Energy Efficiency of Wood
Sustainability of Building Materials | | Wood | Steel | Concrete |
|
Total Energy Use
|
Lowest
|
140% more
|
70% more
|
|
Greenhouse Gases
|
Lowest
|
45% more
|
81% more
|
|
Air Pollution
|
Lowest
|
42% more
|
67% more
|
|
Water Pollution
|
Lowest
|
1900% more
|
90% more
|
|
Solid Waste
|
Lowest
|
36% more
|
96% more
|
|
Ecological Resource Use
|
Lowest
|
16% more
| 97% more
|
Source: The Athena Sustainable Materials Incentive
Wood surpasses steel and concrete in energy efficiency through its qualities of:
- Thermal performance
- Heat conductivity
- Building codes
- Insulation
Thermal Performance
The heating and cooling of homes accounts for 50% of all utility costs (gas, oil, hydro-electric) and about 15% of all energy used in North America. With rising energy costs and rolling blackouts across the country, energy efficiency is a critical factor in buying or building a new home. The energy demand difference between a poorly constructed and a well constructed, well insulated home can amount to several thousand dollars a year.
Wood's Heat Conductivity
Wood is 400-times less heat conductive than steel and 8.5 times less conductive than concrete, so homes built with wood framing take less energy to heat and cool.
Steel's Heat Conductivity
Like the fins on a radiator, sheet metal studs transfer large amounts of heat to the outside air during winter. They also transfer cold inside during summer. The movement of cold into a house through the framing is called thermal bridging . Thermal bridging increases energy consumption. To prevent this, steel framing requires extra insulation on the outside sheathing which can add significantly to building costs. The heat loss through steel framing can also result in lower temperatures where the steel contacts interior walls resulting in ghosting (paint discoloration).
Building Codes
Wood construction can meet the energy codes of all climates. In extreme climates like Alaska and the Canadian Arctic, the adoption of double wood-frame wall systems keeps homeowners warm when temperatures drop in winter to -40ºF. New energy code requirements in several European countries have prompted a switch from traditional masonry construction to wood.
Insulation
Wood is energy efficient not only because it's a good insulator, but its versatility makes it easy to adjust the width of a wall to accommodate extra insulation where necessary. Additionally, oriented strand board (OSB) or plywood wall sheathing, typically used under a home's exterior finish, offers additional insulation and provides rigidity and security to a home. The insulated cavities in wood-frame construction, in combination with the superior insulating capability of wood framing means that wood can meet the most demanding energy codes with less cost.
Biodiversity Forests are home to roughly two thirds of the 140,000 species of plants, animals and invertebrates estimated to occur in Canada.
Forestry companies achieve biodiversity through specific reforestation:
- Using native species
- Following the classification system
- Avoiding genetic engineered products
- Applying the latest science
Native Species
In order to retain the natural biodiversity of each forest region in Canada, harvested areas are regenerated with native tree species. More than 30 different species of trees are planted in the various regions to ensure that reforested areas are as diverse as the forests that were harvested.
Classification System
B.C. has developed a classification system that allows resource professionals to base decisions on detailed information about climate, soils and characteristic vegetation in each of 14 unique ecosystem zones. In the past, it was not uncommon to log Sitka spruce or hemlock and replant the harvest area with Douglas-fir because of its higher commercial value.
Genetic Engineering
B.C. does not use any genetically modified or genetically engineered trees. Its seed and seedlings come from natural wild stands or seed orchards that promote desirable traits from natural stands.
Applying the Latest Science
Where forest companies were once encouraged to clean up harvest areas, forest professionals know that debris such as the stumps, branches and fallen trees left on the forest floor after harvesting are critical to manage biodiversity. They provide habitat for plants, animals and insects, and a source of nutrients for soil development.
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