3.7 Problems with Material Use – Embodied Energy

 

 

3.7 Problems with Material Use – Embodied Energy

The production of all of the materials mentioned above will involve processes that use energy. As highlighted in the previous chapter, this energy will in most cases comes from the burning of fossil fuels which have their associated environmental impacts. The term which refers to all the energy required to extract and process the raw materials, manufacture the product and transport it between each stage of production is known as the Embodied Energy.

Examples of materials and their level of embodied energy are:

High: concrete ,metals , asphalt , glass and petroleum based thermoplastics

Low : wood , fibers , re-used , re-cycled, by-products of other processes

Table 3.7.1 Embodied Energy of Various Construction Materials:

Material

Density kg/m3

Embodied Energy

Low value GJ/m3

Embodied Energy

High value GJ/m3

Natural aggregates

1500

0.05

0.93

Cement

1500

6.5

11.7

Bricks

~1700

1.7

16

Timber (prepared softwood)

~500

0.26

3.6

Glass

2600

34

81

Steel (sections)

7800

190

460

Plaster

~1200

1.3

8.0

Source: MIT Opencourseware [see reference 3]

Table 3.7.1 sourced from MIT opencourseware under a Creative Commons Attribution-NonCommercial-ShareAlike 3.0 United States License
http://dspace.mit.edu/bitstream/handle/1721.1/39134/1-964Fall-2004/NR/rdonlyres/Civil-and-Environmental-Engineering/1-964Fall-2004/7304E211-2A38-4420-90C5-9669E185203F/0/lec1_introduction_jao.pdf


Materials with the lowest embodied energy intensities, such as concrete, bricks and timber, are usually consumed in large quantities. Materials with high energy content such as stainless steel are often used in much smaller amounts.

Another way of looking at embodied energy is considering the equivalent carbon dioxide released in the burning of fossil fuels to create the materials. The chart below shows this for various materials. Note the change in embodied energy units from GJ/m3 to GJ per tonne.


Table 3.7.2 Embodied energy and CO2

Materials

Embodied

energy

(GJ/t)

Embodied

CO2 (kg/ton)

In – situ concrete

0.84

119

common bricks

5.8

490

timber

13

1644

structural steel

25.5

2030

plasterboard

27

180

aluminium

200

29200

Source: MIT Opencourseware [see reference 3]

Table 3.7.2 sourced from MIT opencourseware under a Creative Commons Attribution-NonCommercial-ShareAlike 3.0 United States License
http://dspace.mit.edu/bitstream/handle/1721.1/39134/1-964Fall-2004/NR/rdonlyres/Civil-and-Environmental-Engineering/1-964Fall-2004/7304E211-2A38-4420-90C5-9669E185203F/0/lec1_introduction_jao.pdf

 

 

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