NET ZERO
Preparing NHS estates for low-carbon heat
Steve Heape, chair of IHEEM’s Environmental and Sustainability Advisory Panel, speaks with Andy Yates of the Carbon and Energy Fund and Rob Hilliard of Vital Energi, drawing on their substantial experience delivering energy, mechanical, and Net Zero infrastructure in operational NHS environments. Together, they explore what trusts can – and should – be doing to prepare existing estates for low-carbon heat technologies, including how early estate preparation and critical backlog investment can be aligned to make future Net Zero solutions deliverable, affordable, and resilient.
As the NHS accelerates its journey towards Net Zero, low-carbon heat technologies are no longer theoretical. Heat pumps, geothermal systems, and low-carbon energy centres now feature regularly in board papers, capital plans, and strategic discussions. Yet those involved in delivering these schemes are increasingly clear about one thing: the success or failure of low-carbon heat rarely hinges on the technology itself. Instead, it is the condition – and readiness – of the
existing estate that determines whether projects succeed, stall, or quietly unravel once the operational realities of live hospitals come into play. “People tend to focus on the technology,” says Andy
Yates, “but the reality is that low-carbon heat will only ever perform as well as the system you’re connecting it to.”
The temperature problem no one can ignore At the heart of most low-carbon heat discussions sits a deceptively simple issue: temperature. “Whatever technology you’re talking about, lower
temperatures make everything easier,” Rob Hilliard explains. “They improve efficiency, reduce energy input, reduce stress on equipment, and give you much more operational flexibility.” Low-carbon heat sources are fundamentally different
from traditional gas boilers. They perform best when supplying heat steadily at lower temperatures, rather than responding to short bursts of high demand. The difficulty is that much of the NHS estate was never designed with this operating philosophy in mind. Many hospitals still rely on high-temperature LTHW
systems – or, in some cases, legacy steam – with flow temperatures of 80–90°C. Those temperatures were historically used to compensate for oversized systems, long distribution runs, and poor insulation, rather than because clinical spaces genuinely required them. “These systems evolved in a very different energy world,” Yates notes. “Cheap gas, high temperatures, constant flow. They worked – but they’re fundamentally
misaligned with where we need to go.” Trying to introduce
low-carbon heat without addressing this mismatch often results in complex hybrid systems, higher capital costs, and disappointing operational performance.
Discovering headroom in existing systems Despite this, both are keen to stress that NHS estates are often more adaptable than expected. “We regularly find
systems that are massively oversized for today’s loads,” Hilliard says. “Radiators, coils, pipework – there’s often far more capacity there than people realise.”
In many cases, hospitals were designed for worst-case winter scenarios that no longer reflect modern building fabric, internal heat gains, warmer winters, or clinical usage. As a result, systems that appear locked into high-temperature operation may in fact have significant untapped headroom.
Simple, carefully managed testing – progressively lowering flow temperatures and monitoring comfort, response times, and complaints – can provide invaluable insight. This approach allows estates teams to understand real-world performance rather than relying solely on historical assumptions or design intent. “We’ve seen sites operate comfortably at 55°C all winter with no complaints at all,” Yates adds. “No new
Servicing engineer using digital tablet.
In many cases, hospitals were designed for worst- case winter scenarios that no longer reflect modern building fabric, internal heat gains, warmer winters, or clinical usage.
May 2026 Health Estate Journal 43
AdobeStock / rh2010
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