The project is to change coal to cleaning energy, which is located in Gansu Province, with an annual minimum temperature of -32℃. The first phase of the project covers the construction area of about 290000 m2, of which 210000 M2 are residents and the rest 80000 M2 are not. The project is divided into four heating stations to provide multi-source clean heating sources with ultra-low ambient temperature double-stage screw air source heat pump, solar energy collection system and heat storage system etc. The actual outdoor air temperature is -17℃～-18℃, indoor temperature is 19℃ ~ 24℃. The ultra-low temperature air source screw heat pump of this project adopts 28 units of Hanbell two-stage ultra-low ambient temperature heat pump LT-S-83/41-A.