Posts Tagged ‘Preservation’

Last week, for the first time in my life, I sat on my front porch and watched the sun set over the trees at the far edge of the open lot just to the west of my house. The day before, and all the days before that, the sun set nearly an hour earlier, over the high sturdy bulk of Brunswick’s old high school.

Crunch, crunch, crunch went the mechanical dinosaurs, chomping to bits course after course of bricks, slices of glass, and cubes of granite. Built in 1937, the school was occupied for about 60 years before the town’s high-schoolers were relocated to the outskirts of town.

From the decaying rubble pile of this old building across the street, will grow, for better or worse, a new elementary school, slated to open in 2011.

On the better side, the new building will be very energy efficient. Heating and cooling will be provided by a geo-thermal system which generates energy by exploiting the differences in temperature above-ground and underground.

The roof of the new building is to be light in color. By reflecting radiation from the sun, rather than absorbing it, light roofs can significantly cut cooling costs, extend the life-span of the roof, and reduce the heat that builds up in developed areas–all of which will lower carbon emissions and help combat global warming.

Perhaps best of all, the building is centrally located in town, alleviating the need for long bus trips and commutes.

Yet it is surprisingly difficult to conclude that this new energy efficient building will result in a net gain for the environment. It is clearly true that the building will use less energy per square foot than the older buildings Brunswick’s students currently attend.

It is less clear that the new building will use less energy per student. The new building is not simply a greener version of the older ones. It provides services the older buildings did not, such as more space per student, better ventilation, room for new programs, enhanced community space, more gym space and kitchen facilities.

One might fairly ask if all these services, which use energy and therefore gobble up some of the savings provided by a more efficient building, are correlated with better educational and health outcomes.

To further complicate matters, from an environmental perspective a simple comparison of energy use in newer and older buildings is not enough. To actually help reduce global carbon emissions, a new building must first save the equivalent of all the energy used in its creation as well as the energy used to demolish and dispose of the older building it replaces.

According to architects working on historic preservation, a new efficient office building must operate for 40 years before it has saved enough energy to offset the carbon emissions generated in its construction. If an old building must be be torn down first, then the new building must operate for 65 years just to break even.

This fact gives one pause when the U.S. Department of Energy reports that the median life-span of an office building is about 73 years.

Even when the energy used in demolition and construction are factored in, it can still be tricky to evaluate the overall environmental impact of new buildings. Consider this: the Chesapeake Bay Foundation Environmental Center, built in Annapolis in 2000, uses an impressive 70% less energy than a typical office building, but may still not have resulted in a net environmental gain.

The Foundation’s old offices were in the middle of town, while the new building was sited 10 miles out. An analysis by the Environmental Working News concluded that the new center, one of the most efficient buildings ever built, may have only succeeded in offsetting emissions from the increase in employee commuting.

Of course, if you’re going to put a new building 10 miles from a town center, it’s important to make it as efficient as possible. However, if we are to succeed in reducing our global warming emissions we have to do better than holding our own and we have to do better than implementing solutions with 60+ year energy paybacks. It is not enough to simply exchange an inefficient something for a more efficient something.

The new wildly popular Cash for Clunkers bill, recently re-infused by the legislature with another two billion in taxpayer money, comes to mind. Under the terms of this bill, folks can receive a rebate of $3,500 to $4,500 for trading in “clunkers” (defined as vehicles getting less than 18 miles per gallon) for more efficient vehicles (defined as vehicles getting as little as 19 to 22 miles per gallon).

Although marketed as a means to fight global warming, the bill may do just the opposite. Simplistically, it’s better to replace an 18 mile per gallon (mpg) car with a 19 mpg car. Yet, to reduce total carbon emissions the new car has to not only have better fuel economy than the old car, but it has to pay back the energy used in manufacturing itself as well as the energy needed to dispose of the old car. At 19 mpg, a new vehicle may never break even.

The Union of Concerned Scientists concludes that in order to generate a unambiguous benefit for the environment, Cash for Clunkers rebates should only apply to folks trading in a vehicle that is at least 8 years old and getting a new vehicle that is in the top quarter of efficiency rankings for its class. Without these measures, the bill may wind up increasing global warming emissions.

To determine if a sexy new program (or building or solar array or biofuel) truly reduces global warming emissions we need to do careful scientific analyses and we need to rely on those analyses to set policy. The results are not always obvious.

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