Measurement data analysis for heat balance of air-conditioning system in actual office space

Abstract

Research on net-zero energy buildings (nZEB), is currently increasing. To realize a ZEB, it is important to develop a control system for air conditioners and ventilators. This research aims to construct a simulator for office air conditioning to evaluate system control technology.Generally, more than two air conditioning systems are installed in offices, and the cooling operations of each are influenced by the other system’s operation status. To realize a simulator that can capture this effect, we take into account the building envelope, fluid dynamics, and actual system controls. The cooling load and capacity from every source should be balanced in a steady state; thus, obtaining experimental data within a certain error is critical to simulate the power consumption of office cooling precisely.The purpose of this experiment is to analyze the heat balance between the measured cooling load and cooling capacity evaluated from the change in a) inlet and outlet air enthalpy of the air conditioners, and b) enthalpy of the refrigerant.A measurement in an actual office is carried out to study space cooling considering the building environment, office layout (e.g., desks), electricity consumption by computers and lighting, and cooling operation status of the air-conditioning systems. Temperature/humidity sensors, electric-power meters, and several other types of sensors are installed. The office is located on the top floor of a four-story building completed in 1997. The air-conditioning system consists of two VRF outdoor units with a cooling capacity of 28 kW, with six indoor units for perimeter and interior, respectively, and a total of 1600m3/h ventilation flow with the ventilator units.Good heat balance is observed with errors within 10% between the measured cooling load and a), and 15% between measured cooling load and b).