21 st -23 rd February 2007 NZSSES Conference, Auckland 2007 1 Sustainable choices for residential water supply in Auckland Sustainable choices for residential

21st-23rd February 2007 NZSSES Conference, Auckland 2007 1

Sustainable choices for Sustainable choices for residential water supply in residential water supply in

AucklandAuckland

Nalanie Mithraratne & Robert Vale

Centre for Urban Ecosystem SustainabilityCentre for Urban Ecosystem Sustainability

Landcare ResearchLandcare Research


OutlineOutline

Mains supply vs. rain tanksMains supply vs. rain tanks

Impact of settlement patternsImpact of settlement patterns

Water system in average houseWater system in average house

ConclusionsConclusions


LCA of mains supply LCA of mains supply

System boundarySystem boundary

Initial constructionInitial construction

Maintenance/ replacements - 1% of the Maintenance/ replacements - 1% of the total length of pipes/year total length of pipes/year

replacedreplaced

Operational requirementsOperational requirements

Analysis period – 100 yearsAnalysis period – 100 years


Bulk supply system - constructionBulk supply system - constructionLIFE CYCLE ENERGYLIFE CYCLE ENERGY

Dams 46%

Raw water mains7%

Valve towers, spillways, etc.

2%

Treated water mains45%


Bulk supply systemBulk supply system

Construction

50%

Operation

27%

Maintenance

23%

Maintenance

12%Operation

65%

Construction

23%

LCELCE

LCCOLCCO22


Local supply network - 2005Local supply network - 2005

Unknown 37%

AC19%

CI21%

PE9%

other4%

PVC9%

Steel0% CLS

1%

CLS - cement lined steelCLS - cement lined steel

CI - cast ironCI - cast iron

PE - polyethylenePE - polyethylene

AC - asbestos cementAC - asbestos cement


Mains supply performanceMains supply performance

Energy intensity = 2.11MJ/mEnergy intensity = 2.11MJ/m33 (Range 2.08 - 2.27MJ/m(Range 2.08 - 2.27MJ/m33))

COCO22 emissions factor = 0.128kgCO emissions factor = 0.128kgCO22/m/m33 (Range 0.126 – (Range 0.126 –

0.146kgCO0.146kgCO22/m/m33))

Mains water supply contribution,Mains water supply contribution,

Life cycle energy = 86GJ/houseLife cycle energy = 86GJ/house

COCO22 emissions = 4.9 tonnes CO emissions = 4.9 tonnes CO22/house/house


Impact of Settlement Pattern Impact of Settlement Pattern

Roberton siteRoberton site

Residential density 14units/haResidential density 14units/ha

Parallelogram bounded by roadsParallelogram bounded by roads



Sandringham siteSandringham site


Road across the siteRoad across the site



Freeman’s Bay siteFreeman’s Bay site


Trapezoid, open spaces withinTrapezoid, open spaces within



Ponsonby sitePonsonby site


Rectangle bounded by roadsRectangle bounded by roads


Life Cycle Energy and LCCOLife Cycle Energy and LCCO22 (actual) (actual)

Name of siteName of siteEnergy intensity Energy intensity

(GJ/unit)(GJ/unit)COCO22 emissions emissions

factor (kg/unit)factor (kg/unit)AverageAverage RangeRange AverageAverage RangeRange

RobertonRoberton 10.310.3 4.8 - 15.84.8 - 15.8 3.43.4 0.6 - 6.30.6 - 6.3

SandringhamSandringham 4.94.9 4.94.9 0.30.3 0.30.3

Freeman’s BayFreeman’s Bay 6.86.8 6.6 - 6.96.6 - 6.9 0.40.4 0.3 - 0.40.3 - 0.4

PonsonbyPonsonby 13.513.5 4.9 - 2.24.9 - 2.2 2.12.1 1.2 - 2.91.2 - 2.9


Life Cycle Energy compositionLife Cycle Energy composition

Name of siteName of site ConstructionConstruction MaintenanceMaintenance OperationOperation

RobertonRoberton 25%25% 25%25% 50%50%

SandringhamSandringham 13%13% 13%13% 74%74%

Freeman’s BayFreeman’s Bay 23%23% 23%23% 54%54%

PonsonbyPonsonby 27%27% 27%27% 46%46%


Life Cycle COLife Cycle CO22 composition composition

Name of siteName of site ConstructionConstruction MaintenanceMaintenance OperationOperation

