# Carbon Footprint Calculations And Analysis Engineering Essay

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Carbon footprint is an objective way of determining how much of greenhouse gas (GHG) is being emitted from a process, organisation, event or product either directly or indirectly. The amount of GHG has great impacts on climate change and global warming (carbon trust, 2011). Calculating the carbon footprint of construction works is an important tool to enable builders evaluate the options of what building components/materials to use offering the same quality/value but with a less overall effect on the environment. This paper makes a comparison in the construction of a floor area or dimension 20m by 30m using two different types of materials; concrete (cement based) and wood. A comparison is made on the overall footprint of both after considering the various type of materials used in both cases.

## CONCRETE FLOOR

A concrete floor is comprised of the following basic components according to Detail Design Online (2011):

Screed (50mm)

Concrete slab (100mm)

Insulation (Rockwool) (50mm)

Damp proof membrane.

The carbon footprints of these components are calculated individually thus:

Screed

According to DIY (2009), screed can be made by using 3 part sand and 1 part cement; this was as well assumed to be equivalent to a 1:3 mortar of cement:sand mix.

Volume of screed=Floor Area*thickness of screed

=20*30*0.05=30m3

Density of Screed (mortar) =2.2tonnes/m3 (CCC)

Mass of mortar for screed =30*2.2 (volume*Density)

=66tonnes

Considering 10% waste =72.6tonnes

Embodied carbon of Screed =72.6*0.21 (Mass of material*embodied tCO2/t of material (CCC))

=15.25tCO2

Distance from Green Circle concrete in Barry 12. 4km

Concrete slab

The floor area is assumed to be one of such that is not exposed to any type of corrosion; therefore the concrete type used is XO (CCC).

Volume of concrete slab =Floor Area*thickness of concrete

=20*30*0.1 =60m3

Density of concrete =2.4tonnes/m3 (CCC)

Mass of concrete =60*2.4=144tonnes

Considering 10% waste =158.4tonnes

Embodied carbon of Concrete =158.4*0.078(CCC) =12.36tCO2

Distance from Green Circle concrete in Barry 12. 4km

Insulation (Rockwool)

Volume of insulation=Floor Area*thickness of insulation

=20*30*0.05=30m3

Density of insulation =100kg/m3 (ICE)

Mass of insulation =30*100 =3000kg =3tonnes

Considering 10% waste =3.3 tones

Rockwool embodied carbon =1.05t CO2/t (Cradle to Site)

Embodied carbon of Insulation =3.3*1.05(ICE) =3.47tCO2

Distance from Condell Ltd, Sutton 261km

The embodied carbon being cradle to site, this means the distance of transport to site is already factored in the embodied carbon (ICE).

Damp proof membrane (DPM)

The thickness of this does not vary and so the conversion is done based on the area of the membrane required for the floor area under consideration.

Mass per area of DPM =0.0009tonnes/m2 (CCC)

Mass of DPM =Floor area*Mass per area

= 20*30*0.0009 =0.54 tonnes

Considering 10% waste =0.594 tonnes.

Embodied carbon of DPM=0.594*4.20 (CCC) =2.49tCO2

Distance from John Newton & Co. London 250km

Transportation of materials and waste

The carbon footprint of transportation of materials and waste is done by the use of the conversion unit which gives the tCO2/ t,km.

Screed by road of 12.4km 72.6*12.4*0.000132(CCC) =0.12tCO2

DPM by train 250km 0.594*250*0.000021(CCC) =0.0031tCO2

Wastes

Considering all the 10% wastes in each material a total 21.35tonnes of wastes will need to be taken to a landfill site in Swansea a distance of 64km.

Plant emissions

Assume construction goes on for a month in a small site, Carbon footprint will be 2tCO2 (CCC)

Personnel travel

Small Site is expected to have emissions of 0.355tCO2/week (CCC) and for a month 1.42tCO2.

Total Footprint for the concrete floor=15.25+12.36+3.47+2.49+0.12+0.0031+0.26+0.18+2+1.42

=37.55tCO2

Figure 1: Percentage contribution of major impacts in the CO2 footprint for the concrete floor

## WOODEN FLOOR

The wooden floor is assumed to be such that 3 underlying beams run through the floor and the layers of wood lay on it. The components are:

3 * Rectangular beams of general timber of dimension 130mm by 50mm through 20m.

