THE VALUE OF STRUCTURAL ENGINEERING TO SUSTAINABLE CONSTRUCTION Sarah Kaethner: Arup

Context

UK Built Environment CO2 Timeline 2050

Construction Materials are Important Global C02 Industry Process optimised for energy = Technology will not solve problem Construction optimised for cost and time = Market will not solve problem Lowest cost, fastest construction = More material, less labour

Structural Engineering Changes Lives

Why we did this research Structural Engineer’s work is important Structural Engineers say that clients are not valuing the contribution of Structures Green Building Rating Schemes are valued by clients

Scope & Method

Global Project: Many Schemes

Structural Team Member Construction Management Acoustics Lighting Health & Comfort Energy

What do they measure?

Evidence based process Contribution of structure to the schemes Study of rating schemes from around the world Study actual project scores How much should structure be worth? Literature review & Arup CO2 profiles Detailed review of credits by topic Collection of experience through survey literature review Recommendations For scheme For credits

Framework An effective credit would: Provide incentives for sustainable actions; Provide a measure of the sustainability of the structure to enable comparison between buildings; Provide a framework to define sustainable design practices for professionals; Work as a practical tool which can be deployed cost-effectively during the procurement of buildings.

Findings

Schemes were not an effective incentive “In most cases the (BREEAM) Mat1 system is opaque, complicated, counter-intuitive and not linked to significant sustainability improvements..”

Materials don’t contribute to high scoring projects

Consistency of Credit Topics Reuse Recycled Content Responsible Sourcing Local Sourcing LCA Durability Efficiency Adaptation High Performance Cement Replacement

Individual Topic Assessment Recycled aggregate example

Example: Recycled Aggregate

Example: Recycled Aggregate % of respondents agreeing BREEAM >40 20-40 Strengths Encourages the development of good practice Does not impact on other aspects of the design It rewards sustainable actions The measure is simple and clear Barriers Resistance from design and procurement team Does not respond well to my regional context Technically difficult Effort to achieve is not proportional to reward Too expensive Measuring the wrong thing/in the wrong way

Example: Recycled Aggregate “It is almost impossible to commercially achieve credit... unless you have lots of hard landscaping to do the % is too high for concrete and misses the opportunities in cement replacement measures which arguably have a much higher impact on sustainability” “There is some benefit to reduction in waste but aggregates are plentiful in the UK so the impact on resource depletion is... insignificant.”

Findings Low Scores Common topics The credit detail is important Schemes need to support changes in industry not just measure building.

Recommendations …..Recycled Content Super-structure should be excluded from credits which reward whole building recycled content. If an individual recycled content for structural concrete is included this should include a pre-requisite to reduce Portland cement content, and practical achievable levels of including a known locally available secondary material in the concrete. ……….

What has happened since?

Life Cycle Assessment more prominent Additional credits in BREEAM and LEED Environmental Product Declarations are promoted Are requirements clear? Are the tools accessible?

Routemap – Carbon Reporting Now Develop measurement rules for construction products Establish databases of performance Encourage measurement and reporting 2017-2020 Mandatory Environmental Product Declarations (EPDs) for all construction products Mandatory measuring and reporting of whole life carbon for public buildings through Government procurement 2020+ Set whole life carbon targets in Building Regulations

Key issue is Benchmarking NOT IN BREEAM!

Responsible Sourcing Developing

Drivers for sustainable design decisions Materials efficiency/flexibility/durability credits in BREEAM Little guidance on how to implement in practice

Structural Engineer more engaged? LEED: “One of the things we want to try to do is to initiate a discussion between the designer and the structural engineer in the same way that that energy modelling initiated a discussion between the designer and the mechanical engineer” (Scot Horst: Chief Product Officer U.S. Green Building Council : 2013)

Next Steps

Industry BIM for efficiency Life Cycle Assessment, benchmarks and EPDs Responsible Sourcing End of Life supply chain

Next Steps Review and guidance for the new credits. Influence Schemes & Government on important topics e.g. substructure, Building Regulations

Structural Engineers Use WRAP database Push for EPDs and CO2 tools Work collaboratively to balance material efficiency, cost and buildability. Specify to support the material supply chain

Structural Team Member