Investigation Of Energy Savings Potential Of Multi-Variable Differential Temperature Control In Economizer

In commercial buildings, building mechanical systems use over 33-50% of the total building energy consumption. As an energy conservation measure, an economizer can be used to reduce energy consumption and operating costs by introducing cold outdoor air into building space based on the outside air temperature or enthalpy. Among control types of economizer, enthalpy-based control is the more energy-efficient approach for the economizer cycle in Korea. However, in reality, humidity sensors are often out of order in buildings, which disables enthalpy-based controls in economizers. Therefore, as a practical substitute, multi-variable temperaturebased control was investigated in this study using the local outdoor air humidity to consider latent loads in the typical temperature-based control and supplement the frequent failures of humidity sensors. The results showed the substantial energy savings potential in temperature-based control, which is driven by reduced system loads in cooling coils in a mixed-humid climate. Also, an analysis of the psychrometric charts represented that the impact of multi-variable temperature-based control would be more significant in humid climates than dry or marine regions. The proposed approach can complement the conventional differential dry-bulb temperature control method and provide a guide for improved economizer operations to achieve better energy performance in hot and humid climates.