Life Cycle Assessment of a New Zealand house

Barbara Nebel & Zsuzsa Szalay

Scion

“exemplar house”

Specifically designed as an example for research on residential costing (Willson 2002)

two storey design three bedrooms and a

garage total floor area of 195

m2

Building construction

suspended timber floor with foil / concrete slab on ground floor;

Light timber frame walls with fibre glass insulation, plasterboard internal lining with paint finish, external cladding weatherboard/ fibre cement/ brick;

pitched timber truss roof, flat ceiling with insulation lined with plasterboard, steel cladding/concrete tiles;

aluminium frame windows without thermal break.

Life Cycle Assessment

Life Cycle Assessment Framework

Goal and scope definition

Interpretation

Impact assessment

Inventory analysis

Direct applications:

• Product development and improvement

• Strategic planning

• Public policy making

• Marketing

• Other

Goal and Scope

Develop a generic LCA model for houses for research purposes

Compare six design alternatives Find the environmental hot-spots Analyse embodied and operational

environmental impacts

Functional unit: the Exemplar house over a 50-year period in New Zealand

Scenarios Six design alternatives

Three heating fuels: wood, gas, electricity Three locations: Auckland, Wellington, Queenstown

Name Floor Wall cladding Roof cladding Timber/WB/steel Suspended timber Weatherboard Steel Timber/FC/steel Suspended timber Fibrecement Steel Concrete/WB/steel Slab on ground

concrete Weatherboard Steel

Concrete/FC/steel Slab on ground concrete

Fibrecement Steel

Concrete/brick/steel Slab on ground concrete

Brick veneer Steel

Concrete/brick/concrete Slab on ground concrete

Brick veneer Concrete

Data

Average data from Europefor New Zealand only embodied energy and

CO2-emissions are available (Alcorn)

Data gaps:Dataset for carpet was based on GaBi data

and a European study (Potting 1994)Timber treatment is missing

Maintenance

Life time of building is 50 years Average life time of building elements based

on New Zealand and European data

Prorating was applied due to the high level of uncertaintiesLife time of building element is 20 yearsNumber of replacements:

50/20 -1 = ? 1.5

Operation

Hot water, ventilation, cooling, lighting, appliances not considered

Heating energy calculated with ALF3 (BRANZ) heating levels: 16, 18, 20 °C heating schedules: evening, morning and

evening, all day, 24 hour heating

Insulation as required by NZ Building Code

GaBi model

Production

Heating energy demand

Wellington, 24 hour heating, 20 °C

-10000

-5000

0

5000

10000

15000

20000

25000

Concrete/FC/steel

Timber/ FC/steel Concrete/WB/steel

Concrete/brick/steel

Concrete/brick/concrete

Timber/ WB/steel

En

erg

y b

alan

ce (

kWh

/yea

r)Floors Walls Windows Roof Air leakage Warm-up load Internal gains Solar gains

Wellington, evening heating only, 18 °C

-10000

-5000

0

5000

10000

15000

20000

25000

Concrete/FC/steel

Timber/ FC/steel Concrete/WB/steel

Concrete/brick/steel

Concrete/brick/concrete

Timber/ WB/steel

En

erg

y b

alan

ce (

kWh

/yea

r)

Floors Walls Windows Roof Air leakage Warm-up load Internal gains Solar gains

Evening heating, 18°C 24 hour heating, 20°C

Thermal mass

Influence of floor

0

2000

4000

6000

8000

10000

12000

14000

16000

18000

20000

Auckland, eveningheating only, 18 °C

Auckland, 24 hourheating, 20 °C

Queenstown, eveningheating only, 18 °C

Queenstown, 24 hourheating, 20 °C

En

erg

y d

eman

d (

kWh

/yea

r)

Timber/FC/steel Concrete/FC/steel Concrete/FC/steel no carpet

Impact categories

Non-renewable energy demand Renewable energy demand Global warming Ozone depletion Eutrophication Acidification Photo-oxidant formation

Building materials

Non-renewable energy content of building materials (MJ)

0

50000

100000

150000

200000

250000

300000

Con/FC/s teel

Tim /FC/s teel

Con/WB/s teel

Con/brick/s teel

Con/brick/con

Tim /WB/s teel

Malthoid

Paper

Paint

Gypsum board

Plas tics

Carpet

Fibre glass

Glass

Alum inium

Steel

MDF

Particleboard

Tim ber

Fibre cem ent

Brick

Plas ter

Gravel and sand

Concrete

Material quantities (kg)

