Short cuts
A log house- environmentally friendly
In Finland, the percentage of wood used in construction is 40%, but the burden on the environment is only 5%. The corresponding percentage of concrete used in constructions is 43%, but the environmental burden can be as high as 80%. A wooden log house has been proved to be an ecological material for buildings.
The walls of a log house form a type of “carbon bank”, to which carbon dioxide is bound up during the whole life of the house. One recent research ordered by the HTT Association and completed by the SAFA architect, Matti Alasaari, compared the carbon balances of precast concrete, brick, wood and log walls. The comparisons took the manufacture, transportation, construction and the house’s required maintenance for 50 years into consideration.
The walls of an average sized detached log house store about 24 t of carbon dioxide. The emissions caused by their manufacture and construction, were only about 2.5 t, i.e., about a tenth of the amount that was bound to the walls. At the same time, the emissions of concrete or brick walls were multifold, without the walls storing any amount of carbon dioxide at all. A log is the only building material for which the CO2 balance is clearly on the positive side.
The manufacture of logs consumes very little energy - in fact, the Ikihirsi factory even produces energy as a by-product to the process, as the planed shavings that are produced during the planning process is collected and used for the production of clean renewed energy.
Wood is also a renewable resource, and more trees grow each year in Finland than are felled. If the entire surplus of timber is used for the construction of log houses, it would be sufficient for the walls of up to 70 000 average-sized houses, without the number of trees in the country from decreasing.
- Log structures are environmentally friendly.
The construction of walls causes greenhouse gas emissions. The amount of carbon bound in the wall structures has been taken into account in this amount. More carbon is bound in log and wooden wall structures than the emissions caused in their manufacture.
Sources: Alasaarela Matti, 2008 A calculation of the environmental effects of log walls with the aid of lifespan studies and Saari Arto, 2001 The Environmental declarations of buildings and building components.
