Global construction consultants Whole life carbon accounting for the Treasury Green Book John Connaughton Davis Langdon

Whole life Carbon Accounting: Key points The concept of whole life carbon The importance of ‘embodied’ carbon What whole life carbon assessment looks like Key challenges and emerging thinking Green Book and carbon accounting issues

Whole life CO 2 Whole life Carbon Footprint In-use CO 2 Embodied CO 2 Regulation (Part L) is reducing the relative significance of in-use emissions Major construction materials/components are relatively energy intensive, and Many low energy/carbon strategies are resource intensive (eg increased mass; tehcnology strategies)

Why embodied? Rule of thumb: 75:25 operational to embodied ratio for buildings BUT IS THIS CORRECT? Surely the proportion will vary depending on building type? 100% 75% 50%25% 0% 100%75%50%25%0% OPERATIONAL IMPACTS EMBODIED IMPACTS INFRASTRUCTURE HIGHLY SERVICED BUILDINGS HOUSING OFFICES SPORTS BUILDINGS, STADIA BASIC STRUCTURES

Why embodied? What is the impact of the trend towards ‘zero carbon’ buildings? OPERATIONAL IMPACTS EMBODIED IMPACTS INFRASTRUCTURE HIGHLY SERVICED BUILDINGS HOUSING OFFICES BASIC STRUCTURES 100% 75% 50%25% 0% 100%75%50%25%0% SPORTS BUILDINGS, STADIA Towards Zero CO 2 Operational Impacts

Calculating Embodied Carbon Holorib Lightweight Concrete Mesh Reinforcement Shear Studs Mass /m2 Mass /m3 Mass /m2 Mass /nr Carbon/ kg Composite Upper Floor Carbon /m2

Calculating Embodied Carbon Sand and Aggregate Carbon/ kg Cement Mass /m2 Carbon/ kg Lightweight Concrete Carbon /m2 OPC GBBS PFA Water Mass /m2 Carbon/ kg

Some challenges Basic construction materials How much carbon is used in the production of, say, 1 tonne of cement? Composites How much cement (kgs) is there in 1 m 3 of 1.5:2:3 concrete mix? Construction metrics How much by mass (kg) of 1.5:2:3 concrete is there in 1 m 2 composite floor slab?

Embodied CO 2 benchmarking with Davis Langdon’s Carbon Calculator Sample of 48 office projects assessed by Davis Langdon Embodied KgCO2 per m2 GIA

Offices CO 2 emissions study Embodied CO 2 of 10 different office projects from the same developer Embodied kgCO 2 per m 2 GIA

Whole life carbon impact : the bigger picture Construction Commuting Operational Total impact Embodied in construction materials and components Emitted in travelling to and from the building Emitted from the use of energy by the building occupants and processes Recent study by a major offices developer to assess CO 2 in existing office stock

The increasing significance of embodied carbon Whole life CO 2 emissions annualized for 30 years with adjustments London W PresentNear FuturePast 11% 71% 17% 11% 71% 17% 15% 62% 23% 20% 52% 28%

The Green Book Best practice techniques for project and policy assessment Describes how economic, financial, social and environmental assessments should be combined Where possible, attributes monetary values to impacts Assesses costs and benefits at market rates Some important issues for whole life carbon: Green Book excludes sunk costs Includes residual value (at end of life?) Assessign GHG emissions – reference to DEFRA work on social cost of carbon

CEN/TC 350 Whole life carbon methodology A life cycle assessment approach Product ‘information module’ Building life cycle Recycling for other ‘systems’

CEN/TC 350 Whole life carbon methodology A life cycle assessment approach Recyclability Recycled content

Current measurement issues and challenges Will CEN/TC 350 resolve them? Consistent product data – what are things actually made of? Consistent carbon data – what is the impact? Manufacturing processes, energy sources, location/transport, etc Bio-renewable (organic) materials Boundary conditions – including accounting for recycled content and recyclability?

Some thoughts on whole life carbon accounting Shortcomings in ‘global’ indicators for buildings – eg kgs of whole life CO2 per square metre floor area Take a lead from CEN/TC 350 and express impacts over key stages ProductEmbodied ConstructionIncluding ‘start of life’ demolition, enabling work In useIncluding repair, maintenance and replacement End of lifeIncluding ‘end of life’ demolition; recyclability? This could help: Set and understand benchmarks Improve the regulatory focus

Global construction consultants Whole life carbon accounting for the Treasury Green Book John Connaughton Davis