Figure 1. Fort Bragg is home to numerous commands, as well as 44,000 soldiers and their families.
Fort Bragg in Fayetteville, NC is one of the largest, and most well-known Army installations in the world. It is home to the 18th Airborne Corps, the 82nd Airborne Division, Special Forces Command, and numerous other commands, as well as over 50,000 soldiers and their families.

The base was built more than 80 years ago, and, like many federal facilities, the mechanical systems have not always been optimally maintained or operated. In addition to aging equipment, years of deferred maintenance and budget cuts have resulted in equipment that doesn't work properly, system-wide decay, and central plants that are beyond capacity.

Upgrading all of Fort Bragg's mechanical systems at one time would be extremely expensive, so a decision was made in the late 1990s to phase in new equipment and systems through performance contracting. To that end, Fort Bragg's Directorate of Public Works (DPW) devised a unique public-private energy services team structure to aggressively manage the energy supplied to the base and to implement projects that would maximize efficiency and reliability.

The program has been a resounding success, and in 2003, Fort Bragg's comprehensive Energy Management Modernization Program delivered $8.131 million in savings and used 162,993 fewer MMBtu. Just as importantly, the program has allowed the base's soldiers and their families to experience better, more reliable comfort.

Figure 2. As an 80-year-old base, Fort Bragg has numerous different types of HVAC equipment, most in need of upgrading or replacement.

Establishing A Partnership

The DPW staff consists of less than 300 employees who provide all public works functions at Fort Bragg. Given that the base has over 32 million sq ft of facilities to maintain, the staff is stretched to its limits.

Greg Bean, director of public works, noted, "We are responsible for the maintenance and repair of nearly 5,000 buildings, including 229 barracks with over 15,000 barracks rooms. The barracks are old, and for years, we haven't had the money to properly maintain the facilities. For example, the soldiers' rooms usually have a fancoil unit with an air filter. I'd go in and check the air filter, and often it would look like a horse blanket. And you wonder, ‘Why doesn't the solider have heat or air?'"

Leaky pipes were another big problem, according to Bean. "The chilled water pipes had 50-year-old insulation, which of course, had rotted over time. With 45°[F] chilled water going through a copper pipe then hitting 90° air and 90% humidity, you'd get buckets of condensation. And, of course, the condensate drains were plugged up or else condensate pans had been dislodged."

It was obvious that there were just too many facilities in need at Fort Bragg, so DPW put selected contractors in place to help manage the base's energy-related operations. Honeywell International was chosen as the energy savings performance contractor in 1998.

"At that time we put together an integrated solutions team, which basically involved the key personnel from the base as well as Honeywell personnel to start evaluating the opportunities in performance contracting on-site," said Richard Rogan, performance contracting engineer, for Honeywell Building Solutions, Golden Valley, MN.

"The most important aspect of a performance contract is we're able to leverage someone else's money to fix the systems that aren't working," said Bean. "We've got great soldiers who work hard every day, and they deserve to live in the same conditions as the public they protect. This includes having reliable heating and air conditioning."

The goal of the performance contract was - and continues to be - to decrease emissions, repair and modernize the facilities and the infrastructure, and increase energy security and flexibility. With all that in mind, the team started looking for opportunities to increase efficiencies and came up with 11 large-scale task orders, which incorporated a variety of upgrades.

The initial opportunity under the performance contract was to retrofit many of the buildings with energy-efficient lighting, as well as install occupancy controls and use daylighting whenever possible. After the lighting retrofit came building envelope opportunities, which included installing low emissivity glass and insulation.

Other demand-side opportunities, such as replacing old and/or inefficient motors with high-efficiency motors and replacing inefficient HVAC components with high-efficiency ones, were also employed. Control strategies were also implemented, such as setback, set-up, and temperature resets. Many overridden control systems were recommissioned, and some remote monitoring and control capabilities were provided.

Figure 3. An 1,000-ton absorption chiller, which is part of the cogeneration system, basically runs off of the hot gas exhaust from the turbine.

Going Beyond Conservation

After the initial demand-side strategies were put into place, it became clear that reducing consumption was not going to allow the infrastructure improvements that needed to be accomplished. Fort Bragg and Honeywell subsequently put together a method of capturing savings that would be generated by managing the base's energy supply.

"We started by negotiating a new power supply contract, which is based on real-time power pricing," said Rogan. "The majority of Fort Bragg's energy is purchased in advance at a very low cost. When the base goes above that contractual amount, Fort Bragg is subject to the real-time price of energy, which fluctuates based on the amount of generation available, as well as the weather." A new contract was also negotiated with the natural gas utility.

Obviously there is a bit of risk associated with being at the mercy of real-time pricing, so Fort Bragg's numerous emergency generators were retrofitted with grid-paralleling switchgear. With this configuration, it is possible to dispatch the generators when the price of energy is high or when a demand peak is nearing.

As Bean noted, "We're really working on managing the peak demand. It's one of those great, never-ending do-loops: If you don't spend money on the equipment, it gets worse, which makes you less energy efficient, so you're spending more money on energy, therefore you're not spending money on maintenance, so then your system is less reliable, and you go in a deep hole. Whereas, if we can do it the other way, we can take our savings to make the base more efficient."

As part of the newly negotiated power contract - and to stave off peak demand charges - a 5-MW solar turbine was installed. Fort Bragg's peak load is in the neighborhood of 110 MW, but the additional amount generated by the solar turbine keeps the base at the consumption level agreed upon with the utility. Since Fort Bragg continues to expand, the extra 5 MW is enough to neutralize the effect of that growth for the time being.