0

20000

40000

60000

80000

100000

120000

140000

Con/FC/s teel

Tim /FC/s teel

Con/WB/s teel

Con/brick/s teel

Con/brick/con

Tim /WB/s teel

Malthoid

Paper

Paint

Gypsum board

Plas tics

Carpet

Fibre glass

Glass

Alum inium

Steel

MDF

Particleboard

Tim ber

Fibre cem ent

Brick

Plas ter

Gravel and sand

Concrete

Building elements

Non-renewable energy content of building elements (MJ)

0

50000

100000

150000

200000

250000

300000

Con/FC/steel

Tim/FC/steel

Con/WB/steel

Con/brick/steel

Con/brick/con

Tim/WB/steel

Plumbing

Stairs

Interior doors

Windows

Roof

Wall

Floors

Foundation

Wall components

Non-renewable energy content of wall components (MJ)

0

10000

20000

30000

40000

50000

60000

70000

80000

90000

Con/FC/s teel

Tim /FC/s teel

Con/WB/s teel

Con/brick/s teel

Con/brick/con

Tim /WB/s teel

Wallpaper

Paint

Gypsum board

Fibre glass

Steel bracing

Tim ber fram e

Paint

Weatherboards

Fibrecem ent

Brick cladding

Tim ber battens

Building paper

Foundation and floor

Non-renewable energy content of foundation and floor (MJ)

0

20000

40000

60000

80000

100000

120000

Con/FC/steel

Tim/FC/steel

Con/WB/steel

Con/brick/steel

Con/brick/con

Tim/WB/steel

Gypsum board

Paint

Fibre glass ins

Plaster

Timber frame

Steel

Timber nogging

Particleboard

Aluminum

Carpet Nylon

PVC vinyl

Timber

Steel

Gravel and sand

Polyethylene DPC

Concrete

PVC

Fibrecement

Roof components

Non-renewable energy content of roof components (MJ)

0

5000

10000

15000

20000

25000

30000

35000

40000

Con/FC/s teel

Tim /FC/s teel

Con/WB/s teel

Con/brick/s teel

Con/brick/con

Tim /WB/s teel

PVC spouting

Concrete tile

Colors teel roofing

Building paper

Steel

Tim ber fram e

Paint

PVC

Tim ber

Fibre cem ent

Life cycle energy

Non-renewable energy (MJ), Wellington electricity

0

200000

400000

600000

800000

1000000

1200000

Con/ FC/steel Tim/ FC/steel Con/ WB/steel Con/brick/steel

Con/brick/con

Tim/ WB/steel

Construction Maintenance Use End of life

Life cycle energy

Non-renewable energy (MJ)

0

200000

400000

600000

800000

1000000

1200000

1400000

1600000

1800000

End of life

Use

Maintenance

Construction

Timber/ WB/ steel

Environmental impacts

Timber/ WB/ steel, Wellington

Gas heating

Timber/WB/steel, Wellington gas

0%

10%

20%

30%

40%

50%

60%

70%

80%

90%

100%

Non-renew ableenergy

GWP ODP EP AP POCP

Construction Maintenance Use End of life

Timber/WB/steel, Wellington electricity

0%

10%

20%

30%

40%

50%

60%

70%

80%

90%

100%

Non-renew ableenergy

GWP ODP EP AP POCP

Construction Maintenance Use End of life

Timber/ WB/ steel, Wellington

Electric heating

Transport distances

Influence of transport distancesConcrete/FC/steel, Wellington electricity

0

20

40

60

80

100

120

Energy GWP ODP EP AP POCP

% o

f b

as

e s

ce

na

rio

Construction Maintenance Use End of life

100 km - 50 km - 200 km

Useful life of carpet

Influence of carpet lifeConcrete/FC/steel, Wellington electricity

0

20

40

60

80

100

120

Energy GWP ODP EP AP POCP

% o

f b

as

e s

ce

na

rio

Construction Maintenance Use End of life

10 years – 8 years – 15 years

Conclusions

For typical New Zealand heating level and schedule, materials have significant influence on life cycle results

Interesting results relating to thermal mass in intermittent heating schedule

Materials need to be looked at on component level

LCA is good tool to optimise building design

Tool can be used for other house designs based on data from quantitiy surveyor

Outlook

New Zealand inventory data for building materials

Insulation scenarios: NZS better and best practice

Statistical model to represent current building stock

Model retrofit of an existing house with insulation in walls

Futher information

Barbara Nebel, PhDGroupleader Sustainability FramworksSustainable Consumer ProductsPrivate Bag 3020, ROTORUA, New ZealandPhone +64 7 343 5637

Email: Barbara.nebel@scionresearch.com