A study of fresh air control in subway stations

This paper examines the energy consumption problems in the subway station Ventilation and Air-Conditioning (VAC) systems in a typical city, as well as identifying the fresh air-cooling load reduction as a key to energy savings. The two components of the fresh air in the stations, which are “mechanical fresh air” provided by VAC system and “unorganized fresh air” generated by piston effect, are analysed through network simulations and field measurements. The results indicate that the unorganized fresh air is sufficient to meet the demand, except for high-traffic times in the future phase. Based on the discussion, the current VAC systems in most part of China cannot sufficiently control the volume of mechanical fresh air. Accordingly, an improved system with the completely sealed fresh air damper and a matched fresh air controlling method is proposed, and the method is verified by field tests. The study informs the readers about the ways to achieve energy saving in subway stations through the control effective usage of the fresh air.