RobertonRoberton 26%26% 26%26% 48%48%

SandringhamSandringham 25%25% 25%25% 50%50%

Freeman’s BayFreeman’s Bay 23%23% 23%23% 54%54%

PonsonbyPonsonby 27%27% 27%27% 46%46%


Mains supply vs. Rain tanksMains supply vs. Rain tanks

Wastewater and stormwaterWastewater and stormwater

Mains - more, rain tanks - reducedMains - more, rain tanks - reduced

Water quality Water quality

Mains - Grade A, rain tanks – untreatedMains - Grade A, rain tanks – untreated

Water supply volume Water supply volume

Mains - 370mMains - 370m33, rain tanks - varies, rain tanks - varies


House size and rain water volumeHouse size and rain water volume

% of the total

Ave. floor area (m2)

Water volume (m3/house)

BIAC - 94 105

1970s 19% 146 163

1980s 13% 149 166

1990s 13% 173 193

Post 2000 10% 194 217


[Source: Marley 2005]]

Rain harvesting systemRain harvesting system


Water supply systems - LCEWater supply systems - LCELIFE CYCLE ENERGY (GJ)LIFE CYCLE ENERGY (GJ)

0

10

20

30

40

50

0 25 50 75 100

USEFUL LIFE (YEARS)

LIF

E C

YC

LE

EN

ER

GY

(G

J)

BIAC - reticulated 1970s - reticulated 1990 - reticulated 2000 - reticulated

BIAC - rain tank 1970 - rain tank 1990 - rain tank 2000 - rain tank


Water supply systems – LCCOWater supply systems – LCCO22LIFE CYCLE CO2 (kg)LIFE CYCLE CO2 (kg)

0

500

1000

1500

2000

2500

3000

3500

4000

0 25 50 75 100

USEFUL LIFE (YEARS)

LIF

E C

YC

LE

CO

2 (k

g)

BIAC - reticulated 1970s - reticulated 1990s - reticulated 2000 - reticulated

BIAC - rain tank 1970 rain tank 1990 rain tank 2000 rain tank


Water supply systems – LCCWater supply systems – LCCLIFE CYCLE COST (NZ$)LIFE CYCLE COST (NZ$)

2500

3000

3500

4000

4500

5000

5500

6000

6500

7000

7500

8000

8500

0 25 50 75 100

USEFUL LIFE (YEARS)

LIF

E C

YC

LE

CO

ST

(N

Z$

)

BIAC - reticulated 1970s - reticulated 1990s - reticulated 2000 - reticulated

BIAC - rain tank 1970s - rain tank 1990s rain tank 2000 - rain tank


Building Industry Advisory Building Industry Advisory Council House (BIAC)Council House (BIAC)

PlanPlan[Source: Baird and Chan (1983)]


Section & Front ElevationSection & Front Elevation[Source: Baird and Chan (1983)]

Building Industry Advisory Building Industry Advisory Council House (BIAC)Council House (BIAC)


ASSUMPTIONSASSUMPTIONS

Useful life of NZ houses is 100 years.Useful life of NZ houses is 100 years. Living room faces north.Living room faces north. Space heating: Whole house, temp Space heating: Whole house, temp

1818ooC, 2 schedulesC, 2 schedules Water heating: varies with water Water heating: varies with water

volume.volume.


Life cycle energy by end useLife cycle energy by end use

BIAC 1970s 1990sPost 2000

House construction

15-17% 14-15% 16-17% 16-17%

Space heating

39-44% 43-47% 44-47% 44-48%

Water heating

40-43% 37-40% 36-38% 35-37%

Water supply 1% 1% 1% 1%


Life cycle COLife cycle CO22 by end use by end use


House construction

57-61% 56-60% 39-43% 39-43%

Space heating

18-21% 20-23% 29-33% 29-34%

Water heating

19-20% 18-19% 24-26% 24-26%

Water supply 0.2 -3% 0.3 -4% 0.4 -5% 0.4 -5%


Life cycle cost by end useLife cycle cost by end use


House construction

81-84% 82-84% 82-85% 82-85%

Space heating

5-6% 6-7% 6-7% 6-7%

Water heating

6% 5% 5% 5%

Water supply 5-7% 4-6% 4-6% 4-5%


ConclusionsConclusions Consumption significantly impacts the Consumption significantly impacts the

system choice.system choice.

Use of mains supply in smaller houses Use of mains supply in smaller houses (>150m2) and rain harvesting in larger (>150m2) and rain harvesting in larger houses is better for the environment.houses is better for the environment.

Mains supply is cheaper initially but Mains supply is cheaper initially but costly in life cycle terms.costly in life cycle terms.

Water supply is negligible in terms of Water supply is negligible in terms of total environmental performance of total environmental performance of house.house.

Documents

21 st -23 rd February 2007 NZSSES Conference, Auckland 2007 1 Sustainable choices for residential water supply in Auckland Sustainable choices for residential