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SONGZ reported 40,151 bus HVAC deliveries in 2025, with electric heat pump systems accounting for 30,394 units, or 75% of total volume. The figures were released around Bus2Bus Berlin 2026 and reported by Sustainable Bus.
The data reflects the continued shift from diesel driven bus air conditioning toward electric thermal management systems, particularly for zero emission city and intercity buses. According to the reported figures, SONGZ delivered 9,757 diesel driven bus AC units in 2025, while electric systems represented the majority of its bus HVAC output.
From 1998 to 2025, SONGZ reports cumulative global deliveries of more than 761,000 bus air conditioning units, including over 307,195 all electric HVAC products. The company previously reached a peak annual output of 60,356 bus AC units in 2017.
The company has also highlighted several developments linked to low GWP refrigerants. These include R1234yf electric AC systems for European applications, a dedicated R744 CO₂ transcritical bus HVAC production line that started operation in May 2026, and an R290 prototype currently undergoing testing.
The LMD rooftop electric HVAC platform has also received Volvo EV Chassis HVAC Compatibility Certificate for use on Volvo’s 8 to 12 metre electric bus chassis. The system supports integrated battery thermal management, ultra low temperature heat pump operation, motor cooling and waste heat recovery.
By the end of 2025, SONGZ reports that the LMD series had reached more than 50,000 installed units globally. The platform is positioned for electric bus applications where passenger climate control, battery temperature management and drivetrain thermal efficiency are increasingly connected.
SONGZ also obtained ISO/SAE 21434:2021 Road Vehicles Cybersecurity Engineering certification in June 2024, adding a compliance element to its electric thermal management portfolio.
For bus OEMs and operators, the reported figures underline the growing importance of electric HVAC systems as part of zero emission vehicle design. Heat pumps, battery thermal management, low GWP refrigerants and chassis compatibility are becoming key factors in bus procurement and platform integration.
