Use of First Law Energy Balance as a Screening Tool for Building Energy Use Data: Experiences on the Inclusion of Outside Air Enthalpy Variable

Abstract

Quality controlled energy-use data is the foundation of energy performance evaluation for a building. The “Energy Balance Load” (EBL), a parameter derived from the first law of thermodynamics based on a whole-building energy analysis, has been theoretically proved to be an effective tool for verifying whole-building energy-use data (Shao and Claridge, 2006). Quality control methodology using EBL has been proposed and applied to more than one hundred buildings on a large university campus by Baltazar et al. (2007). They picked the outside air dry-bulb temperature (TOA) as the explanatory variable of EBL, and used a plot of EBL versus TOA, called energy balance plot, to find faulty behavior in the data by visually observing the pattern. It has been demonstrated that this methodology can detect significant data problems caused by variety of reasons such as scale factor error and mislabeled meter successfully. This paper presents a possible enhancement on the existent EBL analysis technique by using the outside air enthalpy (hOA) as the explanatory variable of EBL instead of TOA. This enthalpy based analysis accounts for the effect of latent load on EBL, and therefore, may enhance the data screening capability for buildings operated at locations with hot and humid climate. Numerical threshold of data screening proposed by Masuda et al. (2008) has been applied to this enthalpy based methodology to determine the difference in the results of data screening between enthalpy based analysis and temperature based analysis.