Bottom plywood layer (10mm)

Middle sawn hardwood layer (50mm)

Top hardboard layer (10mm)

The carbon footprint of each material is calculated thus:

Underlying rectangular beams

Volume of each beam=0.13*0.05*20=0.13m3

For 3 beams=3*0.13= 0.39m3

Density of general timber =0.5tonnes/m3 (CCC)

Mass of beams =0.39*0.5=0.195tonnes

Considering 10% waste=0.21tonnes

Embodied carbon of beams =0.21*0.46(Mass of material*embodied tCO2/t of material (CCC))

Distance from Bristol city timber 69km

Bottom layer plywood

Volume of plywood =Floor Area*thickness of plywood

=20*30*0.01 =6m3

Density of plywood =540kg/m3 (ICE)

Mass of plywood =6*540=3240kg =3.24tonnes

Considering 10% waste =3.564tonnes

Embodied carbon of plywood =3.56*0.81(ICE) =2.89tCO2

Distance from Cosier homes, Barry 19km

Middle sawn hardwood layer

Volume of sawn hardwood =Floor Area*thickness of sawn hardwood

=20*30*0.05=30m3

Density of sawn hardwood=0.6tonnes/m3 (CCC)

Mass of sawn hardwood =30*0.6=18tonnes

Considering 10% waste =19.8tonnes

Embodied carbon of sawn hardwood =19.8*0.47(CCC) =9.31tCO2

Distance from Cosier homes, Barry 19km

Top hardboard layer

Volume of hardboard =Floor Area*thickness of hardboard

=20*30*0.01 =6m3

Density of hardboard =880kg/m3 (ICE)

Mass of hardboard =6*880=5280kg =5.28tonnes

Considering 10% waste =5.81tonnes

Embodied carbon of hardboard =5.81*0.86(ICE) =5.0t CO2

Distance from DÃÂ©core Tiles and floors, Watford 246km

Assumption made here is that the thickness of the adhesives between each layer will be 0.1mm.

=20*30*0.0001 =0.06m3

For 2 layers will be =0.12m3

Considering 10% waste =0.297tonnes

Embodied carbon of adhesive =0.297*5.91(ICE) =1.76t CO2

Distance from Matrix Composite material company Ltd Bristol 73km

Transportation of materials and waste

The carbon footprint of transportation of materials and waste is done by the use of the conversion unit which gives the tCO2/ t,km.

Sawn hardwood by road 19km 19.8*19*0.000132=0.05tCO2

Hardboard by train 246km 5.81*246*0.000021(CCC) =0.03t CO2

Wastes

Considering all the 10% wastes in each material a total 2.88tonnes of wastes will need to be taken to a landfill site in Swansea a distance of 64km.

Plant emissions

Assume construction goes on for a month in a small site, Carbon footprint will be 2tCO2 (CCC)

Personnel travel

Small Site is expected to have emissions of 0.355tCO2/week (CCC) and for a month 1.42tCO2.

Total Footprint for the wooden floor

=0.10+2.89+9.31+5.0+1.76+0.0089+0.05+0.03+0.0029+0.02+2+1.42 =22.59tCO2

Figure 2: Percentage contribution of major impacts in the CO2 footprint for the wooden floor.

## DISCUSSION AND CONCLUSION

From the above analysis, it is clear and evident the amount of extra CO2 that would be given to the atmosphere for the same floor area but constructed with different materials. Production of cement is one of the world acclaimed huge emitters of CO2 with approximately 829 million metric tonnes of CO2 in 2000 which represents about 3.4% of global CO2 (Hanle, 2004). This evidently made the foot print of the cement based floor to be a lot greater than that of the wooden floor.

If the several mitigations that are being put in place to reduce the effects of climate change and global warming, analysis such as this need to be made paramount to be able to choose project with the lowest carbon footprint as possible but not compromising quality. It will be uneconomical to choose a project with a much lower carbon footprint with a short life time which will require a replacement in a short period. Moreover if the footprint of the new plant will be factored in, the overall footprint may become larger in the longrun so in choosing projects with lower carbon footprint the quality and lifetime of the project must be similar.

Figure 3 below gives a bar chart representating the comparison between each of the type of floors and the dominant impact being the footprint of materials where that of concrete(cement based) clearly supercedes that of the wooden floor.

Tonnes of CO2

Figure 3: comparison of the tCO2 for the major impacts for both concrete and wooden floors.