timber framed house life cycle investigation

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1 Timber-framed house Life-cycle investigation The use of timber, instead of other construction materials, has the potential to have a more positive environmental impact on the life-cycle of a domestic dwelling”. The aim of this report is to investigate the accuracy of this hypothesis. Abstract The environmental impacts of using timber in construction has been investigated by researching and analyzing the different factors related to answering the hypothesis. The designs for a timber-framed domestic dwelling was collected from ‘Southern Timber Frame Ltd’ to calculate the embodied energy. A quantity survey was undertaken to establish the materials and quantities used to construct the building, then an analysis of the embodied energy was carried out. Final results saw an embodied energy of 30,595kgCO 2. This figure was compared with other structures to reveal that embodied energy increases with the weight of structure. Operational carbon emissions were also investigated for differing structures to show that this decreases with increasing weight of structure. The greatest factor influencing total life-cycle emissions was the operational energy. There is a positive correlation between weight of structure and total emissions, concluding that heavier-weight structures produce fewer carbon emissions throughout their life-cycle.

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Page 1: Timber framed house life cycle investigation

1

Danie

l Palm

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10122478/A

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604

Timber-framed house Life-cycle investigation

“The use of timber, instead of other construction materials, has the potential

to have a more positive environmental impact on the life-cycle of a domestic

dwelling”. The aim of this report is to investigate the accuracy of this

hypothesis.

Abstract

The environmental impacts of using timber in construction has been

investigated by researching and analyzing the different factors related to

answering the hypothesis.

The designs for a timber-framed domestic dwelling was collected from

‘Southern Timber Frame Ltd’ to calculate the embodied energy. A quantity

survey was undertaken to establish the materials and quantities used to

construct the building, then an analysis of the embodied energy was carried

out. Final results saw an embodied energy of 30,595kgCO2.

This figure was compared with other structures to reveal that embodied energy

increases with the weight of structure. Operational carbon emissions were also

investigated for differing structures to show that this decreases with increasing

weight of structure. The greatest factor influencing total life-cycle emissions

was the operational energy. There is a positive correlation between weight of

structure and total emissions, concluding that heavier-weight structures

produce fewer carbon emissions throughout their life-cycle.

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Introduction

It is clear that global warming needs to be addressed in order to solve the many

problems attributed to it. Unfortunately, removing the causes of such a

phenomena is easier said than done. It is first necessary to understand what is

causing the climate of planet Earth to heat up at such a rate and then find out

who or what is responsible. Only then can strategies be put in place to reduce

the subsequent effects that are degrading our only habitat.

Limiting our impacts on the environment is vital in order to provide our future

generations a desirable place to live.

Governments have discovered that the global construction industry is

responsible for 30% of the global greenhouse gas emissions, suggesting that this

sector is most responsible.

This paper investigates how we, as a nation, can reduce our carbon footprint by

identifying the stages of construction and materials used that have the greatest

effect on the environment.

The hypothesis that environmental impacts can be reduced by using timber in a

dwelling construction, will be explored.

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Methodology

To investigate the embodied energy of a timber-framed domestic dwelling by

determining the energy used to manufacture it.

The aim and objectives of the investigation have been outlined. Research

techniques and methods have also been evaluated to ensure the data collected

is relevant and can be analysed appropriately to come to a conclusion. A

description of how the results will be displayed have then been outlined.

Aim

To investigate the embodied energy of a timber-framed domestic dwelling by

determining the energy used to manufacture it.

Objectives

This is primary research, from which, Quantitative data will be collected from a

real-life case study. Local companies that specialize in timber-frame

manufacturing will be contacted to request designs of a domestic dwelling

constructed of timber. Emails will be distributed asking for technical drawings

in an ‘Autodesk AutoCAD’ format to display different layouts. (Appendix B

shows how the results were extracted).

