Energy Savings at Military Installations: A Case Study *Stavropoulos, G.G 1 1, 2, 3 and Skodras, G. 1 Lab of Chemical Process Engineering, Aristotle University of Thessaloniki, Thessaloniki, Greece 2 Laboratory of Environmental and Energy Processes, Chemical Process Engineering Research Institute, Thessaloniki, Greece 3 Institute for Solid Fuels Technology and Applications, Ptolemais, Greece *P. O. Box 1520, Thessaloniki, 54006 Greece Tel :+30 31 995918, Fax +30 31 996168 E-mail: gstaurop@cheng.auth.gr Abstract Military installations are large energy consumers in many countries. In order to evaluate energy saving possibilities in such facilities an energy audit was conducted in a typical military campus. The audit objective was to provide background for similar applications in all military facilities. In the energy audit were included buildings design and envelope and energy systems such as HVAC systems, water heating, lighting, electrical power systems and other. Audit results and recommendations were consisted in a series of proposals for energy saving measures. For each measure the preliminary cost estimate was provided together with the economic evaluation in order to form an investment plan that could be funded from the department of the defense. 1. Introduction The ever-increasing energy costs and environmental concerns make paramount the rational use of energy and the energy conservation acts. Attention must be paid both in the industry and the building sectors. The last has attracted considerable interest in large scale, country wide, and in small scale, for example residential apartments. Governmental and generally state-owned buildings, especially the old ones, are good candidates for conducting energy audits and proposing energy conservation opportunities. Government officials accept easily the idea of audit and collaborate
with auditors. Universities and schools, hospitals, sports facilities, prisons and other, can be included in the list of energy auditing teams. Military installations include in large part buildings for various uses and energy saving possibilities are expected to be substantial. Many of them are old and present similarities in the building construction and in the other facilities and services because they follow common military codes and practices. Based on the above considerations, an energy audit was carried out in a typical military campus. The audit implementation mode and recommendations may serve as a guide for audits in military campuses country-wise and/or to form a basis for estimations of energy saving investment possibilities in the defense sector. 2. Scope The scope of the audit was to cover any energy consuming activity in the campus. They were included buildings envelope, heating, ventilating and air conditioning systems, (HVAC), lighting, electricity and water systems. Special emphasis was given in the renewable energy sources. 3. Methodology An audit team was formed by two persons, one been an energy engineer and the other a technician for taking measurements. A checklist (questioner) of all energy consuming devices was set-up, including necessary measurements in order to register the existing conditions. Portable instrumentation was provided for this purpose. The team has visited the site and took all data, which then were discussed and verified with military personnel. During the completion of the study, emerging proposals were also discussed with personnel in order to have input on the possibility of implementation of the energy saving actions. In the present paper, the audit results will be presented. The presentation will be separately per item. For each item, the existing situation and the proposals will be described. Also, the cost estimate and the economic incentive will be given.
4. Results and Discussion 4.1 Space heating Most medium-to-large buildings use boilers to generate hot water for space heating and food preparation. For boilers to run at peak efficiency, attention must be given to boiler control, insulation, fuel-air mixtures, and stack temperature. Efforts should be made to upgrade existing boilers or replacing old equipment. Solar systems or biomass-fired boiler will also be considered. The military campus under investigation consists of three buildings served by four Diesel oil boilers. In Table 1, the most important characteristics and operating conditions of the boilers can be seen. Boilers are relatively new, operate under good conditions of control and have a satisfactory maintenance. Data collected during the audit were screened for energy conservation possibilities. A large number of such possibilities were considered including heat recovery, combustion controls, boiler and fuel replacement etc. The following measures resulted. Flue gas heat recovery Use of natural gas to substitute oil The first is justified from the high flue gas temperature (except boiler No 3), actually 240-250 C, versus the 190 C minimum allowable for diesel oil boilers. The second was proposed because of the anticipated economic and environmental benefits of the natural gas. 4.2 Building envelope Building envelope controls the flow of energy between the interior and exterior and consists of walls, roof, windows, and doors. It is important that all components are designed and constructed according to energy saving practices. In table 2 the characteristics of windows are shown. Given that buildings are erected in climatic