When installing the solar turbine, other economics were needed in order to make the proposition cost effective. At the plant where the turbine was placed, a 1,000-ton absorption chiller was installed, which basically runs off of the hot gas exhaust from the turbine. Between supplying chilled water in the summer and steam and hot water in the winter, there's enough load to operate the turbine year-round, thus squeezing out the maximum efficiency.

Once the new contracts were in place with the energy providers, significant savings were freed up that could be applied for further infrastructure improvements. Honeywell used those savings to begin the implementation of an energy information and control system in order to get a backbone of information systems and metering in place.

"We needed to understand what was occurring at the largest facilities on base," said Rogan. "This included 11 central plants, which supply steam, hot water, and chilled water to hundreds of buildings. If you don't understand the plant's current operating efficiencies and where the inefficiencies are, it makes it difficult to propose solutions. We implemented this metering system and began to gather data and gain an understanding of the existing plants and the buildings that they served."

Figure 4. Many of the existing large oil-fired boilers at Fort Bragg have been retrofitted with dual fuel capabilities, so it is possible to use oil or natural gas.

What Was Found

Not surprisingly, the new information system pointed out numerous problems with the central plants. That's not really unexpected, said Rogan, because most federal bases have been hurt by insufficient operating budgets over the past 10 years. "Due to that, the mechanical and the electrical infrastructures are decaying. Equipment is not maintained properly. It's not necessarily operated properly either. But with the backbone in place, we started to evaluate and then to make recommendations for retrofits and changes in the way that the central plants operate."

Each plant at Fort Bragg was evaluated in order to determine what kinds of problems existed. In one case, it was found that a high-temperature hot water plant, which supplied building heating water as well as domestic heating water to 50 or 60 buildings, operated year-round even though it only supplied domestic heating water in the summer. There was also a significant loss associated with the plant's underground distribution system.

To solve the problem, natural gas was piped to the individual buildings and high-efficiency domestic water heaters were installed, which enabled the plant to be shut down for about six months out of the year. This arrangement eliminated all the parasitic losses of the plant itself, as well as reduced wear and tear on the central boiler systems.

Some of the plants were decommissioned and later demolished, while others received extensive upgrades. Three constant volume plants became primary/secondary systems thanks to piping and pumping modifications as well as VSDs. These plants now adjust to the load of the day, versus operating at full-load capacity.

The chilled water, steam, and hot water distribution systems were in various stages of decay, and Honeywell has been methodically replacing piping throughout the base. Another opportunity to save energy arose when it was discovered that in one of the plants, no condensate was being returned from the buildings it served. The entire condensate loop was replaced, resulting in a $1 million annual energy savings.

Many of the existing large oil-fired boilers have been retrofitted with dual fuel capabilities, so it's possible to use oil or natural gas. This enables Honeywell to better manage the gas contracts as the base approaches its nominated volumes. If this occurs, or if there's a spike in natural gas pricing, the boilers can easily be switched over to oil.

"When you're trying to manage supply contracts in a facility this large, flexibility is extremely important. That gives you some security as well," said Rogan. "If Fort Bragg were to lose the natural gas line that feeds the base, there's oil on hand, and the plants can all run on it. It's part of an energy security strategy and also reduces the risk associated with market fluctuations in gas, oil, and electricity."

Figure 5. This boiler plant control room allows Fort Bragg personnel to closely monitor heating conditions throughout the base.

Part Of The Team

Honeywell became an "official" part of the base in 2001 when Fort Bragg asked the company to take over the O&M of its 11 central plants. "The Honeywell people are embedded throughout my staff," said Bean. "They are as much a part of my maintenance staff as my in-house maintenance staff. They bring skills and technology that I could not have otherwise brought to solve our problems and enhance our operations."

While the arrangement has allowed the plants to receive better maintenance and more upgrades, there is a seemingly never ending list of improvements that still need to be made. Bean believes that they're making progress but that it's going to take at least a decade to get caught up on the maintenance.

"The first time I worked in facilities, someone at the Pentagon told me that there are four questions you have to answer: ‘Where am I? Where do I want to be? What's my plan to get there? How much does it cost?' We pretty much know where we're at, we know where we want to be, we're working through the plan and trying to get numbers to go with it. But it takes a sustained funding level to be able to execute that plan. That's the biggest challenge I face: Making decisions on how to best apply our scarce resources and trying to ensure that we have a sustained funding level to make the improvements we need to support our infrastructure," Bean said. ES

Figure 6. The energy information system (EIS) is the backbone of the base’s new energy-saving program. The EIS allowed Honeywell to recommend retrofits and changes in the way that the central plants operate.

Partnership Projects

Since the partnership began, Honeywell has undertaken more than 23 major projects to reduce energy consumption and costs at Fort Bragg. These include:

  • Expanding the post's limited underground natural gas distribution system with a new system that provides extended natural gas use at the post.
  • Installing new, high-efficiency, natural gas-fired steam and hot-water boilers to replace one of the post's outdated central steam plants.
  • Converting warehouses, vehicle maintenance facilities, and hangars from forced induction heating to radiant heating, which has improved working conditions.
  • Upgrading the central plants with new chillers, cooling towers, VFD motors, and new controls, and providing full-service maintenance.
  • Extending existing post-wide HVAC automation to DDC to provide 24-hr control and monitoring of mechanical systems.
  • Replacing aging and oversized centrifugal chillers with ones that use a third of the energy.
  • Installing high-efficiency lighting, including lamps and ballasts, throughout the post.