and presents a case study that explicitly shows the value of follow-up consumption tracking and commissioning. Examination of 20 building-years of heating and cooling consumption data from commissioned buildings found an overall increase in heating and cooling of 12.1 percent over two years. Almost 75 percent of this increase was caused by significant component failures and/or control changes that did not compromise comfort, but caused large changes in consump...

Chapter 6 Heating, Ventilating, and Air-Conditioning Control Systems

Texas A&M University 11.