Wood Rates: How Wood Products Stack Up in Green Building Systems

Green building rating systems credit wood, but do not recognize its full potential as a sustainable building material.
This course is no longer active
[ Page 6 of 8 ]  previous page Page 1 Page 2 Page 3 Page 4 Page 5 Page 6 Page 7 Page 8 next page
Sponsored by reThink Wood

Life Cycle Analysis: Getting to a Material's Real Green Quotient

LCA is an objective methodology of comparing materials or even entire structures over the course of their lifetime from resource extraction through manufacturing, distribution, use and end-of-life disposal. Although ISO 14040 provides a recognized LCA methodology, according to the study, the life cycle benefits of wood are not widely considered in the rating systems: only six of the 18 systems surveyed recognized wood's life cycle benefits, among them, Green Globes in North America. LEED currently has LCA as a pilot credit, with a decision as to whether it will be fully incorporated expected in 2011.

"The primary environmental benefit of wood, its low carbon footprint, is under-recognized, particularly in North American rating systems," says Goodland. "Yet considerations of life cycle analysis and the embodied energy of materials are critical considerations in the design of an environmentally responsible building."

It can also be said that at this time calculating life cycle impacts is complex and time consuming, the outputs hold little value to clients given the lack of inclusion in green building policies or in rating systems. Currently, according to the report, "only a few of the rating systems quantitatively and holistically address life cycle impacts of materials and of those, there is sometimes little follow-through from the calculation to the building project itself."

That said, use of LCA is on the rise in evaluating the environmental impacts of building materials such as wood, steel and concrete. Substantial work is underway to develop robust LCA data, principally by the University College London, the Consortium for Research on Renewable Industrial Materials (CORRIM), and the Athena Sustainable Materials Institute. To date, studies overwhelming confirm that wood buildings produce less air and water pollution, require less energy across their life cycle, and generate less CO2 emissions than alternative materials. Landmark research by CORRIM found wood to outperform alternative materials in studies using LCA to compare homes framed with wood and steel in Minneapolis and homes framed with wood and concrete in Atlanta. Research indicates that homes framed in steel and concrete required 16 to 17 percent more energy respectively (from extraction through maintenance) than the wood-frame homes. The global warming footprint of the steel-frame house was also 26 per cent higher and the concrete-frame house 31 percent higher than the homes framed in wood.

Salvaging a Casualty of Global Warming

Architects for the Richmond Olympic Oval have gone the distance for salvaged wood. Millions of acres of forest land have been wiped out by the mountain pine beetle. The tiny insects lay their eggs under the bark. The beetles introduce a bluestain fungus into the sapwood that prevents the tree from repelling and killing the attacking beetles with tree pitch flow. The fungus also blocks water and nutrient translocation within the tree. Because of this infestation, trees which normally capture carbon and release oxygen are now dying and releasing carbon. The beetle attacks and kills lodgepole, ponderosa, sugar and western white pines and is found in a range from the (needs spaces btw the words) Pacific Coast to South Dakota and from northern British Columbia into northwestern Mexico.

The situation is particularly acute in British Columbia. It is estimated that almost one quarter of the province's forest land has been affected to some degree by the current outbreak. Normally, cold temperatures, forest fires and natural predators keep populations in check. However, an abundance of mature lodgepole pine, combined with recent mild winters and uncharacteristically hot, dry summers, have led to an unprecedented infestation.

A silver lining in this story is that designers are beginning to specify wood that has been affected by the pine beetle. Not only does that make use of resources of dead timber, if incorporated into buildings, wood salvaged from pine beetle infested forests will continue to store carbon and delay the release of carbon dioxide into the atmosphere.

The entire "wood wave" roof on the Richmond Olympic Oval is from Spruce-Pine-Fir (SPF) dimension lumber, including mountain pine beetle affected pine stock. "Only some percentage of the entire stock is pine beetle affected," says Cannon's Johnston, explaining that when a forest products company conducts emergency harvests as a result of the infestation, it still mixes the affected pine wood with regular wood. "This is because both sources are virtually identical in structural performance and appearance, and identical to work with."

"Such an environmental emergency is typically not recognized in the sustainably harvested wood certification credits." Our "wood wave" panels are an example of innovation in sustainability rather than evidence of sustainably harvested timber," says Johnston. "In our opinion, the designers should be rewarded with credits in addition to sustainably harvested wood when demonstrating this kind of local environmental awareness and responsiveness."

Because of its low toxicity, low embodied energy and carbon sequestering properties, the wood makes a significant environmental contribution. Experts peg the total potential carbon benefit of the Oval over its anticipated lifespan is 8,800 metric tons, or the equivalent of taking 1,600 cars off the road.

Richmond Olympic Oval's roof makes use of salvaged wood.

Photo: www.naturallywood.com

 

[ Page 6 of 8 ]  previous page Page 1 Page 2 Page 3 Page 4 Page 5 Page 6 Page 7 Page 8 next page
Originally published in Architectural Record
Originally published in December 2012

Notice

Academies