Friday, March 12, 2010

The Greenest Building

There is a lot of chatter at the moment about green buildings, and LEED certification, and where historic preservation fits within the very real need to reduce our energy consumption.  Unfortunately too many take this valid goal as justification to scrape any “old” building off the planet and replace it with an all new, state-of-the-art design.  Sometimes that is justified but not always, and hardly ever from the standpoint of really saving energy.
When I was in school, one of the smartest things anyone ever told me was when somebody is trying to justify an action that you question, find out what their assumptions are.  In the case of energy efficiency, people who want to raze historic structures assume that the new building will “save energy.”  How they calculate that is critical.  Typically they model the two buildings side by side…the new building is better insulated, it has more efficient windows, maybe it's sited to take advantage of solar gain.  The “old” isn’t  “See, the new LEED-gold project with bamboo flooring is much more efficient.”  And it probably is.  To operate.  

What a side-by-side comparison ignores is the reality of the standing building.  It is there.  The energy to construct it has already been expended.  All the materials have been made, carted to the site and installed.  It’s demolition will require more energy to remove, to haul debris away, filling the landfill.  The other day, as is typical, somebody told me that restoring a historic building wasn’t practical because it was too expensive to abate all the hazardous materials (mostly asbestos floor tile and pipe wrap).  Instead of restoring it would be “cheaper” to raze the building, they said.  I pointed out that you still have to abate hazardous materials before you demolished, so you really weren’t saving that money.  And, of course, you aren’t.
If you consider “embodied energy” (not the energy to operate), the greenest building is ALWAYS the most efficient structure around because that energy has already been expended.  And there is a LOT of embodied energy in a typical building.  The Advisory Council on Historic Preservation (a Federal regulatory agency) calculates that the amount of embodied energy in a 50,000 square foot commercial building is 80 billion BTUs, the energy equivalent of 640,000 gallons of gasoline.  Tearing that building down, carting it to the landfill, and building a new structure of the same size, even the most efficient, green, LEED Gold with clusters  and unicorns, design will still release as much new CO2 into the atmosphere as driving a car to the moon and back.  Every day. For a month.

Back to operation, as a result of the embodied energy already in a standing building, even the most efficient new structure won't really save energy over an existing one for a long time.  Fifty years long time.  So if you REALLY want to be green and reduce operating costs too, invest in upgrading your existing building.  Improve the heating and cooling.  Insulate. Weatherstrip and caulk to reduce heat loss.  But don’t tear it down and start over.  Or at least don’t claim you are doing so to save any energy. You’re not.  Reuse is always more energy efficient than even the best recycling or the best designed new building.  It’s just a fact.
Check out this great site for more information on The Greenest Building (is the one that is already built).

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