Building in Use - Environmental aspects

CO₂-balance of the building

The table below shows the environmental impact of 1 kWh of heating energy (depending on the fuel/energy used) (go to GBC - the green building challenge handbook):

	Funct. Unit	Global Warming Potential	Acidification potential	Primary Energy Input
Unit		kg CO₂ equ./kWh	kg SO₂ equ./kWh	kWh/kWh
Oil	kWh	0,313	0,719	1,317
Natural gas	kWh	0,263	0,320	1,319
Electricity	kWh	0,576	3,957	3,770
Wood chips	kWh	0,014	0,540	1,369

The above data when used with heating energy consumption values will allow a simple calculation of the CO₂ balance of a building over a one year period. For example, if the heating energy consumption is 50 kWh/m²a and the house has an area of 150 m² and a natural gas heating system, the total CO₂ output (GWP) is 0.263 x 50 x 150 = 1.972,5 kg CO₂ equivalent.

Compared to the CO₂ produced by a building’s heating system, the CO₂ emissions caused by the production process of bricks and clay blocks are very low. The GBC-study of the clay brick industry in Germany, Austria and Switzerland (see GBC - the green building challenge handbook –> “Building materials”) shows a GWP value of 0.194 kg CO₂ equivalent per kilogram of clay bricks. A 150 m² family house will involve on average the use of 40 tons of clay bricks or blocks that will generate 7.760 kg of CO₂ during their manufacture. In other words, the CO₂ output resulting from four years of heating exceeds the CO₂ caused by the manufacture of the bricks.

Normally, mass brickwork has an average life of at least 90 years. If the CO₂ output caused by the brick manufacture is divided over 90 years, the average annual CO₂ load is only 86 kg CO₂, or 4,4% of the CO₂ produced by the heating system.

»The Clay Life Cycle
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