guineetim: VIDEO: A New Approach to Building Greener Cities

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Indoor environmental quality upgrades, such as "living walls" and increased access to natural sunlight, combine with energy efficiency improvements to create what NRDC calls "high performance spaces." Photo: Matt Cohen/Natural Resources Defense Council

When you hear about green building, it's usually in the context of new construction. But in most cases, the biggest energy-suckers are actually structures that already exist and aren't going anywhere anytime soon.

According to research conducted by the Natural Resources Defense Council, the built environment accounts for around 40 percent of all energy consumed in the United States. In dense metropolitan areas like New York City, that figure approaches 80 percent.

Last year, the NRDC promised to help reduce the energy impact of the urban built environment through their ambitious High Performance Tenant Demonstration Project, unveiled at the Clinton Global Initiative in September 2011. Through the project, NRDC representatives collaborate with commercial tenants to incorporate energy efficiency and indoor environmental quality measures into the layout, design and construction of their spaces.

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So, how does the project work? NRDC representatives will work with eight to 10 commercial tenants who are moving into a new space and help them to incorporate energy efficiency into their normal design processes. After compiling an energy usage model and a value analysis detailing monetary savings over the lease term, the organization and participating tenants settle on five to 10 implementable energy measures to improve efficiency.

Suggested changes include energy efficiency improvements like HVAC upgrades, lighting and plug load reduction, along with indoor environmental quality measures, such as air quality improvements and increased access to natural sunlight.

The NRDC estimates that tenants can see a 30 to 50 percent reduction in energy use through such changes, with an up-front cost of about $1 to $3 per square foot. Significant efficiency improvements and low up-front cost mean most tenants will see the upgrades pay for themselves in a few years and generate a return through energy savings for the remainder of the lease - something that may come as news to many commercial tenants.

"It doesn't seem like many tenants are taking that extra step. So, what we would like to do is create a road map so that other tenants can do this without us," Wendy Fok, director of the project, told Earth911.

Want to See What the Project Can Do?: Take a Look Inside Inside the Retrofitted Empire State Building

The organization hopes the project will provide a model to other tenants looking to upgrade efficiency, and encourage building owners to present efficiency upgrade opportunities to tenants at the start of their leases.

"The primary goal of our demonstration project isn't to make these eight or 10 tenant spaces a lot more energy efficient. That's great, but our real goal here is to change the way the market behaves," explains Greg Hale, director of efficiency finance for the NRDC's Center for Market Innovation (CMI).

NRDC will compile detailed case studies after working with each tenant, which will include the economics of energy upgrades, up-front cost, savings achieved and how-to guides that will allow tenants and building owners to duplicate the model without the organization's help. CMI currently has projects on the ground in Philadelphia, Cleveland and New York City, with plans to expand to additional tenant spaces in the near future.

For more information on the project and how it could slice the energy usage of your city in half, check out the video below.

Homepage Image: Empire State Building