The increasing world-wide emphasis on net zero (NZ) or low-energy communities (LEC) has brought with it requirements for high-quality technical analysis and optimization to support planners. The most ambitious goal is to become net zero relative to fossil fuels or to employ the concept of the energy-neutral community/campus. The achievement of this energy goal in economical and physically realistic ways requires new, unconventional approaches with respect to organization, implementation, funding, and technical decisions. The technical approach involves the emphasis on energy conservation, implementation of energy efficiency measures, use of waste energy streams, reduction of fossil-fuel-based energy, and/or complementation or replacement of fossil fuelbased energy with energy derived from renewable sources. This paper describes the process and results for an energy plan for the Portsmouth Naval Shipyard (PNSY), a historical installation with many energy needs and challenges. The energy planning process incorporates whole-building simulation, community-wide optimization of distribution and supply, geospatial data, and an overall approach to data organization that shows optimal approaches on retrofitting existing structures, standards for new building structures, optimizing the distribution system, and finally looking at supply options to meet the installation's energy efficiency and security goals. The results were computed using two different methods, a hand and spreadsheet calculation by a group of subject matter experts (SMEs) and with the U.S. Army Corps new Net Zero Planner (NZP) tool. The results from both methods are presented and compared and the results from both show several paths to meet the installation's stated goals and provide a project evaluation metric to meet these goals.