Improving Sustainability
The key to improving sustainability through operations and maintenance is to be aware of opportunities and to take advantage of them. This report describes ways to identify your opportunities. This report describes ways to identify your opportunities.
Choose improvements that are cost effective over the life of a building. Elaborate shading to reduce unwanted heating by the sun may be cost effective for buildings in Arizona or Puerto Rico, but not for buildings in southeast Alaska. In contrast, upgrading to an ultraefficient heating system may be cost effective in Minnesota or Alaska, but not in Florida.
An energy audit, which may be free through your local utility or State Department of Environmental Quality, can identify cost-effective measures to reduce energy use.
- See the Forest Service internal Web page (http://fsweb.wo.fs.fed.us/eng/programs/facilities/sus_green/audit.htm) for more information on energy audits.
Sometimes energy audits recommend retrocommissioning to investigate energy-saving opportunities for complex heating, ventilation, air conditioning, and building control systems.
Commissioning is a comprehensive process that examines all of a building's operating systems and identifies changes needed to optimize the building's performance and satisfy the owner's operational needs. Changes that can be done quickly usually are completed as part of the commissioning process. More elaborate changes are scheduled for completion later, often by other specialists. Retrocommissioning is the term used for commissioning an existing building that has never been commissioned. Recommissioning is performed on buildings that were commissioned during construction.
Both retrocommissioning and recommissioning focus on equipment that uses energy. Heating, ventilation, air conditioning (HVAC), and building control systems often have significant problems that nobody's aware of. Fixing these problems can save a lot of money over a few years.
Commissioning can identify opportunities for savings in both new and old buildings. For instance, the Forest Service's Missoula Technology and Development Center (MTDC, figure 2), was built in 2002. A 2005 review of the HVAC system found that nearly 30 percent of the solenoids for the heat valves on the air distribution boxes weren't working properly. The system also had other minor glitches. Fixing these problems meant MTDC's energy bill remained the same during the winter of 2005 and 2006 compared to 2004 and 2005 even though energy rates increased about 20 percent. The system review and repairs more than paid for themselves the first year after they were completed.
Figure 2—The Forest Service's Missoula Technology and Development
Center
in Missoula, MT, was designed to be cooled using well water
instead of refrigeration
and heated using very efficient boilers.
Energy use was reduced 20 percent
by repairing solenoids
that control valves in the air distribution boxes.
Large buildings or groups of buildings with complex heating, ventilation, air conditioning, and control systems may benefit from retrocommissioning or a similar process if they are experiencing any of the following four problems:
- Airflow or pressurization problems
- Recurring equipment failures
- Indoor air quality or temperature control problems
- High energy bills compared to similar buildings
According to the Northwest Energy Efficiency Alliance and its partner utility companies, the energy costs of big buildings with any of the four problems listed above can be reduced by 5 to 15 percent. Other savings will be gained from improved employee productivity and lower operations and maintenance costs.
Commissioning costs a lot—an average of 25 cents per square foot for an existing building. However, the payback time in energy savings for complex equipment is usually less than 5 years.
- More information about commissioning is available at the Northwest Energy Efficiency Alliance's Web page (http://www.betterbricks.com/default.aspx?pid=commissioning).
When energy was cheap, it didn't matter much whether equipment and systems were efficient, so most of them weren't. However, even older, inefficient equipment works better if:
- Distribution systems don't leak and are properly insulated
- Coils, burners, filters, and ductwork are clean
- Burner and refrigerant pressure are adjusted properly
- Everything is in good repair
Yearly equipment checks, servicing, and adjustment ensure that equipment and systems are working properly. This is NOT the place to skimp on the operations budget—you'll pay more later if you do.
In areas with low energy costs or mild climates, it may be cost effective to perform thorough maintenance and hang onto older inefficient systems and equipment until they fail. In areas with high energy costs or harsh climates, it may not be worth refurbishing and retaining older systems or equipment because just a few years of energy cost savings would pay for new equipment.
To get the most out of old or new equipment, upgrade the building envelope and insulation as described in the Building Envelope section. Doing so will ensure that existing equipment doesn't use more energy than necessary and will allow new equipment to be sized appropriately, so it will operate more efficiently.