From here, a quantity survey can be undertaken to determine the amount of

each material used within the construction. Further quantitative data on

embodied energy of materials will be collected from the ‘Inventory of Carbon

and Energy’ (ICE) which has been produced by the ‘University of Bath’. This

database provides density figures that have been extracted from the Chartered

Institution of Building Services Engineers (CIBSE) guide. Assumptions in the

exact material used may be implemented if there are any limitations in the

collected data.

Results are to be displayed in a table that was created in a ‘Microsoft Excel’

spreadsheet to reveal how each step was calculated. This data can be

compared by using bar charts and pie charts to show which component

produces the most embodied carbon. It will also be important to compare the

embodied carbon and relative mass of the material investigated. This can

determine the relative environmental impact of each material, regardless of

the mass used.

The case study timber-framed house will be divided into six separate

components to help make it simpler to analyse: External walls, Floors, Party

wall, Load-bearing walls, Non load-bearing walls and Roof.

The process used to calculate the embodied energy used is highlighted.

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Cross-sectional area

The first calculation was to determine the cross-sectional area of an element.

The cross-sectional area will be calculated by using the measuring tool on the

technical drawings, or by making assumptions based on appropriate products

that could be used in their place. These products were identified on various

manufacturer websites that contain specifications of their products.

𝐂𝐫𝐨𝐬𝐬 𝐒𝐞𝐜𝐭𝐢𝐨𝐧𝐚𝐥 𝐚𝐫𝐞𝐚 (𝐦𝟐) = Width (m) 𝑥 Height (m)

Volume

Calculated by multiplying the cross-sectional area by the length, which was

determined by measuring up the technical drawings.

𝐕𝐨𝐥𝐮𝐦𝐞 (𝐦𝟑) = Cross sectional area (m2) 𝑥 Length (m)

Mass

Determined by multiplying the already calculated volume, by the density

figures collected from the ‘ICE’.

𝐌𝐚𝐬𝐬 (𝐤𝐠) = Density (kg

m3) 𝑥 Volume (m3)

Embodied Carbon of item

The embodied carbon of the individual item was calculated by using data from

the ‘ICE database’ and is multiplied by the mass.

𝐓𝐨𝐭𝐚𝐥 𝐄𝐦𝐛𝐨𝐝𝐢𝐞𝐝 𝐂𝐚𝐫𝐛𝐨𝐧 (𝐤𝐠𝐂𝐎𝟐) = Embodied carbon (kgCO2

kg) 𝑥 Mass (kg)

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Results

Collected Data

Section

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GF Soleplate layout

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FF Soleplate layout

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GF Wall layout

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FF Wall layout

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FF Joist layout

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Roof layout

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Section AA

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Section BB

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Embodied Energy calculations

External walls

Item Material Density (kg/m3)

U-value (W/mk)

Cross-

sectional area (m2)

Total

volume (m3)

Total Mass (kg)

Relative

Embodied Carbon

(kgCO2/kg)

Embodied

Carbon of item

(kgCO2)

