potrero view

August 2009

How Green Will the New Library Be?

By Mary Purpura

It’s hard not to miss the library, which closed for renovations on May 17, 2008. The Potrero branch was a center of community activity, with the annual art show, children’s story times, and the warm and welcoming staff that’s worked there over the years.  Fortunately, the library’s renovation is proceeding as planned, with an expected reopening in early 2010, according to Mindy Linetsky, administrator of the Branch Library Improvement Program, a joint project of the San Francisco Public Library and the San Francisco Department of Public Works.

In addition to a host of other amenities, the reconstructed library will include green features.  However, the building will not be LEED-certified, since “the plans were drawn before San Francisco enacted its LEED ordinance requiring buildings over 5,000 square feet to be certified LEED silver,” explained Paul De Freitas, head architect for the Potrero Branch renovation. The LEED (Leadership in Energy and Environmental Design) rating system was developed by the U.S. Green Building Council, a nonprofit group of building industry leaders that promotes environmentally responsible building. Qualified buildings are given silver, gold, or platinum LEED ratings, which represent ascending levels of environmentally sound building features and energy efficiency. “The Potrero branch library has been designed on LEED principles to a high level of sustainability,” even though it won’t be officially certified, said De Freitas.

For an ecologically sound renovation, an architect needs to incorporate design elements that will reduce a new building’s energy consumption and associated carbon footprint.  As is apparent to anyone who has passed the library over the last two years, the renovation involved almost complete demolition of the building, leaving only the exterior walls intact. Because the original library was built in 1953, it had practically no insulation and its windows were single-pane. The new building will be fully insulated, with high-performance, double-pane, low-E (low emissivity) windows. Low-E windows are more efficient because heat originating from indoors is reflected back inside, thereby keeping warmth inside in the winter, and infrared radiation from the sun is reflected away, maintaining a cooler building in the summer.

They’ll be less artificial lighting in the new library, thanks to a design that maximizes the natural light entering the building. “The entire south side of the building will be floor-to-ceiling glass, and the north side is pretty much floor-to-ceiling glass, too,” said De Freitas.   “The great views you had from the back of the old library will still be there, but there will also be big windows [about 13.5 feet tall] on the second floor, expanding and extending that fabulous view,” said Linetsky. Skylights and clerestory windows opening into a central atrium will provide even more daylight.

The re-design includes a natural ventilation system, which should keep interior temperatures comfortable even on the hottest days of the year. Thermostatically controlled exhaust fans will punctuate the second floor’s high ceiling. When necessary, those fans will pull warm air up through the atrium, replacing it with cooler air from the operable windows on the south wall.

While the library won’t have solar panels or a living roof – budget constraints prohibit those more expensive options – it will feature a CCRC (Cool Roof Rating Council)-certified cool roof.  Cool roofs are made of materials that reflect the sun’s energy back from the roof surface. This keeps the building’s interior cooler on hot days, and it reduces the urban heat island effect, which forms as an area becomes more developed, replacing vegetation with asphalt and concrete. These surfaces tend to absorb, rather than reflect, the sun’s heat.  If, at some point in the future, the community decides to fund-raise to gather money for solar panels, the new roof will be suitable for installing them.  

Throughout the building, low-VOC (volatile organic compounds) products – paints, finishes, varnishes, adhesives, and sealants – will be used. Volatile organic compounds are responsible for that strong paint smell that typically lasts for days. No- and low-VOC products, on the other hand, are manufactured to release no, or minimal, VOC pollutants, and they’re nearly odor-free. As VOCs are considered detrimental to people’s health and to air quality, this is an important green feature.

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