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SPoW Sustainability Checklist

Date published

This Checklist should be used to guide the structural engineering design process towards achieving sustainable outcomes, focusing on low carbon design over which the structural engineer holds significant influence.

The checklist may also aid in developing scope of works, budgeting and planning resources to undertake these tasks. 

Topics and actions are grouped to approximately align with the numbering system of the SPoW Sustainability Report.

1. Initial actions

1a. Inform - Raise awareness and understanding amongst Client and Design team
  • Make yourself familiar with resources at IStructE Sustainability Resource Map.   

  • Facilitate an initial sustainability workshop with the design and client team to discuss sustainability importance and impact within structural design.   

Further reading
1b. Understand - Review requirements of relevant sustainability ambitions, policies and goals
  • Review Client's Sustainability Statements and Net Zero commitments, in conjunction with workshop in 1a.
  • Review requirements of any local policy, regulations and standards requirements and accreditation credits.
  • Review potential future policy changes, or locally relevant advocacy initiatives to identify opportunities for the client to go beyond the minimum requirements.
Further reading

UKGBC - Commercial Playbook
New London Plan 2021

1c. Offsetting and Net Zero - Agree approach to offsetting and/or achieving net zero with client
  • Using estimated carbon footprint for building, investigate and communicate approximate offsetting costs through certified schemes based on IStructE offsetting note.
  • Specifically reiterate that the hierarchy for Net Zero Design involves minimising material use first, specifying low-carbon materials second, and offsetting as a last resort only.
Further reading
IStructE – A Short Guide to Offsetting  
IStructE – The Hierarchy of Net Zero Design
LETI - Net Zero 1-Pager
UK Net Zero Carbon Buildings Standard

2. Actions that inform the brief

2a. Maximise Reuse Opportunities - Consider all opportunities to reduce demand for new materials
  • Advocate for minimal intervention by reviewing buildings in the vicinity, or in the client's wider portfolio, which could be suitable for retrofit/refurbishment, and demonstrate potential value of this approach to the client.
  • Investigate opportunities for component reuse (e.g: foundation reuse, or use of reclaimed steel from other projects or other industries), and reclaiming or recycling on site materials (e.g. masonry or concrete).
  • Discuss actions required to enable this, which may include commissioning a pre-demolition audit, specialist involvement, testing, additional time/cost resource, aesthetic considerations.
Further reading
IStructE - An Introduction to Refurbishment
IStructE - Reuse of Structural Components and Materials
IStructE - A Short Guide to Reusing Foundations
2b. Enable Low Carbon Design - Challenge brief requirements that are restrictive to low carbon design
  • Advocate for brief changes to avoid long spans, shallow structural zones, transfers, basements & redundant structures.
  • Review proposed building massing considering structural efficiency and cross discipline impacts.
  • Review proposed ULS and SLS criteria, including loading allowances, and identify ways in which this could be challenged to reduce material use. (See also 4a-4f below)
  • Support with rough comparative carbon calculations
Further reading

IStructE - Design for Zero
Lean Design - 10 Things to do Now

2c. Materiality - Consider a full material pallet that can be beneficial to the scheme
  • What structural materials are locally available and most suited to the building’s setting, typology and other requirements (e.g. lightweight vs thermal/damping mass, easily transported to site, compatible with off-site manufacture, buildable and maintainable by local workforce)?
  • Does the client have any incentives to support or overcome towards or against any specific materials?
  • Are there insurance or costing issues that could be overcome with early stakeholder engagement? 
Further reading

IStructE - Making Low Carbon Material Choices 
IStructE - Seeing the Bigger Picture

2d. Carbon Targets - Set Embodied / Upfront Carbon targets
  • This should consider project requirements, wider requirements (refer 1b Understand), and use industry benchmarking e.g. SCORS, LETI, RIBA.
Further reading
LETI - Target Alignment
IStructE- Setting Carbon Targets (SCORS)
2e Flexibility vs Adaptability - Agree adaptability strategy with minimal upfront carbon considering likely adaptability needs
  • Consider client profile, building typology, design life & location to understand levels of certainty around future use of building, engage with planners to understand the long term vision for the area.
  • Agree strategy towards designing for adaptation in order to avoid increasing upfront carbon as far as reasonably possible (e.g. through access to structure for strengthening, drop out panels for service distribution, etc). Demonstrate cost benefits of targeted strengthening when strengthening becomes a certain requirement, instead of blanket upfront flexibility/adaptability through excessive loading and serviceability criteria.