CLS Profile Sawn softwood 500 0.12 0.0053 1.89 947.0 0.43 407.2

Soleplate channel Galvanised steel 7850 29 0.0003 0.00 36.7 1.82 66.9

Sheathing Hardboard 600 0.08 0.0090 0.86 518.4 1.23 637.6

Service batten Sawn softwood 500 0.12 0.0010 0.34 169.1 0.43 72.7

Lintel Glulam timber 490 0.12 0.0088 0.32 154.8 0.60 92.9

Breather membrane Polypropylene 950 0.2 0.0006 0.06 54.7 0.24 13.1

Internal lining board Plasterboard 800 0.16 0.0090 0.86 691.2 0.24 165.9

DPC Polyethelene 950 0.7 0.0003 0.01 4.8 8.28 39.3

Nail 1 Galvanised Steel 7850 29 0.0025 - 7.1 1.82 13.0

Nail 2 Galvanised Steel 7850 29 0.0100 - 11.9 1.82 21.6

Insulation Rock wool 60 0.033 - 14.42 865.2 1.16 1003.6

Brick Clay and mortar 1700 0.84 0.1000 12.00 20400.0 0.20 4080.0

Block Concrete block 1350 0.6 0.0210 0.42 567.0 0.14 81.1

Door 1 Sawn hardwood 700 0.17 0.5292 0.53 370.4 0.46 170.4

Door 2 Sawn hardwood 700 0.17 0.2940 0.29 205.8 0.46 94.7

Window 1 Double-glazing 140 0.048 0.0015 0.01 1.1 0.76 0.8

Window 2 Double-glazing 140 0.048 0.0013 0.00 0.4 0.76 0.3

Window 3 Double-glazing 140 0.048 0.0005 0.00 0.1 0.76 0.05

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Party wall

Item Material Density

(kg/m3)

U-value

(W/mk)

Cross-

sectional area (m2)

Total

volume (m3)

Total Mass

(kg)

Relative Embodied

Carbon (kgCO2/kg)

Embodied Carbon of

item (kgCO2)

CLS Profile Sawn softwood 500 0.12 0.0034 1.03 513.0 0.43 220.6

Soleplate channel Galvanised steel 7850 29 0.0003 0.00 18.4 1.82 33.4

Sheathing Hardboard 600 0.08 0.0090 0.09 54.0 1.23 66.4

Internal lining board

Plasterboard 800 0.16 0.0090 0.09 72.0 0.24 17.3

Nail 1 Galvanised Steel 7850 29 0.0025 - 0.5 1.82 1.0

Nail 2 Galvanised Steel 7850 29 0.0100 - 5.3 1.82 9.6

Insulation Rock wool 60 0.033 0.1400 8.68 520.8 1.16 604.1

Block Concrete block 1350 0.6 0.1350 1.22 1640.3 0.14 234.6

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Load-bearing walls

Item Material Density

(kg/m3)

U-value

(W/mk)

Cross-

sectional area (m2)

Total

volume (m3)

Total Mass

(kg)

Relative Embodied

Carbon (kgCO2/kg)

Embodied Carbon of

item (kgCO2)

CLS Profile Sawn softwood 500 0.12 - 0.32 160.5 0.43 69.0

Soleplate channel Galvanised steel 7850 29 0.0002 0.00 19.0 1.82 34.6

Lintel Glulam timber 490 0.12 - 0.05 26.0 0.60 15.6

Internal lining board

Plasterboard 800 0.16 0.0090 0.20 158.4 0.24 38.0

Nail Galvanised Steel 7850 29 0.0100 - 3.1 1.82 5.6

Door Sawn softwood 500 0.12 0.0210 0.04 21.0 0.43 9.0

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Non load-bearing walls

Item Material Density

(kg/m3)

U-value

(W/mk)

Cross-

sectional area (m2)

Total

volume (m3)

Total Mass

(kg)

Relative Embodied

Carbon (kgCO2/kg)

Embodied Carbon of

item (kgCO2)

CLS Profile Sawn softwood 500 0.12 - 0.74 369.5 0.43 158.9

Nail Galvanised Steel 7850 29 0.0100 - 7.2 1.82 13.1

Soleplate channel Galvanised steel 7850 29 0.0002 0.01 44.9 1.82 81.7

Internal lining board

Plasterboard 800 0.16 0.0090 0.47 374.4 0.24 89.9

Door 1 Sawn softwood 500 0.12 0.0280 0.06 28.0 0.43 12.0

Door 2 Sawn softwood 500 0.12 0.0260 0.08 39.0 0.43 16.8

Door 3 Sawn softwood 500 0.12 0.0210 0.04 21.0 0.43 9.0

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Floors

Item Material Density

(kg/m3)

U-value

(W/mk)

Cross-

sectional area (m2)

Total

volume (m3)

Total Mass

(kg)

Relative Embodied

Carbon (kgCO2/kg)

Embodied Carbon of

item (kgCO2)

