Architects prioritise retrofit in school buildings in 'fabric first' route to net zero

School leaders’ attention should be focused on their pupils but increasingly it is directed at the flaws and failings of their classrooms. Before concerns about the risks of reinforced autoclaved aerated concrete (RAAC) came to a head this summer, the National Audit Office (NAO) had reported in June how the state of the school estate had declined following ‘years of underinvestment’. The NAO also criticised the lack of progress in decarbonising buildings, with its head, Gareth Davies, saying the Department for Education (DfE) has an ambitious strategy, but ‘no plan for how it will achieve this or how much it is likely to cost’. 

DfE’s school rebuilding programme set a net zero requirement for newbuilds, but there’s no such priority for retrofits. And another funding route in England – the government’s Public Sector Decarbonisation Scheme (PSDS) grant – largely helps replace end-of-life heating systems. As a result, buildings in poor condition may not be having their fabric upgraded and made more energy efficient.

Climate action charity Ashden and funder Green Future Investments are working with DfE to help unlock more innovative finance options, to help schools step up action on retrofit by next summer. ‘That’s incredibly ambitious,’ says Alex Green, head of Ashden’s Let’s Go Zero schools campaign and member of DfE’s user group for its sustainability and climate change strategy. Finance options are likely to combine improved access to existing money with private investment. ‘If we can have more schools take up what’s already available and iron out the barriers, it will prove there’s an investment route for more private and public finance,’ she explains.

Ashden’s campaign has shown schools’ appetite for change, with more than 2300 schools, colleges and nurseries signed up to its ambition. Green says, ‘We’ve found the two biggest barriers to climate action in schools are access to retrofit finance and a lack of expertise in climate action among school leaders, so they’re not confident to take on the funding that does exist.’ In response, Let’s Go Zero and Green Future Investments are also partnering to recruit 30 climate action advisers to work with schools, helping them access funding.

Already benefiting from a PSDS grant is schools group United Learning, which last year won backing to retrofit five academies in north west England, out of nearly 100 schools in its national portfolio. The five will have boilers replaced with air source heat pumps (ASHPs) and upgrades to heating infrastructure and lighting, with some adding insulation and photovoltaics. While the group is match-funding its grant, availability of funding is a constraint in achieving net zero, acknowledges George Stroud, United Learning’s energy manager, but he says, ‘We’re aiming to be frontrunners in the education sector in reducing our carbon emissions’.

Learning through repurposing
‘You have to improve the fabric, then look at the renewables,’ says Claire Mantle, school sector lead at ADP Architecture, advocating this as part of an estates strategy setting out how buildings can be incrementally improved. ‘If we can make the fabric right,’ she continues, ‘a client can get funding or a grant later and put PV on the roof, for example’.

The practice targeted retrofit projects in DfE’s rebuilding programme and has worked on five. ‘None would be net zero carbon in operation, but they’re all creative and some have repurposed buildings, so have been great for embodied carbon,’ says Mantle. They include the listed Victoria Building in Blackburn, a college that will have three lightwells punched into its fabric, roof insulation added and timber windows restored using finned double-glazing units. Another project saw a 12-year-old Sandwell office block converted to create the UK’s first state-funded music school, complete with a theatre formed in its atrium. Shireland CBSO Academy, opened in September, has had minimal interventions made to its fabric. ‘When it comes to retrofit, the priority for net zero carbon is not yet in the DfE framework,’ says Mantle. ‘But DfE is listening.’

The practice is gathering data on its refurbishments to build understanding and make the case for a more strategic approach, but measuring benefits can be far from straightforward. Says Mantle, ‘In theory, a new or refurbished building should be more energy efficient, but then it will have more kit in it, like mechanical ventilation with heat recovery [MVHR] for better air quality and health and wellbeing. So a more energy efficient building might be less expensive to heat, but more expensive to ventilate.'

Then there’s the high retrofit cost for buildings in poor condition. ‘We can’t just keep knocking buildings down. It can’t just be financially driven,’ says Mantle. ‘Yes, the capital cost is going to be more, but we’re improving the thermal envelope, creating a better environment for the longer term – and leaving the school with something that’s easy to maintain and will stand the test of time.’

Finding the balance
Some local authorities are taking a more strategic view like Edinburgh City Council which, having adopted the Passivhaus standard for new schools, sought similar rigour in retrofit. That led it to work with Architype to develop an Enerphit-informed retrofit planning methodology to inform its decarbonisation decisions.

While the approach sets out options for appraisal, ranging from heating decarbonisation to certified Enerphit refurbishment, with potential costs, savings and payback, initial studies are showing the value of a fabric-first approach, says Alex Reeves, senior architect with Architype. ‘Once you model a services-only approach – where you might replace the heating system but don’t make improvements in the performance of the fabric from an energy perspective – operational costs significantly increase,’ he explains. ‘Actual running costs of, for example, an air source heat pump, can be quite considerable if you’re not reducing heat demand, which is what we always aim to do through energy retrofit.’

The practice has so far analysed 12 non-domestic projects in Edinburgh, including nine schools. One Victorian and one post-war school are progressing to pilot projects targeting insulation works, improved airtightness, new windows, ASHPs and MVHR, but not Enerphit certification. ‘Quite often we find that, for clients, the right balance of energy performance and upfront capital cost sits a little bit short of certification,’ says Reeves.

Scottish government policy is helping drive change, notably LEIP, the newbuild Learning Estate Investment Programme with its outcomes-based funding model, jointly funded by government and local authorities. ‘LEIP has opened up the conversation about energy in schools in Scotland, and when you bring energy performance into the conversation, you really need to understand the fabric,’ says Christina Gaiger, associate at Architype.

Many schools still lack that understanding, says Christian Dimbleby, associate at Architype. For too long, authorities and others haven’t invested enough in terms of maintenance and understanding their buildings, he says, adding that RAAC has highlighted longstanding shortcomings that could perhaps be addressed by drawing on the experience of conservation architecture – like quinquennial church inspections. Already, Enerphit-informed options appraisals are starting to change the way the practice works with clients. ‘It’s essentially extending that relationship to encompass and quantitatively understand how the building performs and works for the client and users,’ says Gaiger.

Net zero exemplar
Net zero remains a demanding target however. That’s evident in projects like the upgrade of the 1970s-built Pen Y Dre High School in Merthyr Tydfil, which will be Wales’ first school retrofit to net zero in operation and takes on board government embodied carbon targets. 

The project’s six phases span the school’s linked buildings, with Lawray Architects’ design including enhanced insulation, new cladding and windows. Five design options were appraised, but only one met the target of net zero, based on a whole-life carbon approach over 60 years, which included adopting full electrification with ASHPs and onsite PV. ‘We knew that for a school refurbishment of this nature we’d need to offset energy consumption via an extensive PV array,’ says Mark Morant, director at sustainable design advisor Arda Consulting. ‘While we embraced a fabric-first approach to design, reducing energy consumption to that of a new build is very challenging. 

Initial modelling indicates that the project’s upfront embodied carbon is around 250kg CO₂e/m², within the Welsh government’s 2030 target of 350kg CO₂e/m². ‘That has emphasised the importance of retaining and reusing structure – it’s the biggest single saving,’ says Morant. As for the additions, he continues, ‘The biggest impact by a country mile came from the extensive PV array – which amounted to about 43% of whole-life embodied carbon’.

Ask Morant what broader learning is coming from the project and, alongside collaboration, he returns to common themes: the need to understand the condition of the building, adopt a fabric-first approach to design and understand total energy consumption in operation. ‘Fabric first is fundamental to the entire net zero strategy,’ he says.