Disaggregating Cooling Energy Use of Commercial Buildings Into Sensible and Latent Fractions From Whole-Building Monitored Data: Methodology and Advantages

Abstract

In hot and humid climates, where summers are both warm and humid, the latent cooling can be a significant portion of the total cooling load (as much as 40%). Typically the monitored data only includes whole-building heating and cooling energy use and total electric consumption. A method to disaggregate the latent cooling energy use from the measured whole-building heating and cooling energy use would be of particular interest. This paper presents such a method and discusses its benefits. It is shown that the overall heat transfer coefficient including the conduction, infiltration, and ventilation effects of a building, can be evaluated. Subsequently this enables the disaggregation of the total cooling energy use into sensible and latent cooling fractions. The benefits of such a method include: (i) better understanding of the sensible and latent fractions in the total cooling energy use of a building, and (ii) better regression models for energy analysis. In addition to the whole-building cooling and heating energy use and the ambient conditions, the required system parameters include: (i) cold deck supply temperature, (ii) hot deck supply temperature, (iii) mixed air temperature or ventilation rate, (iv) internal gains, and (v) total mass flow rate of the dual duct constant volume system. If continuous measurements of the system parameters are not available, then one-time measurements may be used to disaggregate the latent cooling energy use.