Sustainability at the Library–What are the facts?

The Cedar Rapids Public Library Board of Trustees has mandated that the public library will be built to LEED Gold Certification standards as established by the United States Green Building Council (USGBC).  The library design team consisting of the library officials, OPN Architects, Design Engineers, Ament Engineering and Ryan Companies have set this as a minimum standard and hope to achieve the level of Platinum Certification in the LEED Rating System.

The Iowa Energy Code standards are set at a baseline for high-performance public buildings. The new Library will exceed the baseline by 55% and will earn all 19 possible points in the LEED Energy Optimization Credit.

The HVAC system in the new Library will use Geothermal Heat Exchange that will substantially reduce overall energy consumption and the cost of operating the Library. For example, the 1985 Library building’s energy consumption averaged around 100 kbtu’s per square foot. The new Library is designed to consume only 37 kbtu’s per square foot, even though it is approximately 10 percent larger.

The exterior windows that comprises less than 30 percent of the exterior of the building have thermal isolation breaks to eliminate cold outside temperatures being tansferred to the inside surfaces of the frames. The glazing is high-performance, 1″ double-glazed insulating glass with a low e-coating which increases the insulating value and reduces Solar Heat Gain.

The exterior envelope of the new library has been designed to minimize “thermal bridges” and short circuits through the wall assemply. The exterior walls are designed as rain screen assemblies which allow the ventilated wall cavities to “breathe” and cut down and/or eliminate opportunities for mold growth in concealed spaces. The anticipated R-value of the non-glass, exterior walls is R-28.

The Library is designed to take full advantage of Daylight Harvesting techniques while minimizing glare on workstation surfaces through the strategic location of windows, large overhangs on the first floor, solar light tubes, and exterior sunscreens and automatically controlled perforated roller shades that are tied to daylight sensors in the staff work areas. The linear indirect lighting fixtures will use high-efficiency T5 HE florescent bulbs that reduce the watts per square foot consumed by the building.  The overhead lighting fixtures will also be tied to daylight sensors that will automatically dim or turn off all overhead lighting fixtures that are not needed to provide adequate illumination to the public spaces of the library during daytime operating hours.

The building will employ several strategies to manage stormwater on the site.  Twenty thousand square feet of the second floor roof will be developed as a green roof accessible to the public.  The green roof will absorb most of the stormwater that would have otherwise entered the storm sewer through roof drains.  The rainwater that falls on the remainder of the roof areas and paved hardscape of the site will be directed to underground water-quality vaults through pervious paving to allow it to naturally drain into the soil.  The objective is to retain 100% of all rainwater that lands on the site from all but an unusually heavy storm and preclude any of it from entering the storm sewer system.

The goal of the Board of Trustees and the Library Design Team has been to build a Library that will perform as efficiently as possible, both to reduce the environmental impact and to reduce the cost of maintaining our building. It is with this goal in mind that the team will continue to develop and build a Library that the City of Cedar Rapids will celebrate.

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