Ensure adaptation strategies align across disciplines.

2f. Durability and Circularity - Agree strategy considering the expected life span of the building
  • Discuss expected lifespan with the Client, considering local trends and historical data for similar buildings.
  • For short-life buildings, focus on circularity. Agree an end-of-life strategy with the client that maximises reuse potential (e.g. designing for re-location, disassembly, mechanical connections, repetitive standard components, standard member lengths).
  • For buildings likely to have a long life, focus on durability. Delay end-of-life, prioritising long lasting detailing and solutions that minimise emissions today (e.g. composite construction, in-situ concrete).
  • Prioritise whole building longevity and reuse, component reuse, then material recovery for recycling.
Further reading

IStructE - Applying Circular Principles to the Design Process
IStructE - Enabling Steel’s Circular Economy Potential
GLA Circular Economy Primer
GLA - Circular Economy Statement Guidance
LETI - Circular Economy 1-Pager
New London Plan 2021 - Circular Economy

2g. Resilience to Climate Change - Assess requirements toward changing environmental conditions and ability to recover from extreme events
  • Investigate and understand impacts of changing environmental conditions (e.g. temperature, wind, snow, precipitation, sand, pollution, floods etc) using UK Climate Projects and following BREEAM Wst 05 credit methodology.
  • Consider changing demands to occupant comfort and other needs which the structural design influences the strategy towards.
  • For both, consider how expected future conditions (within the asset’s lifespan) can be incorporated into the design with minimal impact on upfront carbon.
Further reading

IStructE - Resilience-based Design of Structures
IStructE - Lean Yet Resilient
Met Office - Future Climate Projections

2h. Innovation - Discuss opportunities for innovation to challenge traditional methods and associated carbon intensive activities
  • Investigate opportunities to utilise local products, timber and other nature-based materials, proprietary products that benefit from advanced R&D, modern methods of construction, performance based design, technological solutions to control vibration, installation of sensors – consider using small low risk parts of building to trial concepts for innovation.
  • Consider risks to cost, programme, planning, cross-discipline design, construction, use and maintenance implications.
  • Assess required actions, which may include specialist involvement, R&D input, additional time/ cost resources, etc.
Further reading

IStructE - Innovation in Engineering
IStructE - Scaling Low Carbon Construction Materials 
IStructE - Structural Engineering Innovation for a Zero-Carbon World

2i. Wider sustainability - Review sustainability objectives beyond carbon emissions.
  • Identify areas within the United Nations Sustainable Development Goals ( beyond carbon that could be addressed through the project.
  • Identify opportunities to increase overall project sustainability of, e.g. ways in which to improve biodiversity through regenerative design.
Further reading

IStructE - A Targeted Approach to the UN Sustainable Development Goals
IStructE - Addressing the Biodiversity Emergency

3. Actions related to carbon calculations

3a. Carbon Calculations - Calculate carbon and present results at key project stages and to inform design decisions
  • Don’t let uncertainty deter you from undertaking carbon calculations – do them anyway, whilst remaining aware of and clearly communicating the scope and limitations of your assessment.
  • Use estimations and like-for-like studies at early stages and undertake increasing detailed calculations through design stages.
  • Report scope, assumptions and limitations of the assessment.
  • Provide a summary against the targets.
  • Track carbon through the design process.
  • Identify opportunities for reduction at every stage.
  • Communicate opportunities and progress to the design and client teams regularly (i.e. add to agenda for team and client meetings).
  • Share results to internal and industry databases such as the Built Environment Carbon Database.
Further reading

IStructE How to Calculate Embodied Carbon Guide
IStructE Carbon Calculator Tool 
IStructE - Seeing the Bigger Picture

