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Sustainability of Building Materials
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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.
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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.
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