Want to build green? The best way isn’t to build at all, but to retrofit an existing building, says architect and green building expert Sandra Mendler.
“In general, it’s always better to reuse a building” than to tear it down and build a new one, Mendler said.
The reason? Over a 30-year span, 20 percent of a building’s energy consumption is embodied in the building’s physical structure itself, she said.
The San Francisco architect was speaking Friday as a member of a panel on Green Building and Development at the UC Berkeley Energy Symposium.
The point she made reinforces a theme in the draft Downtown Area Plan prepared by a City Council-appointed citizens’ panel.
During deliberations over proposed rules on new downtown construction, preservationists and environmentalists found common ground in urging adaptive reuse of existing buildings whenever possible instead of a more radical approach favored by a minority who sought a more aggressive demolition policy.
The architect said that while older buildings are often less energy-efficient, retrofits can generally achieve the same levels of efficiency as new construction.
Mendler was joined on the panel by Lawrence Berkeley National Lab Senior Scientists Steve Selkowitz and Charles Huizenga, an adjunct professor of architecture at the university, and Gail Brager, associate director of the university’s Center for the Built Environment.
In an era where terms like “global warming” and “greenhouse gases” have entered everyday conversations, buildings are looming ever larger as source of planet-warming emissions and as major targets for energy conservation.
“Buildings account for a third of energy consumption and carbon emissions,” Brager said.
Selkowitz said 40 percent of the emissions of carbon dixoide—the leading greenhouse gas—stem from buildings, which also consume 71 percent of electricity used and 54 percent of natural gas consumption.
As head of LBNL’s Building Technologies Department, Selkowitz said his goal is to create buildings that consume only as much energy as they can create, or zero energy buildings.
Selkowitz and his team applied their skills to the new New York Times headquarters building, a billion dollar tower enclosing 1.5 million square feet.
Mendler said buildings generate 20 billion tons of carbon dioxide, demanding an integrated approach to design that captures not easily controlled “low-hanging fruit” but captures even greater savings through integrated old and new technologies.
An acknowledged leader in the sustainable architecture movement, Mendler sits on the board of the U.S. Green Building Council and is past president of the American Institute of Architects’ Committee on the Environment.
Just last week she moved from the San Francisco office of HOK to a new position as a principal of the new San Francisco office of Seattle-based Mithun Architecture.
Huizenga, who also conducts research at the Center for the Built Environment, is the founder of Adura Technology, which makes wireless lighting controllers for commercial buildings which, he said, can result in substantial energy savings in existing structures.
Starting with experiments at the Marchant Building, Huizenga found that by allowing officer workers to control the lights in their own work areas, electrical use dropped 60 percent compared to the typical building, where large area lights are controlled by switches often placed in locked utility closets.
The technology has since been applied to two campus libraries, Moffit and Doe, where lights had been left on around the clock. The net energy savings works out to 170 megawatt hours a year.
Another architectural innovation can result in significant savings on new buildings, ostensibly designed for maximum energy efficiency, Mendler said.
Called commissioning, the process brings in experts to see how effectively the designs have been implemented in practice. A study conducted of “green buildings” revealed that their actual performance was 30 to 40 percent worse than planned and improved significantly after the work of commissioning engineers.
Mandler said that 90 percent of a building’s embodied energy derives from five material choices: framing (steel, concrete or wood), enclosure systems (glass, masonry or metal), flooring, roofing and partitions.
As an example, she said, aluminum takes ten times the energy to produce as steel.
One resource for builders who want to calculate just how green their projects are can be found on the website buildcarbonneutral.org, Mendler said.