Wood Works! with less energy.

Wood as a structural material consumes less energy than conventional materials

Construction, renovation and operation of a building consumes more of the earth's resources than any other human activity. No other sector has a greater impact on the global environment. Each year it generates millions of tonnes of greenhouse gases, toxic air emissions, water pollutants and solid wastes. It is interesting to note how wood compares with other materials in terms of its ecological impact as a building material.

A case study examining the environmental effects of wood, concrete and steel proved that wood has the lowest energy use. The study applied the ATHENA computer model, using a life-cycle analysis approach. This model is the result of a five-year research program involving a unique alliance between architects, environmentalists, economists, engineers and representatives from the steel, concrete and wood industry. The program is coordinated by Forintek Canada, and supported by the Canadian federal government.

The case study involved a 50,000 sqaure-foot, three-storey office building with a single storey of underground parking," says Catherine Lalonde, professional engineer and director of education for the Canadian Wood Council.

"Professional structural engineers were retained to develop alternative structural designs for the building using primarily wood, steel and concrete elements," she adds.

The ATHENA model analysed raw materials and energy uses as well as emissions to air, water and land for the three design options. On all aspects, the wood design consistently outperformed steel and concrete by having the least impact on the environment.

The wood design had the lowest energy use. The concrete design required 1.5 times the energy and the steel design used 1.9 times the energy of the wood building.

"In considering the above grade structure, without the concrete parking garage which is common to all three options, the energy impact of the choice of framing becomes more pronounced," Lalonde says. "The concrete option required 1.7 times more and the steel option required 2.4 times more energy than the wood option.

Lalonde says the wood building had the lowest greenhouse gas emission.

"The steel building option generated 1.45 times more greenhouse gas and the concrete building option generated 1.81 times more greenhouse gas than the wood option.

Similar results were found when looking at the air and water pollution index. The steel design produced 1.42 times as much air pollution as wood, with the concrete design producing 1.67 times as much air pollution as wood. The steel design generated 120 times more water pollution than the wood design and the concrete design generated 1.9 times more water pollution.

Lalonde says the study adds analytical weight to the claims that wood is renewable, requires less energy to manufacture, produces much less air and water pollution and helps combat the greenhouse effect.