6th-9th July 2004 NZSSES Conference, Auckland 2004 1

Optimum specification for Optimum specification for NZ HousesNZ Houses

Nalanie Mithraratne & Brenda Vale

School of ArchitectureSchool of Architecture

The University of AucklandThe University of Auckland

6th-9th July 2004 NZSSES Conference, Auckland 2004 2

World Primary Energy UseWorld Primary Energy Useby region (1971 – 1998)by region (1971 – 1998)

[Source: IPCC (2001)]

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Life Cycle Analysis ModelLife Cycle Analysis Model- - User InterfaceUser Interface

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NZS4218:1996NZS4218:1996

[Source: NZS 4218:1996]

Location Degree-days

Auckland 1151

Wellington 2054

Invercargill 2054

Christchurch 2424

[Source: ECCA (1994)]

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Construction typesConstruction types

Light:Light: timber framed construction. timber framed construction.

Concrete:Concrete: timber framed construction with timber framed construction with concrete floor.concrete floor.

Light-High:Light-High: timber framed construction with timber framed construction with additional insulation and double glazing.additional insulation and double glazing.

Concrete-High:Concrete-High: construction with additional construction with additional insulation and double glazinginsulation and double glazing..

Superinsulated:Superinsulated: timber framed construction timber framed construction with R 4.4mwith R 4.4m22..ooC/W all around and double C/W all around and double glazing.glazing.

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Orientation & LCE Orientation & LCE - - AucklandAuckland

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LIF

E C

YC

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N NW W SW S SE E NE

ORIENTATION

Light Concrete Superinsulated Light-High Concrete-High

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Orientation & LCEOrientation & LCE- Wellington- Wellington

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E C

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ORIENTATION

Light Concrete Superinsulated Light-High Concrete-High

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Orientation & LCE Orientation & LCE - Christchurch- Christchurch

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E C

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Light-High Concrete-High Superinsulated

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Construction type & LCEConstruction type & LCE

Construction type

Life cycle Energy (MJ/m2)

Auckland Wellington Christchurch

Light 17439 (+43%) 33910 (+68%) -

Concrete 16920 (+39%) 33609 (+67%) -

Superinsulated 12172 20153 22866

Light-High 14279 (+17%) 26701 (+33%) 31037 (+36%)

Concrete-High 13741 (+13%) 26350 (+31%) 30675 (+34%)

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Construction type & LCEConstruction type & LCE

Construction type

Life cycle Energy (MJ/m2)

Auckland Wellington Christchurch

Light 17439 (+22%) 33910 (+27%) -

Concrete 16920 (+19%) 33609 (+26%) -

Superinsulated 12172 (-15%) 20153 (-25%) 22866 (-26%)

Light-High 14279 26701 31037

Concrete-High 13741 (-4%) 26350 (-1%) 30675 (-1%)

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Energy prices & Life cycle cost Energy prices & Life cycle cost

Auckland Wellington Christchurch

Fixed Charge (cents/day)

57.03 72.75 (+27%) 56.21 (-1%)

Unit charge (cents/kWh)

14.51 14.86 (+2%) 15.43 (+6%)

[Source: Contact Energy (2004)]

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Initial and Life cycle cost Initial and Life cycle cost

Construction type

Auckland(NZ$/m2)

Wellington

(NZ$/m2)

Christchurch(NZ$/m2)

Initial cost

Life cycle cost

Initial cost

Life cycle cost

Initial cost

Life cycle cost

Light 672 967 640 1042 - -

Concrete 857 1085 816 1155 - -

Superinsulated 855 1119 815 1130 727 1038

Light-High 731 1007 697 1053 621 985

Concrete-High 923 1131 880 1171 785 1090

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LCC with 100% increase in energyLCC with 100% increase in energy

Construction type

Life Cycle Cost (NZ$/m2)

Year 0 Year 25 Year 50 Year 75 Year 100

Light 640 1019 1189 1235 1247 (+3%)

Concrete 816 1161 1308 1345 1356 (+11%)

Superinsulated 815 1072 1191 1229 1239 (+2%)

Light-High 697 1005 1154 1198 1209

Concrete-High 880 1153 1279 1314 1322 (+9%)

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ConclusionsConclusions

Price of energy significantly impact the Price of energy significantly impact the life cycle cost.life cycle cost.

Use of higher performance requirements Use of higher performance requirements currently specified for colder region currently specified for colder region throughout NZ could reduce the energy throughout NZ could reduce the energy use dramatically at a marginal increase use dramatically at a marginal increase in initial cost.in initial cost.