zone B, window glazing must be replaced with improved type double-glazing, especially for windows of N-S orientation. There are 11 doors in the buildings, custom made with iron and single glazing. The substitution of single with doubleglazing is recommended. Walls were found in good conditions although without insulation. On the contrary, roofs were well insulated. 4.3 Water heating Hot water is used for showering, cooking, dishwashing, hand washing and laundering. Public buildings often have significant hot water needs in one or more locations scattered throughout the facility. Methods for reducing the energy used to generate hot water consist mainly in reducing water consumption and temperature; reducing losses; and utilize waste heat sources and appropriate technologies, including solar water heating. Hot water is used in the campus in baths, cooking and other minor uses. Water is heated in the boilers. As the required water temperature for those services is low, water can be heated in solar collectors. The solar water heating system will operate in conjunction with boilers to cover heating needs during cloudy days. 4.4 Electrical power systems Electricity is the largest energy source in most facilities. Electric utility bill include both energy charges and power demand. Utilities penalize low power factors. Power systems include HVAC equipment, lighting, kitchen appliances, wiring and plug loads that deliver power to the end users. Electrical power systems are often stable, reliable and have little potential for saving energy. However there are often opportunities for improving efficiencies of electrical systems especially whenever renovating or replacing equipment. The electrical system in the military campus was found to simple and reliable although not very new. Simple maintenance and minor component changes are required. 4.5 Lighting Lighting is a major electricity consumer. Retrofitting of the lighting system must be undertaken. A common electricity saving possibility is the replacement of existing incandescent lamps with compact fluorescent lights, (CFLs). The energy audit in the campus showed that on a total number of 960 lamps, 300 were incandescent and their
replacement with CFLs is recommended. No needs for occupancy sensors in unoccupied spaces were determined. 4.6 Renewable energy Renewable and alternative energy sources (solar, wind, hydro, biomass) are depleting fossil fuels in increased rates. Among various technologies, power generation possibilities in the campus were investigated with the use of photovoltaics, which are beginning to emerge as strong competitors of conventional power systems. It was found that the most appropriate use of these systems was in exterior lighting in many remote locations of the campus. The systems should be used separately in each point and should be compact including the collector, the battery and the system control. Further all systems should have a parallel connection to the campus power supply system in order to supply or withdraw power according to its operation which depends on whether conditions. Another application of photovoltaics of rather pilot character that was found well suited for application in the military campus was the transportation of personnel within the campus with solar vehicles. Cars used should be battery operated. Discharged batteries should be recharged by a system of photovoltaics installed in the campus. 4.7 Biomass The use of biomass presents significant energy and environmental advantages. One of the most efficient uses of biomass is the cogeneration of heat and power and advanced biomass power generation equipment. A promising system is the Organic Rankin Cycle, (OCR). Biomass is burned in boiler and heats thermal oil, which is fed to a Rankin cycle turboexpandor (HER). The HER produces electricity and hot water which is used in space heating. Biomass energy is most feasible when there is a nearby source such as wood or waste-wood, (from wood manufacturing, agricultural crop residue). On the other hand, in most countries, army uses wood in considerable amounts in wood stoves for space heating. Those considerations guided the audit team to screen the possibility of the installation of a small compact OCR unit in the campus. As fuel should be used wood and wood waste from a nearby particleboard industry. The unit should be used primarily to satisfy the heating needs of the campus. The excess electricity will be diverted to the public grid.
It can be seen that the most promising energy saving measures are the solar heating, flue gas heat recovery and the lighting improvements. Costs are relatively small depending on the size of the buildings and on the fact that regard mostly changes in existing structures. On the other hand, improvements in buildings shell (windowsdoors) gives almost double payout period making this investment of limited acceptability. Indeed this is a capital-intensive measure of low income. Savings are due to heat loss reduction, which are not so high. Natural gas use is also at the same category mainly because of the critical difference between gas and oil prices. The biomass use as fuel replacing oil gives a pay back value larger than 10 years basically because of high capital investment. 10 years is the limiting value of SPB for energy conservation investments to be accepted and is currently adopted from many organizations. With this criterion already used to evaluate measures, the use of natural gas is more attractive than biomass although of limited economic interest. Measures like photovoltaics and solar cars were not included in the economic analysis due to their pilot character. 5. Conclusions Energy conservation possibilities in a military campus were undertaken in this paper. All actions regard buildings and concentrate in space heating, hot water production and lighting including boiler efficiency improvement, solar heating and energy efficient lighting. Except of this retrofitting actions, more advanced possibilities were included focusing on renewable energy. Photovoltaics were found to be of practical applicability in the campus for power generation in modular systems that can fed lighting or charge batteries used in electric cars. References [1] Energy Efficiency Manual, D.R. Wuefinghoff, Energy Institute Press, Maryland 2003, USA [2] International Energy Conservation Code 2003, The International Code Council [3] Greening Federal Facilities, US Dept. of Energy, 2 nd edition, May 2001
Table 1. Space heating boilers Building No Boiler No Fuel Consumption (m 3 /year) Flue gas temp. ( C) Soot in flue gases 1 1 Diesel oil 46 both 250 2 2 Diesel oil 250 2 2 3 Diesel oil 32 190 1 3 4 Diesel oil 76 240 2
Table 2. Windows Building No Orientation Total area, m 2 Glazing Material Air leaks 1 E-W 950 Single Iron No 2 N-S 405 Single Iron No 3 E-W 270 Single Iron No
Table 3. Economic evaluation of the energy conservation measures Investment proposal Cost, K$ Pay back period, yrs Flue gas heat recovery 12 4.1 Solar water heating 24 4.0 Improved windows-doors 100 9.8 Lighting 5 5.0 Natural gas 50 10 Biomass 650 >10