Active Efficiency in Action

The best way to understand the value of Active Efficiency is to see it in action. There are many examples that demonstrate the potential of Active Efficiency. Between the economic, social, and environmental benefits, the hard work that goes into making these examples successful is something to be celebrated.

Ameresco’s Active Efficiency Approach at Parris Island


The U.S. Department of Defense (DOD) is the largest energy consumer in the country. While DOD is a mission-critical institution with its top priority to protect the nation, it is increasingly exploring the security implications of climate change. In 2018, the Pentagon reported that climate change threatens activities on about half of its bases worldwide. This will become increasingly costly as natural disasters escalate. As a result, DOD is both interested in understanding how to respond to the security threat posed by climate change, and how it can leverage its leadership to advance decarbonization.

The U.S. Marine Corps Recruit Depot (MCRD), Parris Island is an 8,095-acre military campus that houses up to 20,000 Marine trainees annually. Given its location in Port Royal, South Carolina – a region prone to devastating hurricanes and tropical storms – resilience is valued at a premium. Continued operation during a utility grid power outage is pivotal to continuing the mission-critical activities at MCRD. In 2015, MCRD selected Ameresco, an energy efficiency, infrastructure, and renewable energy solutions provider, to complete a comprehensive energy optimization project that would bolster resilience.

The result was one of the most comprehensive energy retrofits undertaken at a U.S. Marine Corps facility, covering more than 120 buildings, and provides a model example of a comprehensive Active Efficiency strategy. Through the project, Parris Island has to date reduced its utility energy demand by 75%, reduced its annual emissions by more than 37,000 metric tons of C02, and has reaped an estimated annual cost savings of $6.9 million.

How they did it

These savings were made possible by Ameresco’s Active Efficiency approach: combining foundational energy efficiency upgrades including LED lighting upgrades, HVAC equipment improvements, building controls upgrades, and site water efficiency measures with a range of integrated, time-dependent energy solutions. The project included solar photovoltaic arrays and a multi-fueled combined heat and power (CHP) (which recovers waste heat from electrical generation to support process loads, space comfort, and domestic water heating), which were installed on site yielding generation capacity of more than 10 MW. That on-site generation capacity coupled with 4MW/8.1MWh of lithium-ion battery energy storage and a smart microgrid control system allows flexibility for optimizing on- and off-grid operation based on MCRD’s demand and available on-site supply.

In addition to responding to supply and demand signals to optimize energy usage, Parris Island’s microgrid control system, on-site generation, and storage resources allow for MCRD’s facilities to continue to operate in the event of a grid outage. Crucially, the foundational efficiency improvements made as part of the project helped chart the path to independence from the grid and for demand flexibility by minimizing energy waste in the system.

Security is top priority for DOD, and the digital nature of the energy technologies implemented meant special consideration had to be given to cybersecurity. Additional security measures were taken when implementing the Parris Island microgrid control system to close off potential cyber vulnerabilities and improve system management and administration. These measures guard the customer’s investment in efficiency and resiliency.

Hannon Armstrong Sustainable Capital funded the project through an energy savings performance contract, requiring no upfront costs from DOD. The energy and water savings from the improvements will repay the contract over a 22-year performance period.