While the U.S. Southern Command (SOUTHCOM) was spearheading the Haiti earthquake response, the U.S. Army Corps of Engineers (USACE) was challenged with building Florida’s largest design-build project, the $280 million SOUTHCOM headquarters complex in Doral, Fla. SOUTHCOM had previously operated out of several separate Miami-area commercial buildings that were consolidated into one complex through this project. The 640,000-ft2, 55-acre, campus-style project was completed in just 27 months (including design), and was celebrated by a December 2010 ribbon-cutting ceremony. Meeting the challenge of building a sustainable SOUTHCOM headquarters complex resulted in an economic and environmental value to the public as well as a professional value to the military construction community.
As recently as 2005, Hurricane Wilma left millions of local residents without power for several weeks. Designers were challenged with how to reduce construction materials yet cope with the need for increased structural materials due to frequent large-scale hurricanes in Miami. The intent was to minimize the impact to the environment by using less structural steel, resulting in reduced need for raw materials, production, transportation and installation. The design team pursued a Leadership in Energy and Environmental Design (LEED) innovation in design credit for wind-tunnel testing. A scale model of the complex was built, put into a wind tunnel, and rotated 360° to determine the uplift forces at roof surfaces during a hurricane. The isotropic (equal pressure) lines on the diagram were used to depict wind forces experienced by various parts of the buildings. These wind-load forces were used to determine the most efficient use of materials. By using the localized wind loads from the wind tunnel rather than the standard blanketing of the building with code loads, designers made an estimated 22 percent savings in roofing, bracing and foundation steel.
The complex’s buildings are designed to endure winds stronger than 1992’s Hurricane Andrew (which obliterated nearby Homestead Air Force Base) and to be fully functional even under such extreme weather conditions. Redundant backup infrastructure will provide uninterrupted power during disasters. The team used careful planning to accomplish the very complex tie-ins and switchgear involved with implementing the cleaner choice of natural gas generators instead of diesel. The new complex provides the ability for SOUTHCOM to serve the nation’s interests without interruption despite such large-scale disasters.
Construction Materials Management
Not only must a design-build team manage the materials they use, but they must also manage the materials that are left over. Another great benefit to the environment was achieved through the construction waste management plan. During construction, waste was controlled at the source through use of a waste contractor that separated materials for recycling. In the end, 81 percent of all construction waste was recycled and diverted from landfills.
Enduring Cost Savings
The project was designed to achieve energy consumption levels that are at least 30% below the baseline levels of American Society of Heating, Refrigerating and Air-Conditioning Engineers Standard 90.1. This goal was achieved by optimizing design of the building envelope, including roof and wall insulation, energy-efficient windows and a high-performance reflective cool roof. Performance data were obtained with the help of a state-of-the-art building management system, which is used to monitor and manage the HVAC systems.
The Energy Policy Act of 2005 provides guidelines for reducing power used for lighting. The designers met the challenges of these guidelines by creating an energy-efficient lighting system, including occupancy sensors, fluorescent lighting fixtures and smart controls that control lighting output.
The old headquarters had rooftop air handling units as opposed to a central chiller system for the new complex. A lifecycle cost analysis of the HVAC system options and components was essential to finding the most economic choice during the design development phase. Chillers are available in much more efficient models and configurations than in the past. The high-efficiency central chiller plant in place only uses .57-kW of power per ton of coolant cycled, where older chillers used around .9-kW per ton.
Despite the obstacles of meeting increased military exterior lighting requirements and accommodating 24-hour operations, the team was able to get waivers from the U.S. Green Building Council and make impressive energy savings in other ways. Preliminary overall electrical usage comparisons between the old headquarters and new SOUTHCOM complex shows a more than 45 percent monthly reduction in kilowatt hours consumed per gross square foot of air conditioned building. This will pay huge dividends in lower utility bills, resulting in millions of taxpayer dollars saved over the lifetime of the complex.
Indoor environmental quality was a key goal and major attribute of the design. Although many building materials emit harmful volatile organic compounds, low-emitting materials were used throughout the SOUTHCOM complex to reduce the quantity of harmful indoor air contaminants. Special filters were used on the ventilation system to reduce particulates. Carbon dioxide sensors control the amount of fresh air to the building, reducing power usage for the HVAC system and ensuring occupant comfort. In the coming months, verification checks will help identify and correct any thermal comfort issues. Through the use of enhanced commissioning, the building’s proper performance will be confirmed after final completion.
Environmental and Community Benefits
Special large-scale retention ponds on the SOUTHCOM campus capture stormwater, which is then reused for site irrigation. This results in zero use of potable water for irrigation, reducing the burden on the surrounding community’s water resources. Many native tree species were used on the site, as well, as such species are accustomed to surviving Miami’s intense sun and five-month dry seasons.
There are opportunities to conserve water inside the buildings, too. Use of water-efficient aerators, toilets, low-flush urinals and sinks with automatic fixture sensors resulted in a roughly 30 percent reduction in municipal water use compared to baseline standards.
Carefully selecting materials can benefit the environment. The SOUTHCOM project used significant quantities of both recycled and regional materials during the construction. More than 20 percent of the construction materials used on the project consisted of recycled material content. While the benefits of recycled materials are obvious, regionally-procured materials also benefit the environment by conserving energy needed to transport thousands of tons goods to the jobsite, and more than 23 percent of the project’s materials were acquired from regional sources. The project used ceiling tiles made with recycled material and used wood from environmentally-certified sources.
Points toward LEED certification of a project can also be earned by incorporating alternative transportation ideas into the design. The SOUTHCOM project supports alternative transportation with ample carpool and fuel-efficient vehicle parking, bicycle racks, shower and changing facilities, and a planned bus stop.
In a time of recession and tremendous pressure on the federal budget, the SOUTHCOM headquarters complex project will be an enduring source of future energy and resource savings. Though the project was only required to be LEED Silver certifiable per Army Regulation 420-1, the project team is on track to earn the actual certification as one of their stated partnership goals. This project demonstrates that it is possible to achieve a design that stands up to nature’s challenges, satisfies the unique needs of the military, and is both environmentally and fiscally responsible.