Why HIUs hold the key by Charlie Mowbray, Senior Product Manager, Ideal Heating - Commercial
Universities across the UK are under growing pressure to meet ambitious net-zero targets, manage rising energy bills, and ensure that their estates remain fit for purpose in a highly competitive higher education market. Student accommodation, teaching spaces, laboratories, sports centres, and libraries all require reliable and efficient heating and hot water. This creates a huge challenge for estates teams, particularly at a time when funding is tight and expectations from students and staff are rising.
The benefits of a heat network
Heat networks are increasingly being seen as part of the solution. These systems distribute thermal energy from a central plant to multiple buildings, offering the opportunity to achieve a lower-carbon and often more cost-effective alternative compared to individual boilers or standalone heat pumps attached to each building. When designed and operated well, heat networks can help institutions cut emissions, improve resilience and reduce energy expenditure. Yet many campus heat networks installed ten or more years ago are beginning to fall short of expectations. Ageing infrastructure, outdated technology, and poor system control are all undermining efficiency.
Upgrading heat networks
To support the upgrade of these underperforming systems, the UK government launched the Heat Network Efficiency Scheme (HNES). With £32 million available through 2025, HNES provides grant funding to public, private, and third-sector organisations for refurbishments. While most attention tends to focus on modernising energy centres, the performance of the Heat Interface Units (HIUs) on the network must also be scrutinised, as they are crucial to how heat is delivered and used at the point of use.
HIUs sit at the point where thermal energy from the network is transferred into individual dwellings or ‘clusters’ of dwellings, which can be anything from a small collection of rooms with a communal living area or more localised areas, such as a single floor within a building. The HIU uses heat exchangers to transfer the heat from the distribution network to satisfy the end-users’ heating and/or hot water system needs. The HIU is an efficient method of transferring heat from the network to generate instantaneous hot water or to provide input to low temperature heating systems.
The role of HIUs on campuses
The role of HIUs is particularly important on campuses, where the sheer variety of building types creates very different demands on the system. A laboratory, for example, may need highly stable temperature control, while student accommodation blocks must deliver responsive hot water at peak times, and libraries or lecture theatres require balanced space heating throughout the day. If the HIUs in these settings are outdated or underperforming, the wider system cannot deliver its promised benefits, no matter how advanced the central energy centre may be.
Legacy HIUs and the impact on efficiency
Legacy HIUs, many of which were installed before any formal performance standards were in place, are a hidden source of inefficiency across campuses. Without benchmarks like the BESA HIU Test Regime, early units often struggle to manage temperature control, offer limited adjustability, and are difficult to maintain. In addition, some manufacturers are no longer in business, meaning support and spares are either unavailable or not cost-effective. The consequence can be high return temperatures, which can lead to reduced efficiency of the entire system. Even when the core plant is upgraded, these return temperatures can undermine overall performance.
For universities managing hundreds of units across multiple sites, these inefficiencies multiply into higher energy bills, more service callouts, and rising dissatisfaction among students and staff.
One increasingly popular approach is the replacement of HIUs on a distressed basis—replacing individual units as they fail, rather than undertaking a full-scale retrofit. This can be an efficient use of resources if new HIUs are compatible with the network’s design parameters, including flow and return temperatures and differential pressure.
Choosing modern HIUs for retrofit applications
Modern HIUs, by contrast to legacy equipment, are engineered to control return temperatures more effectively, which can have a direct impact on system efficiency. They also provide better user control, improved hot water responsiveness (an essential factor in student halls where demand can peak sharply in the mornings and evenings), and are often designed for easier installation and ongoing maintenance. While laboratory testing can highlight small performance differences between units, in real-world applications, ease of installation, commissioning and serviceability can be just as critical as technical specifications. Poor commissioning or inaccessible components can negate the benefits of even the most technically capable equipment. Therefore, decisions around HIU selection should consider not only energy performance but also operational usability and long-term support from the manufacturer. Ideal Heating Commercial’s POD HIUs offer a layout that prioritises access and usability, simplifying the installation and maintenance process.
The economics of HIU replacement
The economic case for HIU replacement on university campuses is strong. Although the upfront cost of replacing hundreds of units can appear daunting, the long-term savings often outweigh the initial investment. Poorly performing HIUs drive up energy consumption and generate frequent service requests. By upgrading to modern units, many institutions are seeing measurable efficiency gains, with payback achieved within favourable timescales. Beyond this period, the savings continue for the operational life of the equipment.
Futureproofing through strategic investment
For higher education leaders, upgrading HIUs is more than a technical measure: it is a strategic investment in the long-term resilience of the estate. The direction of travel is clear. Universities are making bold net-zero pledges, students are increasingly vocal about the environmental performance of their campuses, and sustainability is being integrated into league tables and funding frameworks. Heat networks will play an essential role in this transition, but only if every component, from the energy source to the end-user interface, is optimised. By proactively upgrading HIUs, universities can cut emissions, reduce operating costs, improve the reliability of services, and demonstrate visible leadership on climate action. This, in turn, strengthens their appeal to prospective students and staff who are increasingly making choices based on institutional values as well as academic performance.
For estates managers and university leadership teams seeking to modernise their infrastructure, HIU upgrades should not be viewed as an optional expense but as a cornerstone of futureproofing. With government funding available, favourable payback periods, and long-term operational benefits, the case for action is compelling. As universities across the UK move closer to their net-zero deadlines, the conclusion becomes clear: modern HIUs hold the key to unlocking campus efficiency and resilience, helping institutions not only to manage today’s pressures but to prepare for the demands of tomorrow’s low-carbon economy.
Ideal Heating Commercial is the UK’s market leader of high efficiency commercial heating solutions.