Once your energy management program has demonstrated success with the items above, you’re ready for measures that require financial investment and detailed planning.
Tune Up Building Systems and O&M Programs
Track your energy use. Use the Energy Star Program’s Portfolio Manager to track your buildings’ energy consumption (if you need help, Energy Star has created a site specifically for multifamily housing). Once you’ve entered basic data such as building floor area and utility bill data, this tool calculates an index of energy consumption per square foot that will enable you to compare individual buildings, either across your portfolio or against their past performance. Armed with such comparisons, you can identify and prioritize the buildings with the biggest energy consumption problems, or track your progress for those buildings in which you’ve implemented energy-efficiency measures.
Upgrade your operations and maintenance (O&M) program. One simple way to improve the energy efficiency of buildings with little or no capital investment is to ensure that the building shell—and the expensive systems within it—are properly operated and maintained. Implementing a rigorous O&M program requires the buy-in of senior management and O&M staff alike. Ensuring that O&M activities are thoroughly documented and that staff are well-trained and -equipped also helps. The U.S. Department of Housing and Urban Development (HUD) published a workbook (PDF) that contains O&M checklists as well as suggestions for numerous other O&M measures.
Commission your building. According to the Building Commissioning Association, commissioning is a systematic process for investigating, analyzing, and optimizing the performance of building systems by improving O&M procedures to ensure continued performance over time. Even for smaller buildings, according to a Lawrence Berkeley National Laboratory (LBNL) study, simple payback periods were usually less than 5 years, and frequently less than 10 years. LBNL found that most commissioning activities yielded simple payback periods of less than 3 years. Retrocommissioning can guide you through the process and help you decide whether commissioning is right for your building.
Take Control of Lighting and Temperature
Replace incandescent bulbs with compact fluorescents. Lighting typically offers some the most rapid simple payback periods of any energy-efficiency upgrade—often less than three years. Compact fluorescent lamps (CFLs) consume about one-third to one-quarter of the energy consumed by incandescent bulbs, put out less waste heat to be removed by the air-conditioning system, and require less maintenance because they typically last 10 times longer than incandescent bulbs.
Install lighting controls. Install timers in areas where occupancy is predictable and occupancy sensors where it’s not. See Lighting Controls for additional efficiency ideas. Install two-level lighting—which lowers light levels during low-usage times, when less light is sufficient—for corridors, stairways, or other areas that need to have the lights on 24/7. Check with building codes to determine what areas require 24-hour lighting.
Install programmable thermostats. Lower the temperature settings in common areas during times of little or no use. Setting temperatures back by 10° to 15°F for eight hours per night may reduce heating costs by 10 percent, according to Energy Star. HUD estimates that renters with dedicated heating and cooling systems can save about $180 a year by properly setting and maintaining programmable thermostats.
Install New Equipment or Replace Old Equipment
Reduce pool losses. Install a pump timer so that the pool pump does not run during times of low usage. Purchase a pool cover to help maintain pool temperature and achieve energy savings of 50 to 70 percent, according to the DOE. For indoor pools, reduce energy costs by installing a humidistat to control the pool exhaust fan so that it does not run continuously.
Upgrade HVAC equipment upon replacement. Prepare for replacement of failed HVAC equipment now. Contact suppliers and ask them to recommend high-efficiency replacements for aging equipment so that when the time comes you can quickly specify the equipment you want. New cooling equipment sometimes may be sized smaller than the original equipment if efficiency measures have reduced energy consumption and heat loads. Retain an engineer to do sizing calculations. Document the specifications for replacement equipment so that they can be readily accessed and updated every few years.
Upgrade water heaters upon replacement. Plan for water heater replacements as you would the replacement of HVAC equipment. For multiunit systems with gas heating, upgrade to condensing water heaters, which can reduce water heating bills by about 30 percent, according to the DOE. For single-unit installations, a tankless water heater might be a good way to go. Where electric water heating is used, under some circumstances, a heat pump water heater can cut energy consumption in half. Energy Star maintains a list of high-efficiency products, including a variety of water heater types; it also provides estimates of how much you can save with Energy Star–qualified products.
