Presidential Center sets example on LEED[R] requirements.

All presidential libraries must meet the environmental, operational and redundancy standards or the National Archives Administration (NARA).

The NARA guidelines are specific and demanding with respect to the control of temperature, humidity and gaseous contaminants within the various spaces contained within a facility of this type. While we typically associate strict environmental conditions with traditional archival spaces, similar demands are based on the more public spaces, such as the exhibition areas of the Presidential Museum. These spaces are highly architectural and introduced many design challenges.

For example, to create the visual link between Little Rock and the Presidential Center, it was proposed to construct the west exposure of the building entirely of low iron clear glass. While the glass wall was a beautiful expression, the clear glass created extremely large cooling loads.

Flack + Kurtz in conjunction with the Polshek Partnership analyzed many wall configurations to maintain the desired architectural effects and decrease the associated cooling load.

Ultimately, the glazing system consisted of a glass wall which defined the building envelope and secondary exterior glass wall across a walkway creating a variation of a double envelope system more often used in Europe. The glass that defined the building envelope was an insulated assembly of low iron clear glass. The number 2 surface of the assembly had a high performance coating on it which reduced the energy of the sun by 55%.

Outside the building is an elevated walkway with an additional piece of clear laminated glass on the outboard side of the walkway. The heat absorbed by the glass was vented through louvered elements in the top of the walkway. The system reduced the heat gain by 65%.

The cooling loads due to the large glass areas and the lighting loads were still significant.

A radiant floor was proposed. Radiant floors are extremely effective in removing the absorbed heat of the sun and the absorbed heat from high power display lighting. Energy impingent on the floor is directly absorbed into the radiant cooling water loop. The energy efficiency of a radiant cooling system is greatly improved compared to an air system. Water has a greater heat capacity than air and less water mass is required to be circulated than in an air system.

Air delivery is still required to provide ventilation and humidity control to the space. The use of displacement ventilation was used where possible. These systems allow the temperatures in the space to stratify and essentially provide cooling to the occupied zone. In a displacement air supply system, the air is cleaner because it is provided to the occupied zone.

Compared to a typical code compliant building energy consumption in this project was reduced by 35%. The reduction was achieved by integrating the features into the building in a logical way. The energy responsible design was incorporated in the core goals of the project. In our experience, projects that proceed based on an integrated approach are more successful with respect to capital cost, operating cost and overall design of the project.

The William Jefferson Clinton Presidential Center is an example that the visions and requirements of energy responsible design which is a core value of LEED[R] can be met. The design and construction of the project included an integrated approach from its inception. The designers and contractors were open minded and approached the design in a manner that permitted the lofty goals of the project to be attained.

GARY POMERANTZ, PE, SENIOR, VP, FLACK & KURTZ