Upgrading a building's heating and cooling controls, particularly through hydronic balancing is a highly effective way to save significant energy (15-38%) with a quick return on investment. The new ISO 16484-4:2025 standard specifies how to implement these systems effectively. According to the standard, only systems that combine modulating room control, occupancy-based demand management, and dynamic hydronic balancing qualify for Class A. Conventional static or flow-limiting valves cannot reach this level. In contrast, Danfoss dynamic balancing valves (RA-DV), designed with the membrane principle, meet all Class A requirements by ensuring true dynamic flow control and high energy efficiency.
In August 2025, the industry published a new standard, ISO 16484-4, providing a precise definition of what constitutes a dynamically balanced system.
Ever since the ISO 52120-1 standard was introduced in 2021, the HVAC industry has grappled with a singular question: What does it mean to have a dynamically balanced system?
The new standard, ISO 16484-4, which the industry published in August 2025, provides the definitive answer to that question. According to the standard, a system must “automatically maintain constant differential pressure across the room temperature control valve, at partial and design flow conditions” to achieve a Class A efficiency rating. This means that both the valve seat and the pre-setting must be pressure independent for the system to be considered dynamically balanced.
According to Tina Krogh Vassard, Senior Product Manager, Hydronics at Danfoss Climate Solutions, the new standard is a welcome clarification for the industry.
Ever since the ISO 52120-1 standard was published in 2021, we’ve been pushing for clarity on what can be considered dynamic balancing. And this new standard finally distinguishes between true pressure-independent valves and simple flow limiters when it comes to dynamic balancing.”
By stipulating that a dynamically balanced system must maintain this state even at partial flow conditions, the new ISO standard ensures that Class A systems use the most energy-efficient approaches to heating and cooling, as Niels Gregersen points out. “Heating and cooling systems rarely operate at design flow conditions 100% of the time. If the system doesn’t account for partial flow conditions, you still risk having a heating or cooling system that wastes energy and doesn’t provide adequate comfort levels for building occupants,” he explains. “Now, under the new standard, building owners who want to achieve a Class A rating, will get a heating or cooling system that maintains a suitable temperature in all rooms at all load conditions.” Studies also suggest that building owners can achieve between 11-22% in heat energy savings by implementing true dynamic hydronic balancing1.
Under the new standard, both the RA-DV and VHS-DV radiator valves from Danfoss are BAC Efficiency Class A compliant.
1 20210322_eubac_System_Balancing_for_TBS.pdf
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