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Period Homes Magazine



Common Sense Green Building

By Michael C. Connor

In the quest to build homes that are environmentally friendly, much attention has been given to the impact new construction has on renewable resources, and the most obvious one is wood and wood products. Who can argue with the premise that the fewer trees required to construct a house, the better off the environment will be? A whole generation of engineered-wood products has evolved in the past 50 years, and the enthusiasm in the current green-building movement for waste-stream products has lent manufacturers a free marketing campaign. Virtually every green building certifier touts these products as major contributors to earning "green points" in their certification process.

In an ironic twist, the major beneficiary of this free marketing blitz is the long-time nemesis of environmental activists, big lumber. Such corporate giants as Georgia Pacific, Boise Cascade and Louisiana Pacific, to name a few, are the major producers of engineered-lumber products. These products that resulted from early research and development by the lumber industry were originally intended to be a way that the industry could create salable building materials from the waste stream. The perfection of phenolic resins that allowed these waste-stream products to be bonded together into usable building materials was the major catalyst that brought them viability in the building-products marketplace. The green building movement is the catalyst that has allowed them to flourish in today's environmentally sensitive marketplace.

We are making building materials from waste products and saving trees, so this is a good thing, is it not? On its face, it would appear that the stars have aligned, and environmental activism and big lumber share in the environmental sweepstakes, but upon closer inspection, another perspective emerges, whereby environmentalists are duped and big lumber smiles all the way to the bank.

The big sellers in engineered lumber are oriented-strand-board panels (OSB) used for sheathing, and solid web I-joists (whose webs are made of OSB). These I-joists are structural members made to replace solid sawn- lumber joists. A recent study (February 2007) by the National Association of Home Builders and Bank of America surveyed a wide range of manufacturers to determine the life expectancy of their various products. Georgia Pacific Corporation was the source for life expectancy of OSB, and by its own estimate concedes that it is expected to have a service life of 25 to 30 years. The Engineered Wood Association, a promotional organization for engineered wood products says that "The service life of OSB is indefinite (expect 50 years or longer) if it is used and protected properly." Since this product hasn't been around long enough, no empirical evidence exists to prove or disprove these service-life estimates, or what proper protections are required. But even if these products last 40 years, should it not be alarming that structural components of homes are being built with materials that condemn these homes to such a short life? When entire floor and roof structures are made of built-up systems whose major component is likely to fail in 30 to 50 years, you can bet that the entire home with all its embodied energy will be razed, because the collateral damage of structural failure would be overwhelming.

It is interesting to note that in the same NAHB study, the same question as to service life for roof and floor trusses was answered by the Engineered Wood Association, whose members include all the big lumber players mentioned above, and the answer is a curious and evasive "lifetime." The warranty information for these products also references "lifetime" as the warranted term. Whose lifetime are we talking about? Could it be that this is a remarkably safe warranty exclusion, given that when a major structural element (the I-joist) fails, the "lifetime" of the house is self-defined? Incidentally, the warranty for these products is a "limited lifetime" warranty, meaning it is only warranted to the original owner. Given that the average ownership cycle is about 12 years, it appears that not many warranty claims would be honored anyway, making warranty discussions moot for the most part.

A more important discussion might be the wisdom of lending institutions financing homes to the second or third owners with mortgage terms that might exceed the expected lifespan of the home. It is a common misunderstanding today that using engineered-wood products in place of dimensional lumber is a quid pro quo swap. In reality, the disparity in life-cycle expectancy between the two products is being ignored, with the inevitable fallout being pushed to the next generation, whose expectation of being the beneficiaries of their parents' greener building policy will have collapsed along with the short-term structural building components upon which that policy was built. While the actual service life of an I-joist/rafter can be debated until failures are reported, it would be fair to say that if Thomas Jefferson's Monticello had been built using I-joists and I-rafters, visitors today would be viewing an archeological dig, not a museum.

Environmentalists and the lumber industry agree that savings in actual lumber usage in building a home with engineered lumber may be as much as one-third. Given that the average 2,500-sq.ft. home built today of solid sawn lumber uses the equivalent of about 20 trees, building with engineered lumber will save about six of those trees, and use 14. However, empirical evidence shows that a house built of solid sawn lumber will last hundreds of years. At the end of 40 years, when the engineered-lumber house is being rebuilt with another 14 trees, the solid-lumber house continues on, using no new trees. At 80 years, another 14 trees are used up in the "environmentally friendly" home, while the solid-lumber home continues on. At 120 years the score is: "environmentally friendly" home, 56 trees; solid-sawn-lumber home, 20 trees. This is to say nothing of the embodied energy lost each time the home is rebuilt. It has been estimated that it takes the equivalent of 10 gallons of gasoline per square foot in embodied energy to construct a house. This means that we can add another wasted 100,000 gallons of gasoline lost in the same time span of 120 years.

Admittedly, homes don't last for 120 years and more without maintenance, but again we know from experience that the maintenance required is normal and routine. More important is the motivation that promotes the kind of stewardship that is required to keep a home on the landscape. That motivation is first generated by the financial incentive to protect our investment. But history teaches us that a more powerful motivator is beauty. A beautiful home is likely to inspire enhanced stewardship, while an unattractive home will not. And how do we quantify beauty in a home? Beauty being in the eye of the beholder, we would have to survey a large sample of beholders to at least arrive at a consensus. Or, again we can turn to history. The ability of a home to sustain itself on the landscape has much to do with its inherent architectural beauty, and homes rooted in Classical forms have proven their aesthetic durability over many centuries, and therefore can rightfully claim their prominent position in aesthetic considerations.

The aesthetic character of a home that contributes so powerfully to its sustainability is often ignored in "green home" analyses, and in fact some of the mechanics of green technology (solar collectors, photovoltaics, shading devices, etc.) can adversely affect an otherwise pleasant aesthetic presentation. A recent article in Preservation magazine states that the greenest building is the one that already exists. In the equation for designing a green building strategy, it is imperative to consider the durability of the home, as overcoming the lost embodied energy in rebuilding a home is not nearly accomplished by all the green technology put together in a new home.

The green building movement is entirely laudable in its effort to bring environmental harmony to the human endeavor of creating shelter, as that endeavor is ongoing and of sizable environmental impact. However, the movement should be cautious and take the time to examine its own strategies and apply common sense so that methods that appear attractive, but may in fact be deleterious to the intended goal, are not followed. History is a powerful teacher, and the time-honored tradition of building homes with durability as defined by their structural elements and architectural aesthetics should not be ignored, and it should be an essential component of any "green building" strategy.  


Michael C. Connor is the founder of Connor Homes, a homebuilder based in Middlebury, VT.

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