July 29, 2004
Government finds gold at Sea-Tac Airport
By JOHN MARTIN
The Seattle Terminal Radar Approach Control (TRACON) facility at Seattle-Tacoma International Airport is the first FAA project to be awarded gold LEED certification.
Gold is the second highest level in LEED's Green Building Rating System, which is a voluntary, consensus-based standard established by the U.S. Green Building Council for developing high-performance, sustainable buildings. LEED stands for Leadership in Energy and Environmental Design.
LEED provides a framework for assessing building performance and meeting sustainability goals. Based on tested scientific standards, LEED emphasizes state-of-the-art strategies for sustainable site development, water savings, energy efficiency, materials selection and indoor environmental quality.
Designed by URS Corp. and McGowan Broz Engineers (mechanical and electrical), the 51,000-square-foot TRACON facility involved extensive site work adjacent to an environmentally sensitive wetland, which made stormwater and erosion control a high priority. A large knoll in the center of the site required excavating nearly 170,000 cubic yards of soil to establish a site platform and ensure handicap-compliant access from public transportation facilities to building entryways.
The architectural design uses natural lighting, glass floors, photo sensor lighting fixtures and recycled materials. Construction methods also complied with a stringent site-specific air quality and recycling plan that resulted in 95 percent of construction waste being recycled.
Part of airport master plan
The TRACON building, which supports airport activities at Sea-Tac, is part of the airport's growth master plan. The facility provides new administrative offices, electronic/computer radar control operations, and maintenance support spaces as part of the local and regional flight operations. The building is located west of the airport, making use of a previously developed site to minimize ground disturbance.
Specialty services provided for the project included geotechnical studies, site surveys, surface water management, access road design and electrical short-circuit studies. Also required were the design and siting of a detached generator building and prototypical guardhouse.
The design effort required the use of many sustainable concepts for all facets of the project, including site development, building materials and energy use processes. Compliance with the LEED program required efforts to be documented.
Achieving gold LEED
In order to achieve a gold LEED rating, the FAA and URS identified 14 specific design factors:
1. Use of recycled, renewable and reused building materials
2. Restricted use of toxic/hazardous building materials
3. Reduced indoor use of pollutants in building materials
4. Use of Xeriscape landscaping materials
5. Reduced site disturbance, specifically with regard to salmon habitat
6. Stormwater management of seasonal wetlands and a nearby creek
7. Water-efficient landscaping
8. Incorporating commissioning into the construction requirements
9. Measurement and verification of energy systems
10. Consideration of renewable energy sources
11. Thermal comfort of indoor occupants
12. Daylighting in appropriate rooms
13. Development of innovative sustainable features
14. Participation of a LEED-accredited professional
In response to these scope requirements, the project team took a proactive approach in defining opportunities to achieve the gold certification. A series of integrated team workshops was held to develop a list of specific applications, or credits, from the LEED scorecard. Participants included representatives of the user, owner and all disciplines of the design team.
Each of the LEED credits was evaluated as "easy," "moderate" or "difficult," based on the level of design effort and the construction process required to complete the credit. Items identified as easy were used and those seen as difficult were excluded. The moderate credits were reviewed and evaluated to determine which might be appropriate.
Conserving and creating energy
The best method for providing reductions in energy consumption is to make sure mechanical and electrical equipment have been sized to actual project needs and that equipment performs at optimum efficiency. This is accomplished through detailed, accurate system calculations matched to available equipment selection and the use of building commissioning to monitor and measure equipment performance. Both of those concepts were employed in the design and selection of the equipment to be used in the new buildings.
Because heavy electronic equipment with temperature and humidity controls was used, the building process loads accounted for 90 percent of the total energy-use loads. These loads are not adjustable nor can they be reduced to achieve LEED credits for the overall building energy reduction possibilities.
LEED, however, allows these energy loads to be considered as part of the baseline building requirements, which excludes them from the energy reduction calculations. The resulting energy calculations yielded a reduction in energy use of more than 10 percent over a base building scenario.
These results were achieved primarily from the use of daylighting with photocell sensors to reduce artificial lighting requirements, and displacement ventilation systems to reduce heating and cooling needs. Both systems feature individual occupant controls to maximize efficiency and improve indoor environmental quality of the occupied spaces. In addition, waterside economizers were used in the building's central chiller plant.
Preserving water and eco-system quality
The TRACON site was a residential neighborhood with single-family homes on large lots. It had minimal pavement, with one narrow, paved roadway into the interior of the property and driveways into each of the lots. The balance of the site was either left in natural growth patterns or included some landscape development.
After reviewing many other locations, the site was selected by the FAA as the optimum location for the TRACON facility. All attempts were made to protect surrounding wetlands and stormwater management features, and provide new landscaping, without hampering the physical security requirements of the occupants.
The site also offered good access to public and alternative transportation modes as well as protection of surrounding property occupants from conflict with lighting or other development features.
Limiting waste and recycling
While there was no building demolition waste, the project targeted 75 percent total salvage and recycling value from its construction materials. On-site land clearing waste was stockpiled and converted to soil and mulch. Soils removed from the site have been stockpiled offsite for use as fill for the airport's third runway. Topsoil was stockpiled on-site and re-used for plant material beds.
Products made of recycled content were specified for future use if they met the operational and functional requirements of the user. Through selection of many of the building materials, innovative concepts were used to make some of the materials serve purposes other than those typically associated with sustainable design.
Enhancing indoor air quality
Extended building commissioning and monitoring systems, as well as increased ventilation and thermal comfort controls, were used to verify that the quality of the air and temperature in occupied areas were healthy. Low VOC paints, adhesives, carpets and wood products improve these conditions by limiting the quantity of materials that can cause respiratory problems.
A psychological improvement to worker environments also is produced through access to exterior windows and direct line-of-sight visibility to windows.
LEED project results
The actual results accomplished have been documented and accepted by the USGBC as part of the LEED documentation review. Final tabulated results included:
These totals in most cases substantially exceeded the recommended levels of performance by the LEED guidelines, resulting in exemplary points being awarded as part of the innovation and design process.
While most government agencies use silver certification as the basis for their projects, the FAA made a commitment to achieve a higher standard to show what could be accomplished if the LEED process was followed from the beginning.
In addition to achieving gold certification, the project was completed ahead of schedule and within budget.
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