JJI Joist Flange Sawn hardwood 700 0.17 0.0042 0.38 266.5 0.46 122.6

JJI Joist Board Hardboard 600 0.08 0.0019 0.17 99.9 1.23 122.9

Header Sawn softwood 500 0.12 0.0093 0.30 149.0 0.43 64.1

Beams Glulam timber 490 0.12 0.0110 0.09 45.8 0.60 27.5

JJI Hangers Galvanised steel 7850 29 - - 1.0 1.82 1.8

Nail 1 Galvanised Steel 7850 29 0.0025 - 1.5 1.82 2.7

Nail 2 Galvanised Steel 7850 29 0.0100 - 5.0 1.82 9.1

DPM Polyethelene 950 0.7 0.0003 0.02 21.1 8.28 174.4

Floorboard Particleboard 750 0.1 0.0220 1.95 1463.6 0.49 717.1

Internal lining board

Plasterboard 800 0.16 0.0090 0.80 638.6 0.24 153.3

Beam Pre-cast

concrete 1050 0.32 0.1600 15.00 15750.0 0.22 3386.3

Block Pre-cast concrete

1050 0.32 0.3700 34.60 36330.0 0.22 7811.0

Insulation Rock wool 60 0.033 0.1400 12.42 745.1 1.16 864.3

Screed Cement screed 2100 1.4 0.0650 5.77 12107.6 0.22 2712.1

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Roof

Item Material Density (kg/m3) U-value

(W/mk)

Cross-

sectional area (m2)

Total

volume (m3)

Total Mass

(kg)

Relative Embodied

Carbon (kgCO2/kg)

Embodied Carbon of

item (kgCO2)

Truss rafter T01 Sawn hardwood 700 0.17 0.0035 0.11 78.4 0.46 36.1

Truss ceiling joist T01

Sawn hardwood 700 0.17 0.0035 0.08 58.8 0.46 27.0

Truss rafter T02 Sawn hardwood 700 0.17 0.0035 0.25 176.4 0.46 81.1

Truss ceiling joist T02

Sawn hardwood 700 0.17 0.0035 0.19 132.3 0.46 60.9

Rafter Sawn hardwood 700 0.17 0.0053 0.05 35.0 0.46 16.1

Girder truss GT01 Sawn hardwood 700 0.17 0.0035 0.03 19.6 0.46 9.0

Ridge plate Sawn hardwood 700 0.17 0.0089 0.11 75.0 0.46 34.5

Wall plate Sawn hardwood 700 0.17 0.0035 0.10 71.1 0.46 32.7

Lay board Sawn hardwood 700 0.17 0.0053 0.04 29.8 0.46 13.7

Truss hangers Galvanised Steel 7850 29 - - 1.6 1.82 3.0

Ceiling insulation Rock wool 60 0.033 0.1400 0.63 37.8 1.16 43.8

Breather membrane Polyproplene 950 0.2 0.0003 0.02 17.3 8.28 143.6

Roof tiles Clay 1890 0.8 0.0005 2.11 11500.0 0.43 4945.0

Battens Sawn hardwood 700 0.17 0.0010 0.69 485.5 0.46 223.3

Fascia Sawn hardwood 700 0.17 0.0035 0.08 58.8 0.46 27.0

Soffit Sawn hardwood 700 0.17 0.0035 0.08 58.8 0.46 27.0

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Summary

Component Embodied Carbon (kgCO2)

