Study of the Outside Air Enthalpy Effects in the Screening of Metered Building Energy Data

Abstract

The energy consumption in a building is affected by many parameters including the occupancy, equipment, schedule time, HVAC systems and outside environment conditions. Currently, the outside air dry-bulb temperature (TOA) is the primary variable used in the data driven analysis for building energy use, including development of energy consumption models and measurement of savings. The measured building energy data analysis based on the variable of TOA has the drawback of overlooking several effects such as humidity, wind and solar. The application of outside air enthalpy (hOA) on a methodology name as “Energy Balance” for screening building energy data to study the influence of outside air humidity on building energy analysis has been presented in this paper. The variable of hOA has been implemented in a developed screening tool, which is the application of first law energy balance, to analyze the building energy use. The energy balance load (EBL) for a whole building, which is the difference between the heating requirements plus the electric gain and the cooling load, has been presented by the two variables of hOA and TOA, respectively. A design of experiment process is conducted to study the linear relations for the EBL as the function of hOA and as the function of TOA. The comparison results lead the conclusion that the EBL in the high temperature range could be better presented with the application of hOA instead of TOA. The energy analysis for buildings located in hot and humid climate would be better performed by using hOA. Study cases are also presented to illustrate the difference between application of hOA and TOA in energy use data analysis for buildings with different functions. The statistics study shows that the energy use analysis for buildings classified as laboratory would be improved in the application of hOA as the variable instead of TOA.