4. Actions to minimise emissions through design (This section builds upon the item 2b)

4a. Configuration - Advocate for decisions that result in efficient structural forms, to reduce carbon footprint
  • Challenge long spans, shallow structural zones, transfers, basements & other requirements which increase carbon, highlighting the carbon impacts of each.
  • Propose the lowest carbon approach as your default design, assess options against this baseline to highlight the carbon cost of decisions.
  • Review floor to floor heights to ensure efficient structural solution (considering services distribution, which may be combined within depth), including an estimate of the impact of increased heights on carbon in vertical elements (e.g. facades, partitions).
  • Advocate for sensible location of heavy (or dynamically sensitive) equipment, and usage of roof for plant and PVs.
  • Consider standardisation opportunities to unlock modern methods of construction benefits, reviewing carbon impacts of these decisions.
  • Ensure efficient layouts of cores and vertical systems, reducing services distributions and the need for transfers and complex framing
Further reading

IStructE - What do we mean by efficiency? 
IStructE - Design for Zero

4b. Structural solutions - Undertake optioneering studies to present carbon comparisons of schemes
  • Review different superstructure, substructure and facade systems, estimating the carbon footprint of each, and advocating for the lowest carbon combined solution.
  • Consider carbon impacts of using different materials and different systems, remembering to account for the full build-up of walls and floors.
  • Review options for use of ground bearing solutions for lowest level slab and façade support.
  • Consider alternative and low-carbon foundation solutions.
  • Consider ways to incorporate local and novel products and solutions.
Further reading

Lean Design - 10 Things to do Now

4c. Strength (Loading requirements) - Ensure loading aligns with requirements and codes are used to remove conservatism
  • Permanent & partition loads should be accurately assessed based on systems specified. Encourage lightweight systems and finishes.
  • Use codified reduction factors within load combinations (e.g. multi-storey building factors, EC0 eq.6.10a and b at detailed design, etc).
  • Weather loads (refer 2f Resilience) should be accurately derived with codified coefficients - detailed modelling and specialist involvement may enable further reductions. Consider wind tunnel testing where possible.
  • Safety - Undertake detailed fire calculations, avoid conservative code tables.
  • Accidental actions should be accounted for through a risk based approach with specialist involvement where necessary.
  • Explore the possibility of using reduced live loading, in areas such as storage - Note any deviation from design standards may require client approval, further justification and additional liability.
  • Coordinate with Architect: Position heavy equipment on ground bearing slabs, suspended slabs with short spans and greater structural depth or isolate heavy loads close to vertical supports.
Further reading

IStructE - A weight off your mind
IStructE – Structural safety when designing lean
IStructE - Structural fire safety when responding to the climate emergency

4d. Serviceability - Review serviceability limit state criteria, avoid conservative approaches and align with requirements of specified systems
  • Accurately define deflection, sway, cracking, settlement and dynamic criteria based on systems and usage (e.g. ensure façade criteria is aligned with supplier requirements).
  • Relax criteria or allow local exceedance where possible to do so.
  • Crack requirements should not govern unless water retaining or exposed surfaces reduce requirements for finishes.
  • Accurately assess vibration if governing, consider actual walking patterns and critical response areas, consider adapting layout to reduce excitation and isolate sensitive equipment/spaces.
  • Use pre-cambering and pre-setting where deflection governs.
Further reading


4e. Optimisation - Include sufficient time and fee to optimise design, demonstrate value in terms of carbon and cost savings
  • Seek early design freezes with the client and design team, particularly prior to Tender, to enable time to carry out final member calculations and reduce sizes where feasible.
  • Ensure ULS governs where possible with high utilisations both in ULS and SLS (note this must be accompanied with efficient sizing and form).
  • Remove uncertainty as early as possible, ask the Client to undertake early Ground Investigations to understand ground conditions.
  • Material strengths optimised for design requirements e.g. use lowest strength concrete required for durability and crushing in beams and slabs, use higher strength concrete in compressive members, use S460 steel for columns and other compressive members governed by strength not stiffness.
  • Account for full restraint conditions of members governed by buckling. Increase connection fixity if beneficial and practicable to do so.
Further reading

