Carbon emissions during construction and the manufacturing of materials for it are not taken into account when comparing the environmental impacts of buildings.
Improving the energy efficiency of buildings means decreasing their energy use and thus the carbon emissions. However, it also leads to thicker walls and more insulation. Manufacturing these requires both energy and natural resources.
”The choice of material for making walls and insulation should be taken into account. We ought to assess a building’s use of natural resources and energy and its carbon emissions during its whole life cycle,” says Mr. Mikko Viljakainen, Director of the Business Sectors and Competitiveness Group at the Finnish Forest Industries Federation.
Viljakainen has compared the environmental impact of making and using different kinds of exterior walls, joists, interior walls, exterior cladding and insulation materials. He defines the environmental impact as the effect on the consumption of natural resources and energy.
The conclusion is simple: construction solutions that utilise concrete, steel and brick use more natural resources and energy than equivalent solutions using timber. In addition, timber solutions function as carbon storages and can be recycled into energy, while recycling concrete and steel only consumes energy.
Environmental impact of
construction is on the increase
Currently, construction and the manufacturing of construction materials account for roughly five percent of Finland’s annual energy consumption and carbon dioxide emissions.
According to Viljakainen, new requirements for energy efficiency, coming into force in 2010 in Finland, will lead to increasing environmental impacts. The use of natural resources in construction and the manufacturing of construction materials will increase by ten percent; the use of energy will increase by 20–25 percent and carbon dioxide emissions by about 20 percent.
The biggest share of this, or 60 percent, is due to concrete construction. The second most important factor is steel. A concrete interior wall takes almost seven times the amount of natural resources that a timber wall does.
For timber solutions, the impact of energy efficiency requirements is the opposite.“Thanks to thicker walls due to energy efficiency requirements, the carbon stored in timber exterior walls increases by 15 percent. In addition to this, the energy available in recycling them after use increases by 25 percent.”
“The natural resources are becoming scarcer. We must consider the best ways of using them. Instead of using a piece of steel as a joist in an interior wall for 70 years, it could be used ad re-used in seven cars in the same time,” Viljakainen compares.
Use of wood in construction should increase
As to Viljakainen, the conclusion is clear: new manufacturing methods must be developed and the focus moved to materials that cause the least emissions. In other words, wood must always be used when it is applicable.
A timber wall functions as a carbon storage. Even though gypsum sheets are often used to clad a timber interior wall, the carbon stored in the timber also compensates for the carbon produced in manufacturing the sheets. Also, a timber wall generates more energy than is used in making it if it is recycled after use into energy production.
The market share of timber in all building frame structures in Finland is 40 percent. Nevertheless, wood accounts for only five percent of the overall natural resource and energy consumption in construction and the manufacturing of construction materials. Concrete has a market share of 43 percent, yet it causes around 80 percent of the said environmental impact.
Currently, there is no driver to take the carbon emissions, natural resource use or energy consumption in construction into account. Even trade in emissions of greenhouse gases has no effect in this case.
Ten hours’ forest growth enough for a year's houses
Half of the natural resources used by humankind are used in construction. It generates 40 percent of all waste. These are ample reasons for studying the environmental impact of construction.
There is also ample timber in Finland. The timber needed for all new residential buildings constructed in Finland in a year grows in our forests in the space of ten hours.
"We build six dwellings per one thousand people annually, while the Europeans average is 2.4. At that rate, the annual increase in Finland’s forest resources would be enough for dwellings for a thousand million people,” says Viljakainen.
For all the benefits of using wood, why is the situation as described? Because "our competitors are better lobbyists," says Viljakainen.
"Steel and concrete only stand to lose if the current situation changes,” is Viljakainen’s opinion on why carbon emissions from construction and the manufacturing of construction materials are not taken into account in the semi-official major forest state of the EU.
By Krista Kimmo
 Report on the environmental impact of construction and the manufacture of building materials
 Finnish wooden houses use less energy than stone houses
Wood selected for a nine-storey residential building in the UK
 Development of sawn softwood timber consumption 1994-2004 24,32 Kb
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