External Walls 6961.14

Party wall 1186.97

Load-bearing walls 234.39

Non load-bearing walls 575.12

Floors 16169.10

Roof 5723.89

TOTAL 30595

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Material Total (kg) % Total

(kgCO2) %

Relative Embodied Carbon per weight

Sawn Softwood 2417.06 2.21 1039.34 3.40 5947.85

Sawn Hardwood

2122.14 1.94 976.18 3.19 5236.89

Glulam timber 226.58 0.21 135.95 0.44 286.98

Particleboard 1463.55 1.34 717.14 2.34 3144.55

Hardboard 672.30 0.61 826.93 2.70 2907.40

Galvanised Steel

163.20 0.15 297.03 0.97 451.58

Concrete block 2207.25 2.01 315.64 1.03 2532.89

Pre-cast concrete

52080.00 47.53 11197.20 36.60 461886.21

Cement screed 12107.55 11.05 2712.09 8.86 36149.42

Clay 11500.00 10.50 4945.00 16.16 91426.77

Rock wool 2168.88 1.98 2515.90 8.22 22858.22

Polyethylene 25.82 0.02 213.76 0.70 175.17

Polypropylene 72.06 0.07 156.69 0.51 152.30

Plasterboard 1934.64 1.77 464.31 1.52 2639.30

Clay and

mortar 20400.00 18.62 4080.00 13.34 74810.16

Double glazing 1.49 0.00 1.13 0.00 1.50

TOTAL 109562.52 100 30594.29 100 710607.18

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Graphics

0.0

500.0

1000.0

1500.0

2000.0

2500.0

3000.0

3500.0

4000.0

4500.0

Emb

od

ied

Car

bo

n (

kgC

O2)

Item

Material Breakdown of Embodied Carbon in External walls

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0.0

100.0

200.0

300.0

400.0

500.0

600.0

700.0

CLS profile Soleplate channel SheathingInternal lining board Nail 1 Nail 2 Insulation Block

Emb

od

ied

Car

bo

n (

kgC

O2)

Item

Material Breakdown of Embodied Carbon in Party wall

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0.0

10.0

20.0

30.0

40.0

50.0

60.0

70.0

80.0

CLSprofile

Soleplatechannel

Lintel Internalliningboard

Nail Door

Emb

od

ied

Car

bo

n (

kgC

O2)

Item

Material Breakdown of Embodied Carbon in Load-bearing walls

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0.0

20.0

40.0

60.0

80.0

100.0

120.0

140.0

160.0

180.0

CLS profile Nail Soleplate channel Internal lining board Door 1 Door 2 Door 3

Emb

od

ied

Car

bo

n (

kgC

O2)

Item

Material Breakdown of Embodied Carbon in Non Load-bearing walls

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0.0

1000.0

2000.0

3000.0

4000.0

5000.0

6000.0Em

bo

die

d C

arb

on

(kg

CO

2)

Item

Material Breakdown of Embodied Carbon in Roof

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0.0

1000.0

2000.0

3000.0

4000.0

5000.0

6000.0

7000.0

8000.0

9000.0Em

bo

die

d C

arb

on

(kg

CO

2)

Item

Material Breakdown of Embodied Carbon in Floors

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6961.14

1186.97

234.39

575.12

16169.10

5723.89

Component Breakdown of Embodied Carbon in Timber-framed House (kgCO2)

External Walls Party wall Load-bearing walls Non load-bearing walls Floors Roof

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1039.34 976.18

135.95

717.14 826.93

297.03 315.64

11197.20

2712.09

4945.00

2515.90

213.76 156.69464.31

4080.00

1.130.00

2000.00

4000.00

6000.00

8000.00

10000.00

12000.00Em

bo

die

d C

arb

on

(kg

CO

2)

Material

Total Embodied Carbon of Building Materials

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2417.06 2122.14226.58

1463.55 672.30 163.202207.25

52080.00

12107.5511500.00

2168.8825.82 72.06

1934.64

20400.00

1.490.00

10000.00

20000.00

30000.00

40000.00

50000.00

60000.00M

ass

(kg)

Material

Total Mass of Building Materials

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461886.21

36149.42

91426.77

74810.16

Total Mass with Relative Embodied Carbon

Sawn Softwood Sawn Hardwood Glulam timber Particleboard Hardboard Galvanised Steel

Concrete block Pre-cast concrete Cement screed Clay Rock wool Polyethylene

Polypropylene Plasterboard Clay and mortar Double glazing

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5947.85 5236.89 286.98 3144.55 2907.40 451.58 2532.89

461886.21

36149.42

91426.77

22858.22

175.17 152.30 2639.30

74810.16

1.500.00

50000.00

100000.00

150000.00

200000.00

250000.00

300000.00

350000.00

400000.00

450000.00

500000.00

Material

Total Mass with Relative Embodied Carbon

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Discussion

The overall embodied carbon of the timber framed house was 30,595 kgCO2.

