Global construction consultants Global construction consultants

Whole life carbon accounting for the Treasury Green Book

John ConnaughtonDavis 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 CO2

Whole life Carbon Footprint

In-use CO2Embodied CO2

Regulation (Part L) is reducing the relative significance of in-use emissionsMajor construction materials/components are relatively energy intensive, andMany low energy/carbon strategies are resource intensive (eg increased mass; tehcnology strategies)

Why embodied?

Rule of thumb: 75:25 operational to embodied ratio for buildingsBUT 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 STRUCTURES100% 75% 50% 25% 0%

100%75%50%25%0%

SPORTS BUILDINGS, STADIA

Towards Zero CO2 Operational Impacts

Calculating Embodied Carbon

Holorib

Lightweight Concrete

Mesh Reinforcement

Shear Studs

Mass /m2

Mass /m3

Mass /m2

Mass/nr

Carbon/kg

Carbon/kg

Carbon/kg

Carbon/kg

Composite Upper Floor

Carbon /m2

Calculating Embodied Carbon

Sand and

AggregateCarbon/

kg

Cement Mass /m2

Mass /m2

Carbon/kg

Lightweight

ConcreteCarbon /

m2

OPC

GBBS

PFA

WaterMass /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 m3 of 1.5:2:3 concrete mix?

Construction metrics

How much by mass (kg) of 1.5:2:3 concrete is there in 1 m2 composite floor slab?

Embodied CO2 benchmarking with Davis Langdon’s Carbon Calculator

1

4 4

1

0

1

0

3

4

7

6

7

10

Sample of 48 office projects assessed by Davis Langdon

Embodied KgCO2 per m2 GIA

0-25

0

250-

500

500-

600

600-

700

700-

800

800-

900

900-

1000

1000

-125

0

1250

-150

0

1500

-200

0

1500

-200

0

2000

-250

0

2500

-300

0

Offices CO2 emissions study

423357

229359 366 392

455354 385

81160 191

189

146 123 85

147

138142

77

77

218

258162 197 181

191

215220

161

46

106150

92 70 140

60125

120

19

Structural elements Building fabric Internal walls and finishes M&E

Embodied CO2 of 10 different office projects from the same developer

Embodied kgCO2 per m2 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 CO2 in existing office stock

Commute Operational Embodied

The increasing significance of embodied carbon

Whole life CO2 emissions annualized for 30 years with adjustments

London W

Present Near 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 impactsAssesses costs and benefits at market rates

Some important issues for whole life carbon:

Green Book excludes sunk costsIncludes residual value (at end of life?)Assessign GHG emissions – reference to DEFRA work on social cost of carbon

CEN/TC 350

Whole life carbon methodologyA life cycle assessment approach

Product ‘information module’

Building life cycle

Recycling for other ‘systems’

CEN/TC 350

Whole life carbon methodologyA life cycle assessment approach

RecyclabilityRecycled 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 stagesProduct Embodied

Construction Including ‘start of life’ demolition, enabling work

In use Including repair, maintenance and replacement

End of life Including ‘end of life’ demolition; recyclability?

This could help:Set and understand benchmarks

Improve the regulatory focus

Global construction consultants Global construction consultants

Whole life carbon accounting for the Treasury Green Book

John Connaughton john.connaughton@davislangdon.com Davis Langdon