Cardiff Metropolitan University’s ‘Halve the Half’ initiative is cutting estate energy costs significantly, freeing up capital and accelerating progress towards net zero. In the last academic year alone, the University saved over £1m through reduced consumption and improved tariffs. Alongside earlier work on space utilisation, this approach has earned national recognition and continues to reveal further opportunities. Its experience shows how disciplined, data-led estate management can unlock hidden potential in existing buildings – with lessons for clients and construction professionals across the UK.

Energy pressure, competing demands, and a persistent myth

Energy costs in the UK remain volatile, electricity networks are under increasing strain, and building owners face mounting pressure to decarbonise. At the same time, estates teams must address condition, compliance, accessibility, business continuity and user expectations, often with limited budgets and constrained skills capacity.

For many organisations, these pressures appear to be converging faster than practical solutions can keep up as buildings and infrastructure continue to age. A persistent belief has taken hold that decarbonisation inevitably means larger plant, longer programmes and higher bills – particularly once grid constraints and standing charges are factored in. That conclusion is understandable where projects default to like-for-like replacement, or where design decisions are made before real demand is properly understood.

Cardiff Metropolitan University’s experience challenges that assumption. Its results show that when decarbonisation is grounded in measured demand and right-sized engineering, it can reduce cost and risk rather than increase them.

A success worth celebrating – and learning from

The award-winning¹ Halve the Half initiative, led by CIOB Client Champion Graham Lewis, provides a compelling counter-example to claims that net zero is unaffordable or economically damaging. It demonstrates how a disciplined, data-led approach can cut carbon, reduce operating costs and manage grid risk without compromising building quality or user experience.

This is not a story of past failure being corrected. Benchmarking showed that Cardiff Met was already performing well against sector norms, with energy use intensity figures below average. Instead, Halve the Half reveals the hidden potential that can still exist even in estates regarded as efficient – potential that becomes visible when energy use is examined in more detail.

The assumption that quietly drives long-term cost

Many construction and refurbishment projects inherit conservative assumptions about energy demand. Design standards require engineers to size plant for worst-case scenarios, assuming peak occupancy and extreme external conditions simultaneously. These assumptions are necessary to manage professional risk, particularly in early design stages when information is incomplete.

As designs move through procurement, each party understandably errs on the side of caution. Over time, this compounds. Plant becomes oversized, distribution systems expand, and grid connections are specified to meet peaks that may never materialise.

As Lewis explains: “The plant ends up oversized, so more space is needed. Distribution is larger than necessary. Grid connections are sized to peaks that won’t occur, and clients commit to long-term charges that can last decades – often for capacity they never actually use.”

This matters more than ever. Electricity bills increasingly comprise fixed and capacity-based charges linked to maximum permitted demand, not just energy consumed. As networks invest to support electrification, these non-commodity charges are rising sharply. 

What distinguishes Cardiff Met’s approach is that it addressed operational inefficiencies before designing replacements – ensuring that future investment did not replicate historic patterns of waste.

A simple question with wide-ranging implications

Detailed analysis of half-hourly energy data revealed a striking pattern across the University’s estate: around half of total energy consumption occurred outside core working hours (Monday to Friday, 7am–7pm), when most buildings were lightly used or largely empty.

This insight prompted a simple question: if half our energy is used out of hours, how much of that is genuinely needed – and could we halve that half?

The idea was not to reduce comfort or compromise activity. It was about aligning building operation with actual use. Similar patterns exist across many estates, but they are often hidden within aggregated bills and annual benchmarks.

Research into the building performance gap shows that in-use energy demand can be several times higher than predicted at design stage. Even high-performing buildings display wide variation. Halve the Half turned this well-known but poorly interrogated issue into a strategic opportunity.

Data before design – and results that speak for themselves

Rather than starting with new technology or capital projects, the estates team focused on how buildings were actually operating. Using half-hourly meter data and straightforward monitoring, they reviewed schedules, controls and system behaviour, identifying faults and misalignment with real patterns of use.

This methodical work delivered significant results. In 2025 compared with 2023, Cardiff Met achieved:

• a 34% reduction in gas consumption
• a 10% reduction in electricity use
• an 20% reduction in water consumption

In the last academic year, Utility cost savings exceeded £700,000 vs budget and over £1m on a year-on-year basis, with gas spend halved.

