A review on available energy saving strategies for heating, ventilation and air conditioning in underground metro stations

Due to the increasing number of underground metro stations worldwide and the great energy consumption of heating, ventilation and air conditioning (HVAC) systems in underground stations, reducing the HVAC energy consumption while maintaining a hygienic and acceptable environment in underground stations is becoming an ongoing research challenge. This paper presented an overview of the strategies available for HVAC energy saving in underground stations. Firstly, the design features of the HVAC systems are summarized and issues affecting the HVAC systems’ energy efficiency are identified. Then, a thorough review of the energy-efficient HVAC strategies is presented. For each strategy, the principal application and the effect on energy saving are described, and the limitation is also analyzed. Lastly, the strategies are classified and compared from different perspectives and upcoming challenges are proposed. The authors hope that this study can promote the reasonable adoption of different energy-efficient HVAC strategies in underground stations, which could reduce the energy consumption of the HVAC systems in the long run. • Design features of the HVAC system in underground stations are summarized. • Issues affecting HVAC systems' energy efficiency in existing stations are identified. • Various strategies for HVAC energy saving in underground stations are reviewed. • The novel HVAC strategies are classified and compared from different perspectives. • Applicability and upcoming challenges of the HVAC strategies are discussed.