IStructE - Rationalisation v Optimisation  

4f. Supporting other disciplines - Summarise the approaches taken to reduce carbon in elements designed and specified by other disciplines
  • Consider reduced services distribution, balancing of structural zones with vertical service / circulation / façade systems, provision of thermal mass.
  • Work with the wider design team to compare upfront and operational carbon of facade system options and discuss the interdependencies of the structural design with the façade design and MEP design.
  • Advocate for the façade engineers and services engineers to conduct sensitivity analyses on the balance of embodied and operational carbon over the whole life of the building.
  • Coordinate with all disciplines to reduce finish requirements (fire, durability, noise, aesthetics), particularly raised access floors and screeds which can be very carbon intensive.
Further reading

IStructE - Balancing embodied and operational carbon in building envelope design

5. Actions to reduce emissions throughout construction

5a. Specification - Include key sustainability requirements in material specifications
  • Align specification to embodied carbon assessment assumptions. Refer to industry guidance on specifying low-carbon concrete and steel. Avoid over-specification, leave flexibility for concrete mix designers to achieve low carbon solutions.
  • Discuss specifications with contractors to understand limitations and possibilities. Safeguard sustainability measures against value engineering or programme pressures i.e. enforce maximum cement content so concrete strength isn’t increased for time gains.
  • Identifying elements which may be more suitable for reused steel (e.g. secondary steel).
  • Always request certified Environmental Product Declarations from suppliers.
  • Further reading
National Structural Steelwork Specification - Appendix J - Sustainability
Concrete Centre - Specifying Sustainable Concrete
5b. Procurement - Ensure carbon is considered through procurement. Develop approach to leverage supply chain involvement towards emission reductions
  • Advocate for early contractor engagement and facilitate contractor workshops to discuss approaches taken to reduce carbon and opportunities for the Construction Stage.
  • Establish mechanism for undertaking as-built assessment of upfront carbon impacts as well as logging of EPDs.
  • Establish requirements in the tendering process to provide carbon saving solutions, weighted to encourage strong proposals. Stipulate supply chain to be members of relevant industry bodies that encourage energy and carbon efficiency from their members e.g. The MPA, Responsible Steel, Steel Zero etc.
  • Share data and design decisions (including the Sustainability Report) to allow the Contractor to understand design intention and optimise CDP items (e.g. steel connections, RC detailing, foundations).
  • Transfer responsibility for specialist systems (e.g. modular, composite, precast) to suppliers to increase efficiencies.
  • Engage with contractors on temporary requirements and construction methodology to limit increase in material usage beyond that required for the permanent condition.
  • Ensure requirements for net zero commitments and contribution to industry decarbonisation of materials in the supply chain are appointed.
  • Include industry best practice responsible sourcing requirements. Ask Contractors to provide evidence that local sourcing was considered during procurement.
5c. Enabling In-Use and End of Life Benefits - Ensure construction detailing and methods satisfy in-use and end of life design intent
  • Ensure detailing and procurement match intent; where reuse is prioritised this may involve specifying element lengths, connection locations and types, limiting in-situ works and welding.
  • BIM model should be used to store as-built information (including carbon data), acting as a digital twin to be used during and at end of life.
  • Ensure plan for responsibly disposing biogenic materials to avoid end of life emissions i.e. timber to be incinerated, ideally with energy recovery, and not going to landfill.
  • Detail for easy waste stream separation and recycling where reuse is not achieved.

6. Actions to reduce carbon emissions on future projects

6a. Lessons Leant - Capture feedback. Report success and failures to inform future work
  • What was effective and what hurdles were present?
  • What sustainability deliverables were achieved and missed?
  • Share findings internally and externally where suitable to do so.
  • Improve approach, language and influence.
  • Conduct required research or studies identified.
  • Develop R&D and innovation plans required to address barriers.
  • Investigate opportunities for further collaboration with contractors to develop low carbon construction solutions on future projects.
  • Write case study and offer thought leadership to the Institution to share lessons more widely (e.g. through The Structural Engineer and conferences).