Crucially, these savings created financial headroom and organisational confidence. They funded further technical studies, enabled physical interventions, and allowed the team to expand its capacity – all while delivering immediate revenue savings at a time of sector-wide financial pressure.

Applying the same principles to the hardest buildings

Attention has now turned to the University’s most challenging asset: the Cyncoed campus swimming pool and sports centre. This valuable facility supports thousands of children in the community and students, but combines high continuous heat demand with ageing fabric and plant.

Rather than defaulting to oversized replacement systems “just in case”, the same data-led approach has been applied. Typical demand, sustained peaks and short spikes have been separated, allowing new systems to be sized around actual need rather than historic quirks.

This work has unlocked £6.2m of low-interest funding through the Welsh Government’s Digarbon scheme, with technical studies funded from earlier energy savings. By reducing demand first, Cardiff Met can specify smaller plant, avoid costly grid reinforcement and make use of existing capacity headroom created by historic over-provision.

The strategy is reinforced through rooftop solar, behind-the-meter distribution and battery storage, reducing exposure to peak grid costs and high-carbon periods. Once complete, grid consumption at the Cyncoed campus is projected to fall by over 49%, converting the University’s highest-energy building to all-electric systems while reducing pressure on the local network.

Recognition of strategic maturity

National awards have recognised the initiative’s environmental leadership and intelligent use of technology. These matter not for prestige alone, but because they highlight a particular kind of professional judgement: the ability to uncover hidden potential where inefficiency has long been accepted as background noise – especially when professional consultants are empowered to do the right thing.

As Lewis observes, “Too often, net-zero costs are conflated with business-as-usual replacement costs. All plant requires a replacement strategy. Our responsibility is to ensure replacements only provide what is actually needed. Optimising existing buildings is not a second-best alternative to capital investment: it is the foundation that allows future investment to be delivered efficiently, affordably and with confidence.”

Why this matters beyond a university campus

For commercial estate owners, the lessons are directly transferable. Grid capacity is now a strategic constraint. Connection delays affect programme certainty and asset value. Overstated demand locks organisations into long-term costs that are hard to unwind.

Peak demand, not annual consumption, drives network stress. Short spikes often matter more than steady use, and they can frequently be managed through controls, sequencing or short-term storage rather than permanent infrastructure upgrades.

This does not eliminate uncertainty or the need for investment, but it shifts control back towards clients and their professional teams.

The role of construction managers

Successes like Halve the Half depend on coordinated professional input across briefing, design, delivery and operation. Construction managers such as CIOB Chartered Companies have a critical role in revealing these opportunities.

That includes challenging inherited assumptions, ensuring buildings are properly optimised before replacement, addressing grid strategy early, and keeping operational performance in view throughout the asset lifecycle. In this context, construction management is not is about the stewardship of cost, risk, carbon and performance. Cardiff Met is more likely to enter into long-term partnerships with construction businesses who understand that, Lewis notes. 

Celebrating success – and raising expectations

Cardiff Met’s Halve the Half initiative deserves celebration. It shows that estates can cut carbon, reduce cost and manage grid risk through disciplined, data-led decision-making, often before major capital spending begins.

More importantly, it raises expectations. If such gains are possible in an estate with relatively few modern buildings, why should this approach remain the exception?

Analysis suggests that out-of-hours energy use is widespread across sectors. The opportunity now is to embed this way of thinking into everyday practice and design norms. Cardiff Met is already working with partners² across the public and charitable sectors to develop benchmarks and evidence that allow designers to take a more pragmatic, data-informed approach without increasing professional risk.

If awards help shine a light on this hidden potential and encourage others to follow, they do more than recognise success. They help move the industry forward.

Lewis encourages clients, construction managers and consultants (from the private sector as well as the public sector) who want to explore this approach in their own estates to engage with Cardiff Met and the growing collaborative work emerging from this initiative.

FOOTNOTE 1: To date, the Halve the Half initiative has won ‘Outstanding Contribution to Environmental Leadership’ at the Times Higher Education Awards and ‘Best Use of Technology: Carbon Reduction in Construction and Management’ at the Construction News TechFest 2025 awards. It has also been shortlisted in three categories in the Digital Construction Awards.

FOOTNOTE 2: The partners include the Welsh Government Energy Service, CIOB, CIBSE, OFWAT, The Energy Consortium, Energy Sparks and 11 other universities.