A Systematic, Multi-Criteria Decision Support Framework

for Sustainable Drainage Design

Jo-fai Chow, Dragan Savić,David Fortune,Zoran Kapelan,Netsanet Mebrate

You can download this presentation from

http://tinyurl.com/chow-ccwi2013

photo's courtesy of www.pptbackgrounds.net

About this Presentation

• Background•Green Values of Drainage Systems• Evaluation Framework•Maximising Multiple Benefits• Conclusions

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Background

• Trends in Drainage Industry• Moving towards a sustainable

approach

• Challenge• Lack of commonly agreed

standard for sustainable drainage design

• Objective• To develop a new decision

support system for sustainable drainage design

• Collaboration• EPSRC, STREAM IDC,

University of Exeter and XP Solutions

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Sustainable & BalancedApproach

Traditional & BiasedApproach

Water Quantity Water Quality

Other Benefits

Water Quantity

Water Quality

Why Sustainable Drainage Design? Green Values of Drainage Systems

• Water Quantity• Runoff reduction, flood risk mgt., re-

use

• Water Quality• On-site treatment

• Environmental Impact• Cleaner water & air, amenity,

biodiversity, recreation, community

• Energy Saving• Less cooling/heating, reduced carbon

footprint

• Green Image of Business

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photo's courtesy of XP Solutions photo's courtesy of ReneCreate

photo's courtesy of EMPowerHouse

photo's courtesy of

roanokeoutside.com

photo's courtesy of nzconservation.wordpress.c

om

photo's courtesy of Arup photo's courtesy of Polypipe

photo's courtesy of gregwalcher.wordpress.co

m

photo's courtesy of china.org.cn

photo's courtesy of Deloitte

Quantifying Green Values:From Good Feelings to Real Numbers

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Calculations based onprevious research projectsand case studies.

For more information:

1.Conference Paper2.This presentation online

(tinyurl.com/greenvalues)

Using physical attributes & location of infrastructures to calculate costs.Four main categories of performance measures.Key performance indicators (KPIs) calculated for each infrastructure.Calculate monetary measures of benefits based on KPIs.Consider costs and benefits over the design life of systems.

Putting the Numbers Together: A Systematic Evaluation Framework

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Information from a typical drainage model.

Using the Framework – Inputs:Components in a Drainage Design Model

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BioretentionBioretention

PermeablePaving

Wetland

Swale

Swale

photo's courtesy of XP Solutions

Using the Framework – Outputs:Operational and Capital Expenditure

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Swales are relatively cheap to build and maintain.

Question: can the costs be justified?

Permeable paving costs a lot more to build and maintain.

Using the Framework – Outputs:Key Performance Measures

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Permeable paving can effectively reduce runoff via infiltration

… but it does not add amenity value to the community.

At a fraction of the cost, swales can provide moderate runoff reduction

and increase the amenity value as a result of the green surface areas.

Goal: moving away from subjective opinions to evidence-based comparison.

Comparing Different Approaches: Green (Sustainable) vs. Grey (Traditional)

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BioretentionPermeablePaving

BioretentionWetland

Swale

Swalephoto's courtesy of allbiz

Storage Tank

Question: is it worth considering the green approach after all?What do you think?

Let’s consider the sustainable design example discussed in previous slides again.

What if we replace the swales and wetland with storage tanks?

Comparing Different Approaches: Green (Sustainable) vs. Grey (Traditional)

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Green approach can provide multiple benefits in addition to water management.

Green approach costs about the same to operate, much less to build yet a lot more for the land occupied when compared to grey approach.

In this case, the framework suggests similar long-term costs for both approaches.

(Let me repeat the key message again…)Goal: moving away from subjective opinions to evidence-based comparison.

Comparing Multiple Drainage Design Options

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Different design options.

Comparing multiple benefits with parallel coordinates.

Comparing cost-benefits for different options.

Next Step: Beyond Evaluation - Maximising Multiple Benefits

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•Design Consideration:• Legislative Requirements• Location• Sizing• Type & Order

• Identifying Trade-offs:• Multiple benefits• Multi-objective

optimisation

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photo's courtesy of University of Sheffield

photo's courtesy of XP Solutions

photo's courtesy of BME Imaging

photo's courtesy of bfrss.org.uk

Conclusions 14 of 15slides

• Challenges: lack of commonly agreed standard for sustainable drainage design.

• Aim: to develop a new decision support system.

• Why green infrastructures? Because they can offer multiple benefits in addition to water management.

• Quantifying green values with KPIs and monetary measures.

• A systematic evaluation framework - evidence-based comparison, a better tool for optioneering.

• Integration with multi-objective optimisation – encourage the consideration of multiple benefits.

• Research outputs for industrial sponsor: new features in their drainage design software suite.

• “Essentially, all models are wrong, but some are useful.” – Professor George E.P. Box

photo's courtesy of Amazon

Thank you for your attention

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Any questions?Many thanks to Prof. Dragan Savić who kindly agreed to present this for me!

jo-fai.chow@stream-idc.nethttp://tinyurl.com/chow-ccwi2013

http://tinyurl.com/greenvalueshttp://tinyurl.com/xpdrainage

Additional Information:Capital and Operational Expenditure

Extraslides

Additional Information:Estimation of Annual Reduced Runoff (m3)

Extraslides

Additional Information:Annual Energy Savings

Extraslides

Additional Information:Amenity Value of New Habitats

Extraslides