The analysis of enthalpy control strategies and its application in hot and humid climates

Air enthalpy control strategy, or often known as free cooling, has been very effective in conserving building air-conditioning power consumptions-in moderate climatic areas. However, it stands for a challenge on its application in hot and humid areas, such as in Taiwan, where outdoor air enthalpies are constantly high. Three control schemes, namely, those using temperature control (economizer, or T-control), enthalpy control (H-control), and the Modified temperature control (MTcontrol) were studied in this paper. The MT-control method was actually applied on a full-scale energy test house for experimental investigation. Night ventilation in scavenging residual heat gain through building envelope had successfully introduced lower indoor temperature as expected in a typical April day. The simulation result of their annual performances was also validated that enthalpy control strategies have quite limitted application potential in hot and humid areas, especially in the summer when cooling is most needed.