Life Cycle Assessment of University Buildings Case Studies in NTU, SingaporeEnergy Smart, Research & Innovation.

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Prof Justin Dauwels Ms Priyanka Mehta Mr Shi WenyongMr Chang Chia Chien

Team members:Energy Research Institute @ NTU (ERI@N)1 CleanTech Loop, #06-04 CleanTech One, Singapore 637141Phone: (65) 6592 1786 / 2468 Fax: (65) 6694 6217

* Contents

• NTU Embodied Energy Study• Background Information• Scopes andmethodology

• Results and Findings• Overall material embodied energyresults• Case study on Prefabricated Prevolumetric Volumetric

Construction (PPVC) steel and wooden buildings• Case study on a low energy tropical building

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1. Product Stage

Life Cycle of Buildings

2. Construction Stage

3. Use Stage

4. End of LifeStageOperational

Energy3

Building life cycle energy is the energy required for the whole life cycle of the building

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Embodied Energy (EE) vs Operational Energy(OE)

Percentage of EE increases with improved OE efficiency Source: P. Chastas et al. / Building and Environment 105 (2016) 267-282

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Source: M. Cellura et al. / Energy and Buildings 72 (2014)

Cold climate: Lower Embodied Energy

Hot climate: Higher Embodied Energy

Embodied Energy (EE) vs Operational Energy(OE)

Scopes, methodologies and data sources

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Embodied Energy Study Scopes

Roof

Ceilings

Floors

External Walls

Windows

Internal Walls

8*Excluding foundation, doors, furniture and other minor building materials.

Superstructure is the part of the building above the ground levelExamples:

Study Scope: Superstructure

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Building Information Modelling (BIM)

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Material Embodied

Energy/ Embodied

Carbon

MaterialQuantity

Embodied Energy/ Carbon

Coefficients

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Methodologies and Data Sources

Results and findings

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Case Study 1:

NTU 22 Case Study Buildings

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Study Scopes include:

• 22 academic buildings (Excluding residential halls)• Only structural system• All life cycle stages• 3 main building materials like concrete, steel and glass• Other building materials like plaster, wood, aluminium

Study Scopes

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*Accurate as of 24 April 2019

Material6%

Construction0.3%

Transportation1%

Operational90%

Maintenance2.4%

End of Life0.3%

Based on a 40 year lifetime

Average Life Cycle Energy: 12,210 kWh/m2

Average Operational Energy: 11,033 kWh/ m2

Average Embodied Energy: 1177 kWh/ m2

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* Units are in kWh per Gross Floor Area (GFA)

Overall Results

Material Embodied Energy (EE) (kWh/m2.yr)

*Accurate as of 24 April 201915

0

5

10

15

20

25

30

NTU Buildings

Concrete, Steel and Glass Other materials

Percentage Breakdown of Embodied Energy (EE)

*Accurate as of 24 April 201916

0%

10%

20%

30%

40%

50%

60%

70%

80%

90%

100%

Material Construction Transportation Maintenance End of Life

*Accurate as of 24 April 201917

Academic Buildings (Operational Energy)

0

100

200

300

400

500

600

700

Energy (k

Wh/m

2 . year

)

NTU Buildings

Case Study 2:

NTU PPVC and Wood Buildings

Special Construction Method

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Steel vs Concrete Timber vs Concrete

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NTU Nanyang Crescent Halls (Student Residential Halls)

Material: Steel PPVC

NTU Wave Sports Hall

Material: Laminated Timber

Non-conventional Building Materials

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Prefabricated Prefinished Volumetric Construction

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Benefits and disadvantages of using PPVC

Benefits• Reduce construction time• Minimize noise and dust • Better safety for workers • Greater sustainability (Example: Use of green concrete)

Disadvantages• Require different moulds for different PPVC modules• Transportation: Limited numbers of module per trip• Require storage space for module

Source: https://surbanajurong.com/wp‐content/uploads/2018/08/1.‐PPVC‐Final‐.pdf

Building Material EE in kWh/m2

Without steel recyclingBuilding Material EE in kWh/m2

With steel recycling

0

200

400

600

800

1000

1200

1400

1600

1800

Steel PPVC RC PPVC0

200

400

600

800

1000

1200

1400

1600

1800

Steel PPVC RC PPVC

*Accurate as of 24 April 201923*RC PPVC contains reinforcement steel

Steel PPVC vs Reinforced Concrete (RC) PPVC

Steel PPVC has lower material embodied energy (Material EE) than RC PPVC when considering recycling

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86%

14%

Life Cycle Energy (Steel PPVC)

Operational Energy Embodied Energy

83%

17%

Life Cycle Energy (RC PPVC)

Operational Energy Embodied Energy

*Accurate as of 24 April 201924

Steel PPVC vs Reinforced Concrete (RC) PPVC

Building life cycle energy is the energy required for the whole life cycle of the building

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Timber vs Concrete

NTU Wave Sports Hall

Material: Laminated Timber

NTU Old Sports Hall

Material: Concrete and Brick/Mortar

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Wood

Laminated Timber Softwood

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Mainly include • non-renewable fossil fuel consumption• renewable biomass (especially for wood)• non-renewable nuclear• renewable solar/wind/water/geothermal

* For biomass energy, based on UK Inventory Carbon of Energy and Alice et al., energy from biomass could be excluded from EE calculation.

Primary energy of material

*

*Accurate as of 24 April 201928

Source: From various Environmental Product Declaration (EPD) of material, UK Inventory Carbon of Energy 

*Primary energy only considered the material stage

EE of Laminated Timber is slightly higher than of concrete

*

0

100

200

300

400

500

600

NTU Timber Sports Hall NTU Concrete Sports Hall

Material Embodied Energy per m2 (kWh/m2)

Concrete  Steel Glass Wood Brick and Mortar

*Accurate as of 24 April 201929

Timber vs Concrete

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Benefits of using Wood • Fast installation and construction time (Mass Engineered Timber)

• Better insulator for energy efficiency (than steel/plastic)

• Less waste produced during production and deconstruction

• Waste water production is lower during manufacturing

• Design versatility

Case Study 3:

NTU Low Energy Building (NTU Academic Building North)

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NTU Academic Building North

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Study Scopes:

1. Structural System2. Finishes3. Heating, Ventilation

and Air Conditioning System (HVAC)

4. Lighting System5. Plumbing System 6. Fire Sprinkler

System

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*Accurate as of 24 April 2019

24%

1%3%

61%

9%2%

Material Construction Transportation Operational Maintenance End of Life

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Overall Life Cycle Energy Breakdown

Material and maintenance EE are the top 2 contributors of EE

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*Accurate as of 24 April 201934

Material and MaintenanceEmbodied Energy Breakdown

Structural 62%

Finishes21%

HVAC12%

Lighting4%

Plumbing0.5%

Fire Sprinkler0.5%

• Embodied Energy (EE) forms a sizeable percentage of the overall life cycle energy of buildings

• The percentage of EE in tropical buildings and low energy buildings are relatively higher.

• More future EE studies should focus on other types of buildings like residential and commercial buildings.

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Conclusion

Energy Research Institute @ NTU (ERI@N)1 CleanTech Loop, #06-04 CleanTech One, Singapore 637141Phone: (65) 6592 1786 / 2468 Fax: (65) 6694 6217

For further information please contact:Executive-Director ERI@NEmail: D-ERIAN@ntu.edu.sg

http://erian.ntu.edu.sgThank you!

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