Last week, I offered up a number of statistics generally comparing wood to other building materials. This week, here are some interesting stats specifically from various Life Cycle Analysis (LCA) research for wood as a building material. Most of this has to do with structural wood, but I think it can be useful showing the durability and energy efficiency of our industry.
- This LCA by Science Daily found that using wood flooring instead of concrete slab flooring reduced the carbon footprint by approximately 3.5 tons of carbon dioxide for every ton of wood used.
- The same LCA by Science Daily compared replacing steel floor joists with engineered wood joists-and found a reduction of the carbon footprint by almost 10 tons of carbon dioxide for every ton of wood used.
- Two buildings in Sweden and Finland constructed with wood frames were compared with functionally equivalent buildings constructed with concrete frames. "Carbon accounting includes emissions due to fossil fuel use in the production of building materials, the replacement of fossil fuels by biomass residues from logging, wood processing, construction and demolition, carbon stock changes in forests and buildings, and cement process reactions. The results show that wood-framed construction requires less energy, and emits less CO2 to the atmosphere, than concrete-framed construction. The lifecycle emission difference between the wood- and concrete-framed buildings ranged from 30 to 133 kg C per m2 of floor area. Hence, a net reduction of CO2 emission can be obtained by increasing the proportion of wood-based building materials, relative to concrete materials."
- Consortium for Research on Renewable Industrial Materials used typical building designs to construct hypothetical homes, then compare the environmental benefits of wood-framed versus steel-framed houses in a cold climate (Minneapolis, MN) and wood versus concrete in a warm, humid climate (Atlanta, GA). The LCA concluded that construction of the wood-frame home used 17% less energy than the matching steel-frame home and 16% less energy than the matching concrete-frame home. (The energy consumption measured included not just electricity, but also diesel and fuel oil to extract and haul materials, natural gas to generate steam in lumber mills, and electricity for steel mills.) Furthermore, the global warming potential of the wood-frame home was 26% lower than the steel-frame home and 31% lower than for the concrete-frame home.
- Another study conducted by the Canadian Wood Council compared the life cycle impacts of three 2,400 square foot homes designed primarily in wood, steel and concrete over the first 20 years of their lives. Relative to wood, the steel and concrete homes were predicted to require 26 percent and 57 percent more energy (from extraction through maintenance) as well as emit 34 percent and 81 percent more greenhouse gases.
Next week, we'll start to explore another way wood is green-the fact that you can use it over and over and over again.