Building on Experience: Five Lessons from CF21 for CF25

Between 2021 and 2025, the Department for Education’s Construction Framework 2021 (CF21) governed procurement of new-build and refurbishment projects across England’s schools, colleges and university technical colleges. Its successor, CF25, is now in place — the question is what CF21’s lessons mean in practice, and where the watchpoints now sit for teams delivering under the new framework.

CF25 is no clean break. It is instead a direct, evidence-led evolution of CF21. The new framework brings a more consolidated approach to technical guidance, alongside greater emphasis on lower-carbon buildings, repeatable design solutions and coordinated delivery. But the measure of its success will be what happens on real projects: how teams respond to individual sites, deliver reliable performance and learn from buildings in use.

Drawing on our own extensive experience of delivering schools under CF21, alongside post-occupancy evaluation (POE) and early results from the DfE’s GenZero pathfinder programme, here are five lessons that can help contractors, designers and supply chain partners turn the framework’s ambitions into better education environments.

What we’ve learned

Under CF21, design teams had to cross-reference a Generic Design Brief and several standalone Technical Annexes to build a full compliance picture. CF25 consolidates these into a single Technical Manual and Pattern Book and is noticeably more prescriptive: rules of assembly, new model designs and standardised spatial arrangements now set a clearer baseline for every project.

We have seen the value of this first-hand through our work for the DfE on Northumberland College, one of the GenZero pathfinders testing these repeatable planning models in live conditions. Across the programme, standardised prototype designs achieved embodied carbon performance below current LETI best-practice benchmarks. Repeatability takes out guesswork, and it is ultimately how these projects will be delivered at the pace needed to renew England’s education estate.

Why it matters

Known components and construction sequences reduce design development time and pricing risk, suit offsite manufacture and make performance easier to track from one project to the next. But a more prescriptive framework also means fewer design decisions are left open, so the ones that remain carry more weight.

Every school sits on a different site, serves a different community and supports a different way of teaching. Orientation, daylight, views, external space and local identity still shape how a building feels to learn and work in every day, and standard components won’t resolve these on their own. This is where thoughtful design adds most value: taking a proven kit of parts and shaping it around a particular place and the people who will use it.

What project teams should consider

Work with the Pattern Book’s standardised elements and rules of assembly from the outset, and identify early where the guidance leaves room for a site-specific response: orientation, external space, community context and local identity. Agree the implications for programme, cost and supply chain before those decisions become difficult to change, and use the time standardisation saves to invest in the aspects of a school that should be distinctive.

What we’ve learned

POE research consistently shows that design intent does not automatically translate into performance in use. For the DfE’s GenZero programme, Mott MacDonald, as integrator across 13 partner organisations, evaluated 54 recently completed or refurbished schools through site visits and staff questionnaires, and found the performance gap persisting.

Ventilation is a clear example. Comparative studies of secondary schools found naturally ventilated buildings offered better passive comfort but carried significantly greater overheating risk under future climate projections, while mechanically ventilated buildings were more resilient to overheating but saw procurement and operational shortcomings compromise their energy performance.

Yet as an industry, we rarely see where these gaps are. Headteachers generally lack the institutional incentive to commission evaluation themselves, so without a direct mandate and clear ownership, it is unlikely to happen consistently.

Why it matters

A low-carbon design only works if the building performs as intended once occupied, and a performance gap that is never measured can’t be closed. Construction quality, commissioning, handover and the ability to operate systems properly matter as much as design-stage calculations. With DfE monitoring classroom temperatures through a national overheating risk study since 2022, this is an ongoing risk to manage, not a box to tick at approval.

What project teams should consider

Assess energy use, ventilation and overheating together from the outset. Resource commissioning and soft landings as seriously as design, and be clear who is responsible for performance after occupation. We would go further: POE should become a routine, contractual part of CF25 delivery, built into contractor performance requirements and framework re-appointment criteria, rather than a periodic research exercise run between framework generations.

What we’ve learned

The DfE is leading the way. For the first time, CF25 defines embodied carbon through set targets that become progressively more ambitious over the life of the framework, backed by consistent measurement and reporting. That creates a real opportunity to change how schools are built, and timber is often seen as the obvious answer.

In practice, the picture is more complicated. The regulatory environment around fire test data for timber construction is tightening, and the domestic supply chain can’t yet absorb a large-scale shift to timber-first construction without longer lead times and greater exposure to imports.

