The current client context
“Sustainability management has historically been treated as a post-design compliance tick-box exercise rather than an overarching design philosophy,” Jennie says.
That legacy can leave clients viewing early sustainability measures as “an extra administrative burden or an added expense rather than a core driver of project value”.
Sustainability can also be defined too narrowly, with attention focused on individual environmental measures rather than whole-life carbon, social value and long-term commercial resilience.
The regulatory landscape can reinforce this. Without explicit requirements compelling private developments to meet strict sustainability targets early, Jennie says, “project teams often default to standard procurement routes unless the client’s corporate culture actively demands otherwise”.
The risk is that sustainability becomes a consideration once decisions on structure, materials and building performance are already difficult or expensive to revisit.
The cost of waiting
By the time a design is advanced, improving building performance can involve significant rework. Airtightness, ventilation and Passivhaus principles are easier to consider as part of the original design than to retrofit once the building fabric and systems are established.
Groundworks provide a practical example. “Once a design is locked into set levels, there is very little flexibility to alter it,” Jennie explains.
If ground levels and cut-and-fill requirements are not properly considered early, changes can result in surplus material being removed from site, adding transport, disposal and cost. Delayed decisions on the building envelope can also mean installing larger renewable energy systems to compensate for heat loss that could have been addressed through design.
These decisions affect both the cost and practicality of delivery. Sustainability performance therefore needs to be considered alongside design, procurement and buildability, rather than treated as a separate exercise.
Considering carbon and cost together
Early contractor involvement gives project teams the opportunity to assess these factors before specifications are fixed. Jennie advocates managing carbon budgets alongside financial cost plans, using tools such as OneClick LCA to compare options while there is still time to change them.
Early supply-chain engagement can also help teams assess alternative materials, circular products and opportunities for reuse before procurement decisions are settled. It can reduce the risk of sustainable material choices being rejected late in the process because of availability, compatibility, cost or technical requirements.
At Greenstone Primary School in Coalville, early carbon assessment informed material choices during pre-construction. Stepnell worked alongside Harworth Group, Lungfish Architects and CarbonLEAF at the University of Lincoln to assess the scheme’s embodied carbon.
Changes to the concrete specification saved 100 tonnes of carbon dioxide equivalent (tCO₂e), while UK-manufactured offsite i-FAST timber Structural Insulated Panels (SIPs) were reported to sequester 134.2 tCO₂e. The scheme’s upfront embodied carbon was 489.58 kgCO₂e/m², below the RIBA 2030 target of 540 kgCO₂e/m².
Can sustainability improve delivery?
There is also a programme argument for making these decisions earlier. At New Kingsland in Bristol, early engagement helped Stepnell move from load-bearing masonry to a timber-frame structure incorporating BEWI thermal floor systems, air source heat pumps and solar PV.
The project had an initial predicted carbon reduction of 37%, alongside a reported 65% reduction in emissions from space heating and hot water. The change in construction method also reduced the programme by five weeks, bringing the building to weather-tightness five weeks earlier and removing bricklaying from the critical path.
The example shows how construction methods, carbon performance and programme can be considered together. Early involvement alone, however, does not guarantee results.
Jennie argues that sustainability and contractor input need to be introduced at RIBA Stages 1–2, during feasibility, rather than waiting until Stage 4, when key design parameters are already fixed. Carbon assessment must then remain part of project decisions through cost planning, progress meetings and clear responsibilities across the project team.
For clients, the challenge is to consider the cost, carbon and performance of an asset over its entire lifetime from the outset. Once the main design choices have been fixed, the opportunity to improve them narrows, and changing direction can become considerably more expensive.
How consistently whole-life carbon assessment informs these early decisions is also the subject of ongoing research by the Centre for Construction Best Practice (CCBP), with Stepnell among the organisations contributing to its work on whole-life carbon assessment (WLCA).
Early findings from 35 interviews and five focus groups indicate that 70% of respondents, including local authorities, contractors and consultants, said current policy and regulation had no, limited or variable influence on WLCA implementation. The research is ongoing, with CCBP seeking further evidence from across the built environment to understand how assessments are being used in public sector construction and infrastructure, and what could improve their consistency and influence on project decisions.
Public sector clients, contractors, consultants, engineers, project managers and other built-environment professionals can contribute by completing the survey.
