With around 80% of current UK buildings still expected to be in use by 2050, and as many as four out of five considered energy inefficient, the retrofit market will play a decisive role in achieving Net Zero targets. Improving the performance of existing buildings is no longer optional; it is essential.
According to Gareth Ash, Marketing Manager at Danfoss “active control of energy usage” is a critical pillar in this transition. Delivered through advanced building automation and control (BAC) solutions, it enables buildings to operate more efficiently, reducing both energy consumption and associated emissions.
A key development supporting this shift is the recent update to BS EN 15232, aligned with ISO 52120-1. The revised standard introduces clear, measurable requirements for building performance. Notably, to achieve a Class A efficiency rating, HVAC systems must now incorporate dynamic hydronic balancing.
Why hydronic balancing matters
Hydronic systems distribute heating or cooling via water throughout a building. Effective balancing ensures that the right amount of energy is delivered where and when it is needed. However, in many existing buildings, systems are either unbalanced or poorly balanced, resulting in uneven temperatures, reduced comfort, and unnecessary energy use.
Dynamic hydronic balancing addresses this by continuously adjusting system performance in response to changing demand. Under BS EN 15232, systems must “automatically maintain constant differential pressure across the room temperature control valve, at partial and design flow conditions” to meet Class A requirements. This means both the valve seat and pre-setting must be pressure independent.
Performance under real operating conditions
Crucially, the updated standard recognises that HVAC systems rarely operate at full design capacity. As Gareth explains, “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 risk wasting energy and failing to maintain comfort levels”.
By ensuring systems remain dynamically balanced even at partial load, the standard promotes more realistic and effective energy management. The result is consistent comfort across all zones and significantly improved efficiency. This is particularly important as low carbon heating systems, such as heat pumps, become more widely adopted, where effective hydronic balancing plays a key role in improving Seasonal Coefficient of Performance (SCOP). Studies indicate that true dynamic hydronic balancing can deliver heat energy savings of between 11% and 22%.
The case for Class A performance
Achieving Class A BAC performance, rather than the minimum Class C, offers substantial benefits, particularly in commercial and public buildings with HVAC outputs exceeding 180 kW. Industry estimates suggest that upgrading to Class A systems could deliver £16.9 billion in energy savings and reduce emissions by 39.6 MtCO₂e by 2040.
At a building level, the gains are equally compelling. Moving from Class C to Class A can deliver energy savings of up to 39% in office environments and up to 49% in shopping centres.
Delivering dynamic balancing in practice
For precise temperature control on radiators, solutions such as Danfoss’s ‘True Dynamic’ RA-DV and VHS-DV valves are ideal. They combine a thermostatic radiator valve with an integrated differential pressure controller, providing accurate temperature regulation and automatic hydronic balancing within a compact unit, enabling systems to achieve Class A standards.
When it comes to larger terminal units, such as fan coil or air handling units, the Danfoss AB-QM pressure independent balancing and control valves (PIBCV) can be used. To unlock the highest levels of performance and meet BAC Class A energy standards, the AB-QM is paired with NovoCon digital actuator.
This powerful combination provides exceptionally precise hydronic control and seamless BMS integration. The result is a fully controlled and automatically balanced system that ensures optimised efficiency and simplifies commissioning.
A retrofit opportunity not to be missed
The UK government recently confirmed that emissions are now 50.4% lower than 1990 levels, highlighting continued progress, but also making clear that “meeting the UK’s emissions targets is achievable but relies on urgent action in several critical areas”. Among these are scaling up heat pump deployment and introducing a comprehensive programme to decarbonise public-sector buildings. In this context, hydronic balancing, through the adoption of dynamic valves, represents a practical and proven route to unlocking significant energy savings and reducing emissions across existing building stock.
For building owners and operators, the message is clear: improving efficiency is not just about installing new technologies, but about ensuring systems operate optimally under real-world conditions. When renovating existing buildings, different technical measures can be implemented as part of a staged approach. There is often a dilemma over where to prioritise investment, whether to upgrade the building envelope, replace the heat source, or invest in the building’s technical systems. In reality, there is no one-size-fits-all solution. However, investing in BACS consistently stands out as a highly effective option, offering relatively low capital expenditure compared to other measures, alongside strong returns on investment and short payback periods. As highlighted in eu.bac reports, many BACS investments pay for themselves in less than two years, freeing up financial resources that can then be reinvested into further energy efficiency improvements.
With standards continuing to raise the bar, those who adopt smarter, dynamically balanced systems are best positioned to achieve meaningful, long-term gains, both economically and environmentally.