Why it matters

A low-carbon solution only delivers value if it can be approved, procured and built on programme. A material choice that stalls at fire sign-off, relies on limited product testing or sits in a long import queue puts at risk the cost and programme certainty CF25 is designed to protect. Timber can offer significant carbon benefits, but it isn’t the answer for every project, and treating it as one risks missing a bigger opportunity.

What project teams should consider

The opportunity is to innovate. Tightening targets give the industry a clear reason to develop alternative low-carbon materials and systems, rather than relying on a single solution. Make sure those solutions are technically robust, compliant and deliverable at scale by testing them early against fire safety requirements, available product test evidence and supply chain capacity, so they can enter the market effectively.

What we’ve learned

GenZero’s POE of 54 schools identified communal and outdoor spaces, alongside light, bright and well-ventilated interiors, as a priority, informed by evidence of mental and physical health benefits for building users. CF25 responds directly: the Pattern Book sets out outdoor space as a distinct typology on the same footing as internal teaching and communal spaces, rather than residual landscaping once the building footprint is fixed.

Our experience shows that the more effort invested in the landscape strategy, the more it gives back to learning. At Langham Oaks, an SEMH school for boys aged 10–16, landscape didn’t sit around the building; it shaped it. The school’s “no boundaries” ethos called for pupils to move freely without compromising safety, so we planned the school around a central courtyard and removed corridors altogether.

That one landscape-led decision did the work of several. The courtyard became circulation, breakout and gathering space in one, gave staff natural passive supervision and opened every classroom directly onto the woodland beyond. Outdoor space now supports the school’s approach to teaching and wellbeing throughout the day, not just at break time.

Why it matters

External spaces support outdoor teaching, play, social development and wellbeing, and for SEND settings they can shape everything from building layout to drop-off, buffer zones and supervision. They also contribute to sustainable drainage, biodiversity net gain and passive cooling, linking back to the overheating risks above. And as internal layouts become more consistent under CF25, landscape is where variation, identity and responsiveness to place can be introduced. Treated as a late-stage addition, these are the first benefits lost when budgets or programmes tighten.

What project teams should consider

Scope, budget and evidence landscape and external works with the same rigour as internal accommodation, and bring landscape designers in from the earliest stages so outdoor space can drive the layout rather than decorate it. Coordinate building orientation, views, shade, access and outdoor learning needs. Treat biophilic and outdoor learning principles as a default across all space types and value bands, not a feature reserved for flagship projects, and protect them during value engineering.

What we’ve learned

We saw this across CF21. It was more prescriptive than the framework before it, and that clearer starting point freed up time. With less effort spent establishing the fundamentals on each project, teams could focus where it made the biggest difference: the site, the brief and the people who would use the building.

CF25 now goes further in this direction. A consolidated Technical Manual, a more prescriptive Pattern Book and mechanisms such as scheme batching, earlier contractor engagement and more streamlined procurement routes are all designed to align teams from the very start. The benefits are real, but only if that alignment and collaboration happen effectively on every project.

Why it matters

Clearer guidance is only as good as the feedback that refines it. Five pathfinders is a narrow sample for a national Pattern Book covering every space type and value band, and embodied carbon targets will become progressively more ambitious through the life of the framework, so feedback from atypical sites and briefs will be essential. The Pattern Book’s twelve-month review cycle creates a route for it, but only if design, construction, manufacturing and operational experience is captured and shared rather than staying within individual project teams.

The same applies commercially. CF25’s six-year term, compared with CF21’s four years, and more repeatable specifications give manufacturers and contractors greater confidence to invest in tooling, production capacity and skills. But those advantages depend on timely direct-award and drawdown decisions, coordinated delivery and a feedback loop that captures what works.

What project teams should consider

Agree shared performance expectations early and involve specialist partners at the right stages. That includes FF&E: under CF25 it sits within sustainability and wellbeing reporting from the outset, so it needs to be resourced and costed at bid stage rather than treated as a late addition, as it often was under CF21. Document lessons in a form others can use and feed live project experience into the Pattern Book’s annual review, including where standard approaches need adaptation. Treat POE and project learning as part of delivery, not an optional exercise after completion.

CF25 provides a more consistent foundation, but consistency alone will not deliver better schools. We must combine proven solutions with sound professional judgement, attention to occupants and an honest assessment of buildings in use.

For contractors and their partners, the practical challenge is to make those conversations happen early enough to influence design, cost, programme and performance. Learning from CF21 should be a continuous process: test what works, share what does not and use that evidence to improve the next project. Compliance is the starting point; better schools come from what teams build on it.