Forced-air furnaces and hot water systems manufactured before about 1990 had efficiencies in the range of 56 to 70 percent. Today, standard heating systems have efficiencies of around 80 percent and some systems may be 97 percent efficient, converting nearly all fuel to useful heat. Especially where fuel costs are high, it can be cost effective to replace old, worn out, inefficient, or significantly oversized furnaces or boilers with modern high-efficiency models. Old coal burners that were converted to oil or gas are prime candidates for replacement, as are gas furnaces with pilot lights rather than electronic ignitions.
Have a mechanical engineer or heating contractor run a heat-loss calculation to size your new furnace. In cold climates, it usually makes sense to invest in a system with at least a 90-percent efficiency rating. In milder climates with lower annual heating costs, the extra investment required to go from 80- to 90-percent efficiency may be hard to justify.
- More information on furnace replacement and energy-efficient furnaces is available at the U.S. Department of Energy Web site (http://www.eere.energy.gov/basics/buildings/furnaces_boilers.html).
Consider including other newer technologies when replacing furnaces and boilers. Preheating devices use radiation fins between the intake and exhaust air (air-to-air heat exchange) or heat from the sun on a large surface (solar preheating) to warm the intake air or water so the furnace or boiler doesn't have to work as hard. Passive solar heating or systems to preheat furnace or ventilation intake air or boiler water may be cost effective in areas that get a lot of winter sunshine.
In areas where biodiesel or wood chips are readily available, consider a furnace or water heater designed to use biofuel.
- Information about wood chip furnaces and boilers is available in the publication Wood-Chip Heating Systems (http://www.biomasscenter.org/pdfs/Wood-Chip-Heating-Guide.pdf) and at the Fuels for Schools and Beyond Web site ( http://www.fuelsforschools.info/).
Ground-source heat pumps are energy-efficient systems that provide significant cost benefits in many areas. These systems use the relatively constant temperature below the frostline as part of a refrigerator-like system that harvests heat from the ground in the winter and dumps excess heat into the ground in the summer. Your unit's facilities engineer or your regional mechanical engineer is a good source of information on what's practical in your area.
Cooling equipment efficiency has improved about 20 percent since the mid 1990s. In addition, chlorofluorocarbon (CFC) and hydrochlorofluorocarbon (HCFC) refrigerants commonly used before 1995 are being phased out and will become increasingly more expensive and difficult to obtain. Although air conditioners and heat pumps can be expected to operate for 20 or 30 years, the recent increases in efficiency and the phaseout of CFC and HCFC refrigerants usually make it more cost effective to replace rather than fix older air conditioners and heat pumps that need significant repairs.
- More information on energy-efficient space
cooling is available at the U.S. Department of Energy's
Web site (http://www.eere.energy.gov/basics/buildings/cooling_systems.html).
- More information on the phaseout of CFC and HCFC refrigerants and on alternative refrigerants is available at the internal Forest Service Web site (http://fsweb.mtdc.wo.fs.fed.us/toolbox/haz/haz23.htm).
Changing the cooling system in existing buildings usually is not cost effective except during a major building renovation. In some cases, use of refrigerated air conditioning systems can be reduced dramatically or eliminated altogether. In climates where hot days normally are followed by cold nights, a system that flushes the building with outside air at night can save all or most of the cost of refrigerated air conditioning. Ground water can be used instead of a refrigeration system to cool air in some places.
Depending on a building's shape and orientation, a cooling tower could be added to the building. Cooling towers use natural convection to draw hot air into the tower, where the air is cooled by the evaporation of water and falls back down the tower into the building.
- More information about how cooling towers work is available in an article at http://www.i4at.org/lib2/aircool.htm.
In very mild climates or during some seasons, opening windows to allow cross breezes can disperse heat from equipment and office activities and keep the inside of the building at an acceptable temperature.
- More information on passive cooling is available in the Sourcebook for Green and Sustainable Building (http://www.greenbuilder.com/sourcebook/PassSolGuide3.html).
