Dr. Sarah Ward

Associate Research FellowCentre for Water Systems

University of Exeter

Rainwater harvesting for the 21st Century: Challenges &

Opportunities

The Future of Rainwater Harvesting in BuildingsSCI, Belgrave Square, 23rd February 2011

OverviewChallenges• Conflicting Messages

• Unclear Guidance • Energy Consumption in Context

• Uncertainty on scale and skillOpportunities• Assessing Receptivity/Acceptability

• Perceptions of Health and Safety• Evidence for Water Saving Efficiency

The Way Forward?

Challenge

CfSH – RWH needed for L5/6 (80l/p/d)

(DCLG, 2006)

Latter only assesses Average Incremental Carbon Cost:

• Does not include wider environmental or socio-economic cost-benefits e.g. shadow price of water, stormwater attenuation (new research available), resilience, adaptability

• Uses ‘future scenarios’, but does not assess emerging retrofit gravity systems i.e. ‘future systems’

• Carefully consider ALL aspects before it’s ruled out!

Conflicting Messages:

RWH increases CO2 footprint of buildings(EA/NHBC, 2010)

Vs

ChallengeUnclear guidance on water-energy trade-offs:

• RWH is not the only water-saving technology that can increase energy/carbon consumption

Do we stop installing low water-high energy appliances?

ChallengeEnergy Consumption in Context:

E = energy consumed CO2 = carbon dioxide emitted

Cost = cost of energy used SM = Simple Method

IM = Improved Method M = Measured Mains = mains water equivalent

LCA = full embedded & operational impact

* = Australian Study (domestic systems; Gardner et al., 2008)

Innovation Centre RWH System,

University of Exeter:

< 0.1% of total building energy

consumption

ChallengeUncertainty on scale and skill: In the UK SMEs represent 99.1% of all enterprises, 59.4% of private sector

employment and 50.1% of turnover – a lot of buildings/water use!

Interviews with SMEs: Non-implementers/Implementers; Retrofit/New Build

Five Implementation Deficit Categories

1) Expertise and Advice 2) Guidance and Support3) Visibility and Access 4) Confidence and Communication

5) Finance and Consultation“Needed to know so much about all this technical stuff, which was all too much, both time and stress-wise.” (Retrofit)

“...feeling like the guinea pig…” (both)

“The system is not well organised enough to support everything and you’re left to sort it out.” (New Build)

Why aren’t more SMEs engagingwith SWM/RWH?

• Primary reason: complexity of process – information gathering, support and implementation

Opportunity

Assessing Awareness:

Receptivity

‘…don’t see it advertised; get solar panel things

through the door, but not for water’.

Broadclose (Bude) & Innovation Centre

OpportunityAssessing Awareness:Acceptability• Having to pay for regular maintenance • Having disruption to my home/life during installation• Willingness to pay was less than estimated cost

Broadclose & Innovation Centre

OpportunityPerceptions of Health and Safety:

Innovation Centre System

Microbiological Quality

Building Design Features

OpportunityPerceptions of Health and Safety:

• Aside from misconnections, health risk is minimal

OpportunityEvidence of Water Saving Efficiency:

• Greater visibility of REAL data for REAL systems at DIFFERENT SCALES

Innovation Centre System

(i) ~£1500/year saving

(ii) Capital PBP = 11 years (tank installed is oversized)

21st Century RWH: The Way Forward?

Increase efficacy of RWH for UK stakeholders e.g. enhance technical

relevance by developing new products

Reliable, central, independent

source of information

required

Increase stakeholder

consultation and engagement

activities

A Clear Vision

• Innovation

• Research

• Partnerships

Conclusions• Move beyond focus on current system configurations

• Consider financial, technical and social perspectives

• Use opportunities to innovate systems and implementation models to overcome trade-offs, challenges and obstacles

• Find a ‘vision’ for RWH in the UK fit for the 21st century – provide a direction for ‘re-designing RWH’

Sarah Ward

sw278@exeter.ac.uk

Rainwater Harvesting for the 21st Century: Challenges and Opportunities

QUESTIONS?

The Future of Rainwater Harvesting in BuildingsSCI, Belgrave Square, 23rd February 2011