Tianjin Metro Depots: Replacing Two Heating Sources with Four Local Energy Stations

Tianjin Metro had two depots with two different legacy heating arrangements. The public project record says Limingzhuang and Caozhuang used municipal heat and gas boilers, with the Limingzhuang depot also using ceiling-mounted gas radiant heaters in part of the train shed. The project was set up to replace both arrangements with electric heat-pump heating.

How the published design was divided

The source lists 21 units at 120 HP and three units at 60 HP, all described as ultra-low-temperature air-source heat pumps. Instead of one central plant, the design used four distributed energy stations. The page states that each station’s water system was designed around its own terminal conditions.

That distribution changes the hydraulic review. Each station has its own pipe route, pump duty, balancing task and commissioning boundary. The published page does not include those calculations, so they should not be reconstructed from the unit count.

Source-reported operating result

The project page states that heating costs could be reduced by approximately 50% after the retrofit and that the change also removed a safety concern associated with the previous radiant heaters. That figure is source-reported; no metering period, tariff assumption or normalized heating-load calculation is published with it.

The transferable lesson is not the percentage. It is the choice to divide a large, mixed depot site into smaller hydraulic zones so that each terminal group can be controlled and balanced on its own terms.