Buildings that receive little use during evenings or weekends are prime candidates for programmable thermostats (figure 3). Programmable thermostats can be set to ensure that the heating and air conditioning are reduced when they are not needed. Models can be purchased with override switches so that employees working outside standard hours can enjoy full heating and cooling while they are in the building. These inexpensive devices ($50 to $150 depending on features, plus installation costs) could potentially pay for themselves in as little as 1 month with reduced heating costs and should be installed in nearly every Forest Service building that is heated or cooled.
Figure 3—Programmable
thermostats
are extremely
cost effective energy-saving
devices that
should be used
in nearly
every Forest Service
building that is
heated or
cooled.
Except in areas with extremely high energy costs, it usually is not cost effective to retrofit existing buildings to use solar, wind, geothermal, or other renewable energy sources. Renewable energy may be worth considering in areas where renewable resources are particularly abundant, when grants can be obtained, or when partnerships can be arranged to offset some or all of the initial costs.
- More information about using renewable energy is
available at the U.S. Department of Energy's Energy
Efficiency and Renewable Energy Web site (http://www.eere.energy.gov/).
- Information on possible financial aid for renewable energy projects is available on the Forest Service's internal Web site (http://fsweb.wo.fs.fed.us/eng/facilities/2004_doe_funding.htm).
When appliances and equipment wear out, replace them with energy-efficient models. The ENERGY STAR program is operated jointly by the U.S. Environmental Protection Agency and the U.S. Department of Energy. Among other things, the program develops specifications for low energy use in appliances and equipment, tests appliances and equipment against the specifications, and authorizes use of the ENERGY STAR logo (figure 4) on appliances and equipment that meet the specifications.
Figure 4—The ENERGY
STAR
logo is attached to
equipment
and appliances
that meet
strict
requirements
for
energy-efficient
operation.
The temperature on water heaters can be adjusted by turning the control on the water heater's thermostat. Most thermostats are on the front of the tank, but some are behind an access plate. Energy savings can be from 3 percent to 5 percent for every 10 degrees that the temperature is lowered. Don't turn the temperature down too much, though. Hot water in pipes and tanks should be at least 120 degrees Fahrenheit to prevent growth of bacteria, such as those that cause Legionnaires' disease. Water temperature should be at least 140 degrees Fahrenheit for dishwashing. Some dishwashers come with a preheater so that the temperature on the water heater does not have to be set that high.
If a water heater tank is not well insulated, insulation will pay for itself in about a year. Storage-type water heater tanks that are warm to the touch should be insulated with a precut jacket or blanket, which costs around $10 to $20. Choose a blanket with an insulating value of at least R–8. Some utilities sell blankets at low prices, offer rebates, or install them at low or no cost. Check with your local utility company.
Timers for electric water heaters turn the water heater off at night when hot water isn't needed and/or during your utility's peak demand times, saving 5 to 12 percent on water heating costs. Timers cost $60 or more, but pay for themselves in about a year when they are installed on older water heaters. Timers aren't as cost effective or useful on gas water heaters or on electric water heaters manufactured after 1998 when more insulation and higher efficiency were required.
Consider installing a tankless water heater when the old storage-type water heater wears out. Tankless water heaters don't waste energy keeping water hot. They only heat water when it is needed, and use 25 to 50 percent less energy than tank-type water heaters.
The cost of tankless heaters depends on how much hot water they supply and whether they are gas or electric. Electric heaters cost less to purchase, but are more expensive to operate. Small electric heaters that can supply 2 gallons of water per minute at a temperature 40 degrees Fahrenheit above the supply water can cost as little as $200, plus installation. Tankless gas water heaters powerful enough to supply 5 gallons per minute while raising the water's temperature 60 degrees Fahrenheit could run $1,000 or so, plus installation.
If hot water is needed in distant parts of the building, more than one tankless heater may be needed, but some hot water piping can be eliminated. Complicated installations with several heaters probably will not be cost effective unless the building is being renovated.
