Built for Now, Designed for the Future
Small business played a key role in designing a LEED Gold facility for the Department of Veterans Affairs.
By Jeremy J. Wagener and Vishal G. Khanna, P.E., LEED AP
In Lincoln, Neb., a new facility for the U.S. Department of Veterans Affairs (VA) officially achieved LEED Gold status in 2012—the first office building in the city to do so. But this project is more than the realization of a certification, or the design and construction of an office facility, it is an example of engineering innovation to deliver a building that emphasizes longterm sustainability, a facility that harnesses geothermal energy and achieves numerous “green” building components—and was designed by a small business.
Advanced Engineering Systems (AES) partnered with Architectural Design Associates to design a new facility for VA’s Regional Office in Lincoln, Neb. The 66,000-ft² building, developed and owned by Hampton Enterprises and constructed by Hampton Commercial Construction, was designed to house nearly 270 VA employees who process benefit claims for veterans. VA also shares the office space with the Military Order of the Purple Heart, the Disabled American Veterans, and Paralyzed Veterans of America.
SEEKING HIGHER STANDARDS
One of VA’s primary goals for the new facility was to achieve LEED certification using LEED v2.2, which is a basic LEED rating. After strategizing on ways to construct the facility using green building techniques, the design team knew obtaining LEED certification would not be an issue. So they set their sights on a higher goal. The team obtained many additional LEED points in the categories of Sustainable Sites and Materials and Resources with the cooperation of the developer and general contractor—and did so without adding substantially to the cost of the project.
With these victories in mind, the team chose to pursue LEED Gold certification while maintaining the overall $14 million construction budget. While this would be a challenge, the team recognized that obtaining a LEED Gold rating was in the best interests of the owner and the VA due to the long-range benefit from long‐term energy cost savings.
AES focused on two main categories, Indoor Environmental Quality and Energy and Atmosphere, realizing the majority of the LEED points were going to be attained in these areas. Moreover, these improvements also would provide monthly energy cost savings that eventually could be passed on to the federal government.
Because a highly efficient HVAC system was crucial to their goals, AES compared many HVAC systems using analyzation software to determine which would offer the greatest energy efficiency and cost effectiveness. It was decided a geothermal heat pump system would be the most energy efficient in the long run while providing multiple zones in the building for temperature and human comfort. However, there were some issues that had to be overcome, notably the upfront cost of the geo‐system. Space constraints inside the building for the equipment and where to locate the well field/geothermal heat exchanger on the site also had to be addressed.
The team had to come up with a few design measures to help offset the initial cost in using this system. The placement of the heat pumps inside the building was an essential consideration for cost savings. To help with space constraints and to maximize the building’s usable square footage, the team designed a mezzanine in the attic. This allowed the majority of the heat pumps to be grouped together, saving dollars on hydronic piping and outdoor air ductwork that was connected to each heat pump. The units also were placed as close to the area they were serving as possible to minimize supply and return ductwork while keeping the ease of maintenance in mind.
Due to the size of the well field and the lack of green space on the site, 135 bore holes, each 300-ft deep, were placed under the parking lot adjacent to the building. While designing the well field, the team had to bear in mind that the field would receive less moisture than a typical field installed in a green space.
To help increase the energy transfer from the earth whenever possible, a few rows of bore holes were spaced at 25-ft on center in lieu of the current and commonly used 20-ft. This decision also saved in bore hole depth, resulting in cost savings.
There were a number of other significant energy conservation measures used to obtain the LEED Gold rating. Providing a supply of outdoor air is necessary to obtain good indoor air quality in any building. But bringing outdoor air inside requires energy to condition it before it is dispersed into the occupied spaces. Due to the large occupant load and square footage of the VA building, four packaged heat pumps with internal energy recovery wheels were used to precondition the outdoor air before it was ducted to the individual space heat pumps. Carbon dioxide sensors were placed in the breathing zones of the occupants to control the amount of outdoor air being supplied to the building. Variable frequency drives were positioned on the four packed outdoor air units. The building automation system (BAS) was used to control the speed of the exhaust and supply fans along with the energy recovery wheel based on the carbon dioxide levels in the spaces. These control strategies contribute significant energy cost savings on an ongoing basis.
Another cost saving application was connecting the lighting control system through the BAS. Daylight harvesting allows lights to be dimmed or turned off when natural light is adequate to light indoor spaces. In addition, the exterior lighting is controlled based on the amount of light. And private office control using occupancy sensors saves in operating costs. Using the BAS to control the lighting system allows the owner to monitor lighting systems easily and have one point of control for all of the building systems.
The facility’s HVAC system, in conjunction with the temperature and lighting control strategies, were the main ingredients to maximizing the overall energy cost savings. The building envelope, however, played an important role as well. The wall construction used for the proposed building was 38 percent better than the “baseline building” as determined by the current International Energy Code guidelines. The roof construction was 57 percent better. Adding extra insulating materials and using tinted, well insulated glass to the building envelope enabled the team to keep the heat pump cooling and heating capacities to a minimum.
INNOVATION AND FLEXIBILITY
Being flexible and innovative is fundamental to success as a small business. By exhibiting these qualities, AES was able to offer cost-saving solutions that were used to offset upfront cost so an energy efficient geothermal system could be used. This allowed the facility to obtain a LEED Gold rating while operating within the owner’s fixed budget.
With a projected payback in energy savings in just five to seven years, empirically, the decision to implement the geothermal system and to take the extra measures to obtain the higher LEED rating made sense, especially when considering the building will be occupied for many years to come.