Abraxas Energy Consulting conducted an energy assessment for Corpus Christi Naval Health Clinic in Corpus Christi, Texas in November 2013. There are 2 buildings in the scope of this project at this facility: a 224,376 square foot health clinic and a 26,208 square foot branch health clinic. The goal of the audit was to assist Corpus Christi 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. Energy Star scores were calculated as 27 for the health clinic and 1 for the branch health clinic 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 twenty ECMs were recommended, as well as a list of administrative and operational measures that could be also implemented.
The largest opportunity for savings was found on implementing occupied/unoccupied temperature setbacks. Other ECMs found, affecting both or only one of the analyzed buildings, were increase of server room temperature setpoint, optimizing steam plant control, weatherizing entry doors, installation of PC management software, installation of flow regulators, retrofit backup generator with heat pump, occupancy controls for vending machines, installation of synchronous belts on AHU fans, replacement of decorative metal halide fixtures, retrofitting exterior fixtures with LED fixtures, addition of boiler blowdown heat recovery and flue gas stack economizer to steam boilers, upgrading of refrigerators, replacement of wallpacks, replacement of electric water heaters with a heat pump, addition of variable frequency drives to chilled water pumps and replacement of air-cooled chiller compressors with Turbocor compressors. 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 should be given further consideration due to the estimated payback of under 10 years. Regarding renewable energy sources, the feasibility evaluation recommended the implementation of a photovoltaic system to meet mandated renewable energy targets. Even though the system does not have a good payback, the location makes the opportunity more practical than at other Navy Medicine locations assessed. A full re-commissioning of the hospital building was recommended. The existing and proposed annual energy usage and cost for this project are shown below.
When implemented, the ECMs (including cogeneration, a photovoltaic system and retro-commissioning based on the feasibility study) will save over $814,824 per year with a simple payback of 5.9 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 6,700,573 kWh/yr, for gas the savings is -36,449 Therm/yr (due to the usage increase for cogeneration plant), and for water savings is 3,784 MGal/yr. Total energy savings results in a 27% 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.