Split up into components, the floors (16,169.1 kgCO2) had the greatest impact

and the internal walls (809.51 kgCO2) had the least. The results table suggests

that this is because the ground floor is composed of pre-cast concrete, which is

responsible for a significant proportion of the overall impact.

Pre-cast concrete, as a material, contributes the most to embodied impact with

11,197.2 kgCO2, which is 36.6% of the total embodied carbon. The clay tiles and

external brickwork are 2nd and 3rd with 4,945 kgCO2 (16.16%) and 4,080 kgCO2

(13.34%) respectively. On the other hand, the double glazing and glulam timber

had the least embodied impact with 1.13 kgCO2 (0.001%) and 135.95 kgCO2

(0.44%) respectively. Other materials with negligible impacts included

polypropylene (156.69 kgCO2), polyethylene (213.76 kgCO2), galvanized steel

(297.03 kgCO2), concrete block (315.64 kgCO2), and plasterboard (464.31

kgCO2).

When the embodied impact of the materials were adjusted to take relative

mass into consideration, pre-cast concrete, clay, cement screed, brickwork and

Rockwool presented the greatest impact. Pre-cast concrete was still the most

significant, with figures of five times greater than clay per unit of mass.

Of all the timber products, sawn softwood (1039.34 kgCO2) had the greatest

embodied impact, then sawn hardwood (976.18 kgCO2), hardboard (826.93

kgCO2), particleboard (717.14 kgCO2) and glulam (135.95 kgCO2). When relative

mass was calculated, Sawn softwood was still the most detrimental towards the

environment of all the timber products. Sawn hardwood, particleboard,

hardboard and glulam followed closely.

Overall, the timber products contributed 12.07% to total embodied impact with

6.31% of the total mass, which suggests they had a greater impact on the

environment per relative unit of mass compared to other materials.

These results do not correlate with the life-cycle assessment that was

undertaken in the first stage. Those results suggested that the hardwood posed

the greatest threat, with sawn softwood the least. This could be because the

life-cycle stages were different, or data was collected from a different source.

However, differences in both investigations were negligible.

Analysis for the different building components will now be discussed.

External walls

The external brickwork (4080 kgCO2) presents the greatest impact for this

component with other significant contributors being the insulation (1003.6

Page 34: Timber framed house life cycle investigation

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kgCO2), OSB sheathing (637.6 kgCO2) and CLS profile (407.2 kgCO2). This is

probably because the brickwork has a large mass compared with the other

materials used.

Party wall

The insulation (604.1 kgCO2) had the biggest embodied impact, probably due to

the amount used in the party wall (520kg). Other materials with significant

impact include block (234.6 kgCO2) and the CLS Profile (220.6 kgCO2).

Load-bearing walls

The CLS profile saw the greatest impact (69 kgCO2), with the internal lining

board (38 kgCO2) and soleplate channel (34.6 kgCO2) being other significant

contributors.

Non load-bearing walls

The same three materials contributed the most to this building component. CLS

profile (158.9 kgCO2), internal lining board (89.9 kgCO2) and soleplate channel

(81.7 kgCO2).

Floors

The concrete block (7811 kgCO2) and beam (3386.3 kgCO2) were the greatest

contributors in the flooring, with screed (2712.1 kgCO2) closely following.

Roof

The clay tiles were the only material that significantly contributed to overall

impact, being responsible for (4945 kgCO2).

