More than a decade ago, there was a growing realisation that while Part L of the Building Regulations provided an important benchmark for performance, compliance tools often fell short of predicting how a building would perform once occupied.
This led to CIBSE introducing TM54 in 2013, an assessment methodology created to bridge the gap between design intent and operational reality. Not only does it provide a vigorous framework for estimating operational efficiency at the design stage of buildings, but it can identify the underlying factors causing any ‘performance gap.’
To do this means not just evaluating regulated loads such as heating, cooling and lighting, but expanding the assessment to unregulated energy use including plug loads, lifts and catering equipment. By undertaking this wider compressive audit, designers, engineers and clients can more fully understand the true energy demands of a building.
Heating systems: a central focus
Among the various energy uses that TM54 brings into sharper focus is that of heating systems, which accounts for a significant proportion of energy use in both domestic and non-domestic buildings. Clearly, running costs are an important factor in the UK, as the cost of energy is far higher than many other parts of Europe.
A key aspect of TM54 is that it encourages designers to go beyond theoretical system efficiencies by exploring how heating systems will perform in operation. For example, it will consider how boilers behave under part-load conditions, how heat is distributed across zones, and whether systems are likely to be oversized or poorly controlled.
It is important that a system design takes into consideration real patterns of use and occupancy and not just design solely for peak heating demand. This involves rethinking existing assumptions about run times, heating schedules, and how different components like radiators, underfloor heating, and thermostatic controls work together. It also facilitates the adoption of low-carbon technologies, such as air source heat pumps, by offering a more accurate projection of their performance under diverse load conditions.
The importance of water quality
Closely tied to heating performance is the often-overlooked issue of water quality. In hydronic heating systems, the condition of circulating water can have a dramatic effect on overall system efficiency. Sludge, limescale, and corrosion not only reduce thermal transfer but can also lead to blockages, premature component failure, and inefficient boiler cycling.
When specifying equipment such as dirt separators, deaerators, and vacuum degassers in heating, cooling, and process systems, careful consideration is needed to ensure optimal performance, efficiency, and system longevity. These components play a vital role in maintaining the quality and stability of water-based systems and under-specifying them can lead to significant operational and maintenance challenges.
Spirotech’s technical team endeavours to be involved at the specification stage of a project. However, this doesn’t always happen or is possible. Consequently, these technical advisors are often brought in as ‘problem-solvers’, following a system breakdown or a poorly functioning one. All too often, they find the wrong products have been installed or fitted on the wrong side of a boiler system for example.
Under-specifying key components can compromise their ability to maintain deaeration, which in turn leads to the accumulation of air pockets, noise in pipework, and inefficient operation. Moreover, oxygen-rich water accelerates internal corrosion of metal components, potentially leading to leaks, system contamination, and costly repairs.
Excess air can lead to several problems including air locks that restrict flow, increased corrosion rates due to oxygen, and cavitation in pumps. Deaerators typically remove microbubbles and free air, while vacuum degassers are more effective at extracting dissolved gases, especially in high-performance or sealed systems.
Spirotech manufactures a range of deaerators and vacuum degassers that serve the essential function of removing dissolved gases, particularly air and oxygen, from the system. This includes the SpiroVent Superior S400 vacuum degasser, which operates at pressures of between 1 and 4 bar – removing all gases, free air, microbubbles and dissolved gases. A smaller model is the S250, an efficient product used in closed heating, cooling and process systems with a pressure between 0.5 bar and 2.5 bar. The largest capacity vacuum degasser in the Spirotech range is the S600, which is applicable for systems with pressures between 2.5 and 10 bar.
Dirt separators are designed to remove debris and particulates from water circuits, but if undersized it may not effectively handle the flow rate or volume of contaminants. This can lead to blockages, increased wear on pumps and valves, and reduced heat transfer efficiency in heat exchangers. Over time, this can result in frequent maintenance, unexpected downtime, and a shortened lifespan of critical components.
Key considerations when specifying this equipment include system volume, flow rate, pressure and temperature conditions, fluid type, and specific application requirements (e.g., HVAC, industrial process, or renewable energy systems). It is also important to account for future scalability or operational load variations.
Inadequate specification often stems from cost-cutting or lack of understanding, but the long-term consequences can far outweigh initial savings. Selecting appropriately sized and rated equipment ensures reliable operation, energy efficiency, and reduced lifecycle costs. Consulting with manufacturers or specialists early in the design phase can help tailor solutions to the application, ensuring that the system remains robust, efficient, and protected against common waterborne issues.
Occupancy and real-world use
TM54 encourages a holistic view of building services, which includes maintaining high standards for water quality from installation through to operation. This means specifying proper filtration and dosing equipment, planning for ongoing maintenance, and monitoring for signs of degradation.
In hydronic heating systems, the condition of circulating water can have a dramatic effect on overall system efficiency. Sludge, limescale, and corrosion not only reduce thermal transfer but can also lead to blockages, premature component failure, and inefficient boiler cycling.
Assessing both the current and future heating requirements of a building is a critical part of the specification process. That’s why involving a water treatment expert from the design stage is essential. Choosing the right equipment from the outset helps avoid costly, time-consuming maintenance and reduces the risk of system shutdowns during future repairs.
As a leading manufacturer of water treatment equipment, Spirotech offers comprehensive technical support throughout every stage of an installation. Our team of experienced technical sales consultants can provide expert guidance during the design phase, helping to prevent serious issues later on and ensuring the system operates at peak efficiency.
With the UK moves closer to its net-zero carbon goals, TM54 will play a pivotal role in ensuring buildings are not only designed with good intentions but also built and operated for lasting performance.