When it comes to green building, shiny new designs always seem to get the most attention. But to realize the full potential of the sustainable building movement, we must look beyond new construction and focus more on what is happening to existing, everyday buildings made of brick and brownstone, shingle and slate. Ultimately, our treatment of these older, often historic structures will have far more impact on our total carbon footprint than will new construction.
Scot Horst of the U.S. Green Building Council has pointed out that the energy we could save by improving the performance of our existing building stock by just one percent would equal the savings that would be achieved if all of the new buildings constructed in the United States during a given year were "netzero."
At the National Trust for Historic Preservation, we believe that energy efficiency in our older buildings can be improved by more than one percent - far more. By tightening exterior envelopes, restoring original passive design features, and adding modern improvements, we believe tolder structures can meet - or exceed - the highest standards for energy performance and sustainable design. Even more, we think it is possible to do this at reasonable cost and without compromising historic character and integrity.
The Emerson School Project
We plan to demonstrate how to improve energy efficiency in older buildings through work on a property that was recently donated to us in Denver, Colorado. The Emerson School is a two-story masonry structure built in 1885. A one-story "cottage school" for kindergartners and first graders was added in 1917. The total building area is 20,000 square feet.
In its design, form the Emerson School is similar to thousands of other historic schools and institutional buildings found across the nation: timber-frame construction, thick masonry walls, large windows, and high ceilings. Also typical is the condition of the building: functional, but in need of a little work.
Actually, more than a little. We're spending $2.1 million in hard building costs to convert the Emerson School to a center for historic preservation groups and other nonprofits. This work includes installing a geothermal HVAC system, repairing original wood windows, replacing inefficient light fixtures and opening up the interior to restore passive ventilation and natural lighting schemes that were lost over time.
As a result of these improvements, energy models suggest that energy consumption at the Emerson School should be more than 40 percent below the ASHRAE 90.1 baseline. Ultimately, we'd like to reduce energy use even more. At an Eco-Charrette last year we were inspired by the vision of the Living Building Challenge and agreed to a target of "netzero" resource consumption at the Emerson School by 2030. (More on how we'll get there in a future article.)
To LEED or Not to LEED?
At the Eco-Charette, we also discussed whether we should seek LEED certification for the rehabilitation of the Emerson School. The subject of LEED certification continues to arouse debate in the historic preservation community. Early versions of the LEED rating system barely acknowledged the environmental benefits of retaining and re-using existing structures. Historic preservation advocates and architects (including former National Trust staff member Barbara Campagna) have pushed, with some success for changes that help put historic buildings on a more equal footing with new structures in the LEED rating system. Nonetheless, of the nearly 9,000 LEED-certified projects across the nation, we have been able to document fewer than 100 that involve designated historic buildings.
Earlier this year, we posted a blog on our website, www.PreservationNation.org , asking readers to weigh in on whether we should go for LEED at Emerson, or not. The comments we received on the blogpost and on our facebook page were informative and thoughtful. Several people sympathized with our dilemma and shared stories of their own experience. Of those who took a position, opinion was fairly evenly divided: