Abraxas Energy Consulting conducted an energy assessment for San Diego Naval Medical Center in San Diego, California in July 2012. There is 1 building in the scope of this project at this facility: a 92,906 square foot training center clinic. The goal of the audit was to assist San Diego in identifying and developing energy investment initiatives that achieved the federally required energy reductions.
The energy assessment was performed in two phases, a Preliminary Assessment (Phase 1) and a Scoping Energy Assessment (Phase 2). Phase 1 consisted of a utility bill audit which established a baseline for energy and water usage and facilities benchmarking using energy Star Portfolio Manager. Twelve months of bills for water and gas, and electricity were used to conduct the audit. This generated a baseline for the energy/water/gas usage and utility costs, which was used in calculating potential energy savings. The calculated Energy Star score for the clinic was 6 and the goal after implementation of conservation measures was to reach a score of 75. The calculated HDDs and CDDs provided insight to potential energy conservation measures.
The second phase used on-site visits with the purpose of identifying and quantifying cost-effective energy efficiency measures, water conservation practices and renewable energy measures. During the on-site inspection all the relevant information on the existing building conditions was collected. This on-site assessment included reviewing building and equipment data, interviewing site personnel, observing energy related equipment operation, and conducting some limited site measurements. Based on the inspection and calculations eleven ECMs were recommended, as well as a list of administrative and operational measures that could be also implemented.
The largest opportunities for savings were found on installing air cooled chillers and replacing DX coils with chilled water coils. Other ECMs found were installation of cool roof, installation of synchronous belts on package unit fans, upgrade and conversion of heating hot water system t variable flow, lighting upgrade, installation of occupancy controllers in vending machines, replacement of the boiler with high efficiency condensing boilers and retrofitting and replacement of water fixtures. Studies were also conducted into the feasibility of co-generation, renewable energy sources and retro-commissioning. These were preliminary assessments and based on the results, co-generation and renewable energy sources were not found to be cost effective. A full re-commissioning of the building was recommended after the controls upgrade has been completed. The existing and proposed annual energy usage and cost for this project are shown below.
When implemented, the ECMs (including retro-commissioning based on the feasibility study) will save over $116,751 per year with a simple payback of 7.9 years. The list of measures is prioritized by simple payback such that short term investments are expected to be implemented first and longer term investments implemented last. Some interactive effects are accounted for in the calculation of energy savings such that if a different implementation sequence is followed the savings realized will vary to a degree. Total savings for electricity is 797,143 kWh/yr and 84.3 kW/yr, for gas the savings is 23,529 Therm/yr, and for water savings is 237 HCF/yr. Total energy savings results in a 38% reduction in energy intensity. All values were evaluated using bin simulations and spreadsheet calculations based upon standard energy savings estimating methods and known and assumed operating conditions. Various incentives were identified through utility companies and various federal programs.