Replace old appliances with Energy Star appliances. An Energy Star refrigerator uses at least 20 percent less energy than required by current federal standards and 40 percent less than a conventional 2001 model. An Energy Star clothes washer can reduce energy costs by more than a third and water costs by more than half. An Energy Star–rated dishwasher uses at least 41 percent less energy than conventional dishwashers. Energy Star has created calculators to help you estimate how much an Energy Star product can save you.
Reduce hot water demand. Low-flow showerheads and aerator faucets can be placed both in common areas and in individual units to reduce the flow of hot water and, thereby, the demand on water heaters. According to the DOE, low-flow showerheads can be purchased for $10 to $20 apiece and can achieve water savings of 25 to 60 percent.
Take control of hot water recirculation loops. Install controls on recirculation pumps so that they don’t run continuously—heating water and electricity for running the pump all the time can waste copious amounts of energy. Temperature-controlled systems are better, although systems that measure the water temperature at the return to the water heater can be improved by moving the sensor to the last riser (Figure 3). After all, there’s nothing to be gained by keeping the return pipe after the last riser warm. Insulate the recirculation loop to minimize losses and keep the pump off longer. And even more energy waste can be eliminated by installing demand controls, which ensure that the recirculation pump only runs when hot water is needed. Signal demand at major hot water system end-points with buttons, motion sensors, or flow switches, and mount a temperature sensor at the last riser to turn off the pump.
Figure 3: Controlling recirculation pumps
Where recirculation loops are controlled by temperature, the sensor is frequently located right near the pump and backflow preventer, where water is returned to the water heater. A better way to control such loops is to locate the temperature sensor right near the apartment supply line that is farthest from the water heater. Such a location will enable the pump to turn off when heated water reaches the sensor location, and allow the portion of the recirculating loop that doesn’t serve any supply lines to remain relatively cool. Insulate the heated portion of the recirculation loop so that it stays warm longer after the pump has shut off.
Replace exit signs. According to current U.S. federal standards, all exit signs manufactured after January 1, 2006, must draw no more than 5 watts per illuminated face of the sign. To see what your building could save by replacing aging exit signs with contemporary models, use the Energy Star exit signs savings calculator.
Get Tenants Involved
Make green leases. Green leases provide a vehicle by which building owners can invest in efficiency improvements in tenant space and recoup the costs by raising the rent in the middle of the term. For example, assume a building owner invested in an efficiency upgrade that reduced a tenant’s utility bill by $20 per month. The manager could then increase the rent by $18 per month, recovering $216 a year to pay for the investment. The tenant would enjoy both a small reduction in overall costs as well as any additional amenities provided by the upgraded property. So far, green leases are used more frequently in commercial properties than residential properties due to their complexity.
Meter individual units. According to the New York State Energy Research and Development Authority’s (NYSERDA’s) Residential Electrical Submetering Manual (PDF), submetering saves energy and the savings persist over time. Furthermore, the manual makes the case that submetering benefits 60 to 70 percent of residents and is “eminently fair and ultimately benefits building owners.” Installation costs for typical submeters (such as the one shown in Figure 4) can range from $150 to $700 per unit, depending on the meter selected and how and where it is installed. According to NYSERDA, electricity consumption usually drops by about 10 to about 20 percent when master-metered buildings are converted to individual submeters. Electronic meters combined with wireless communication make it feasible to retrofit such meters into a wide variety of buildings.
Figure 4: Submeters empower tenants to manage their energy costs
This submeter, manufactured by E-Mon D-Mon, is typical of many such products suitable for installation in multifamily buildings. Such submeters can be retrofitted into existing buildings using a wireless mesh communication network.
Some tenants have resisted submetering, especially when their units were retroactively converted. One way to minimize such resistance would be to employ green leases that would enable managers and tenants alike to improve both building shell and energy consuming equipment in conjunction with the submetering implementation.