Insulating hot water pipes reduces heat loss, raises water temperature 2 to 4 degrees Fahrenheit at the tap, and delivers hot water more quickly, allowing the temperature to be lowered at the water heater. Pipe sleeves made with polyethylene or neoprene foam are the most commonly used insulation, but fiberglass insulation is available also. Tape, wire, or clamp the insulation every foot or two to secure it to the pipe. Keep combustible insulation at least 8 inches from the flue of gas water heaters. Pipe insulation is cheap—less than $1 for a 6-foot length of preformed polyethylene foam insulation for ½-inch diameter pipe—but installing the insulation is fairly labor intensive.
Although most people consider exhaust fans to be a device to control odors, their main benefit is removing moisture-laden air from the inside of a building. Warm, wet air contributes to a number of facility problems, including premature failure of finishes and growth of mold. Sometimes a stove hood or bathroom fan merely recirculates room air after running it through a filter. Recirculating fans don't reduce the moisture in the air. Unless the filters are cleaned or replaced regularly, they don't improve odor problems, either. They just blow air around and use energy. Replace all recirculating fans with exhaust fans.
When selecting an exhaust fan, look for a high volume rating, expressed in cubic feet per minute (cfm) and a low noise rating, expressed in sones. A fan with a rating of 2 sones is twice as loud as a fan with a rating of 1 sone.
An average-sized home bathroom needs a fan that will exhaust at least 100 cubic feet per minute. A fan louder than 1.5 sones may be too annoying to use. Select a fan rated below 1.5 sones, preferably 1.0 sone or less. Fans that meet these requirements cost about $100 at home and electrical supply stores.
To assure that a bathroom fan is used, wire it into the light switch so that the fan goes on when the light is turned on. Usually, fans controlled by manual timer switches are not practical for Government buildings because there's no way to assure that the switches will be turned on.
Standard electric hand dryers in restrooms use a lot of electricity and aren't very effective. Paper towels are expensive and can create a lot of waste in high-use restrooms.
- In high-use restrooms, such as those at visitor centers, consider replacing towel dispensers and older hand dryers with an energy-efficient hand dryer such as the Xcelerator (http://www.exceldryer.com/products/xlerator.asp), the Jet Towel (http://www.mitsubishijettowel.com/), or the AirMax (http://www.worlddryer.com/products/airmax).
These hand dryers are operated by infrared sensors and dry hands completely in just a few seconds. They use up to 80 percent less energy than other hand dryers, making them more cost effective over time than ordinary hand dryers or hand towels, even though their initial cost is about $420 plus installation.
The VendingMiser (figure 5) is a two-part device approved by the Coca-Cola and PepsiCo companies that cuts power to refrigerated soda vending machines during hours when they are not normally used. Automatic sensors mounted at the top of the vending machine are connected to power controllers at the electric outlet that only supply power to the machines when needed to keep drinks cold. The devices "learn" typical vending machine use patterns to help determine when to power up and down. A VendingMiser costs $143.20 for an indoor model and $151.20 for an outdoor model through the General Services Administration (GSA).
Figure 5—VendingMisers (at top of machines and inset) limit power use by vending machines
when no customers are present. The fluorescent
tubes in the door of the Coke machine have
been removed, although you can't tell it by looking at the machine. The lights in the door
of
the Pepsi machine are still in place. The Pepsi machine door does not need to remain lighted
in this bright lunchroom. This photo has
been digitally altered.
The VendingMiser has a payback period of less than 1½ years if electricity costs 7¢ per kilowatt-hour or about 2½ years if electricity costs 4¢ per kilowatt-hour. Similar products are available for glass front coolers, snack machines, and other electrical devices that can be shut down periodically based on use. Some utility companies, States, and municipalities offer rebates of $45 to $120 for installing these products, reducing the payback time.
- More information about the VendingMiser is available at http://www.tufts.edu/tie/tci/pdf/VendingMiserHandout.pdf and http://www.usatech.com/energy_management/index.php.
The lights in vending machine doors are usually
high-output 3-foot-long fluorescent lamps. Disconnecting the
ballast and lamp can save about $20 per year if electricity
costs 4¢ per kilowatt-hour. Door lights are not needed unless
the machine is in an unlit space (see figure 5). Most vending
machines have other lights near the pay slots or lights on the
product choice buttons to let people know the machine is in
operation. A few machines may need a small sign to reassure
customers that the machines are operating.