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Conclusion

Environmental impacts of timber

Overall, the results show that there is a potential to significantly reduce the

environmental impact during the ‘cradle-to-site’ stages of the lifecycle, by

using timber products (-0.41 to 1.24), compared to galvanized steel (4.1).

There are many environmental impact parameters to consider when

determining the overall effect of producing a product and it is possible to

identify them by undertaking a Life cycle assessment.

The results from the Life cycle assessment revealed that the type of timber

used has varying degrees of impact. The greatest environmental impacts were

on the ‘Global warming potential’ and ‘Acidification potential’ parameters,

which means that the production of timber has a compelling impact towards:

The quantity of greenhouse gases in the atmosphere.

The quantity of substances emitted into the atmosphere that results in

acid rain.

On the other hand, the parameters that seemed to have no significant impact

were ‘Ozone depletion potential’, ‘Abiotic depletion potential’, and ‘Waste

disposed’. This suggests that the production of timber presents no significant

threat towards:

The thinning of the stratospheric ozone layer through emissions.

The consumption of non-renewable energy.

The filling of landfills and other disposal sites.

The use of steel and the wood adhesive tend to have a significant impact on the

environment, affecting ‘Global warming potential’, ‘Eutrophication potential’,

‘Photochemical ozone layer creation potential’ and ‘Waste disposed’.

Thermal Efficiency

The thermal efficiency of a building can heavily contribute to the life-cycle

emissions of a building. The U-values of building components must be

considered to minimize the amount of heat lost and therefore, the operational

emissions used to reheat the interior space.

Thermal efficiencies of different building constructions do not vary significantly

and may have no apparent effect on the operational energy consumption.

Page 36: Timber framed house life cycle investigation

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Total life-cycle emissions

It is important to carefully design the construction of the floors, external walls

and roof, because these components tend to have the greatest contribution to

the embodied carbon in all cases. There tends to be a positive correlation

between embodied carbon and weight of structure but it has been identified

that timber and concrete components of a typical new UK house were the only

significant contributors to the overall embodied CO2 content of the building.

In all cases investigated, the heavier weight structures saw a decrease in

overall emissions than the light weight, timber-framed structure because they

were more adapted to warmer summers. A decrease in overall CO2 emissions

can be achieved by focusing on the operational phase, because no results were

found in which initial embodied carbon emissions outweighed the operational

emission savings due to the thermal massing effects. Unfortunately,

consumption if climate change is not taken into account, then this thermal

massing seems to have no bearing on total operational energy emissions.

Buildings of different form and usage type will have different requirements for

energy usage, however, it is clear that a decrease in operational energy is likely

to cause an increase in embodied energy.

It seems that the use of timber and light weight structures has the potential to

reduce embodied energy of domestic dwellings and the initial environmental

impact of using this material tends to be less problematic compared to other

building materials. However, this impact is offset during the operational phase

of a building, where more harm is done in an attempt to maintain indoor

comfort levels throughout its life. The overall emissions and environmental

impact through all the relevant parameters can be reduced by using heavier

weight structures, as their ability to passively control the conditions using

thermal mass properties are so great and relevant for our changing climate.

If the data collected from the literature survey, in respect to global warming

impacts are to be believed, then temperatures will significantly rise over the

century and techniques must be found to adapt to the changes. In order to

reach the targets that the UK government agreed to in the Kyoto Protocol,

further research and planning must be made in this area to reduce the lifecycle

emissions of domestic dwellings.

As a result, architects should answer the global warming situation by focusing

on the operational energy savings when designing a construction. To achieve

higher levels of indoor comfort and reduced lifecycle CO2 emissions in warming

climates, it seems necessary to implement passive and active cooling measures

with a medium to heavyweight construction.

Page 37: Timber framed house life cycle investigation

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Unfortunately, further research needs to be undertaken to clarify what the

optimum type of structure is for constructing domestic dwellings with an aim to

achieve the least carbon emissions throughout the lifecycle.