Occupancy Patterns and Peak Coincidence
Key Energy Uses and Equipment
Performance Requirements and Flexibility
Typical Demand-Response Strategies
Hospitals can participate in commercial and industrial (C&I) demand-response (DR) programs without adversely affecting their critical loads, which include medical equipment. Hospitals are generally large facilities offering around-the-clock operation and significant load shedding potential, which makes them good candidates for DR programs. Because the hospital industry tends to be underfunded, hospitals are primarily motivated by the financial incentives offered through DR program participation. They can earn incentives by shifting load to their robust backup generators and by cutting back on noncritical loads, such as cafeteria and lounge lighting.
Hospitals are also good candidates because they’re required to routinely test their backup generation. Unlike other C&I sectors, hospitals are not afraid to run backup generators during DR events. Testing backup generation typically occurs at night, but once enrolled in a DR program, hospitals can reschedule their tests to coincide with DR events. Hospitals typically have multiple backup generators with large capacities—up to 2 megawatts per generator.
Most healthcare facilities are active 24 hours per day. On hot summer afternoons, hospital cooling loads and lighting systems will be operating at full capacity and will coincide with utility peaks. As a result, a hospital will typically be able to reduce loads by 10 to 15 percent during DR events. This reduction could be even larger if the hospital uses its backup generator to shift loads off the grid.
Hospitals are large buildings with many energy-intensive operations. The largest electricity loads in hospitals are, in decreasing order: lighting, ventilation, and cooling—making lighting and HVAC the best targets for DR. Hospitals often have special-purpose rooms such as cafeterias and lounges, in which facility operators can curtail lighting and plug loads without interrupting routine operations. About one-quarter of all hospitals in the U.S. also have a building automation system (BAS) that monitors and controls HVAC and lighting systems. Lastly, all hospitals are required to have backup generation, which facility operators could dispatch during events.
A large hospital in Connecticut achieved a noticeable load reduction by participating in a DR program. From noon to 6:00 p.m., the facility operators increased thermostat setpoints, turned off half of the lights in common areas, shut down escalators, and dispatched backup generation (Figure 1).
Hospitals have to pay close attention to indoor air quality. Hospital patients may have weakened immune systems, which can make them sensitive to poor air quality. Healthcare employees are also at increased risk of contracting an airborne disease if air quality isn’t properly maintained.
Hospitals maintain indoor air quality primarily by ensuring adequate ventilation and controlling humidity. Hospitals must therefore be careful when using strategies that could reduce ventilation and increase humidity.
Hospitals can successfully contribute to load reductions using a number of proven strategies. These focus on lighting, cooling, load shifting, BASs, and backup generation.
Curtailing lighting. Facility operators can curtail lighting in special-purpose rooms, such as cafeterias and lounges, when they are unoccupied. Operators can also reduce lighting in corridors. Rooms and corridors can use natural lighting if available. On average, reducing lighting loads in common areas, such cafeterias and lounges, can reduce a building’s peak load by up to 5 percent (Table 1).
Setting back chillers. Setting the thermostat back can significantly decrease demand for cooling. In many cases, facility operators can raise temperature setpoints on chillers and slow pump systems while still providing adequate cooling. This strategy must be used carefully because other equipment within the chilled-water system may begin to work harder to compensate for the chiller’s higher setpoint. Increasing setpoints by 5° Fahrenheit in hospitals can typically reduce overall peak load by 10 to 15 percent.
Shifting loads off peak. Hospitals can shift certain processes to before or after a DR event. For example, facility operators can schedule food preparation, dishwashing, and laundry around a DR event. This strategy requires that hospital management effectively communicate scheduling requirements to staff so that they don’t mistakenly turn on these loads during a DR event.
Using a building automation system. Many modern healthcare facilities have complex BASs that use sensors and controllers to monitor and optimize lighting, temperature, humidity, and indoor air quality while minimizing lighting and HVAC energy use. If the BAS can communicate directly with the DR facilitator, the BAS can automatically adjust thermostat setpoints and reduce discretionary lighting loads upon DR notification—eliminating the need to manually adjust equipment. If a hospital doesn’t have an automatic DR system, the staff or a facility manager would need to manually switch the BAS into DR mode to reduce HVAC and lighting loads through the BAS.
Switching to on-site generation. All hospitals have large and robust on-site backup generation systems. This makes these customers great candidates for DR programs that allow load shifting onto these generation sources. Switching to backup generation is usually immediate, so it causes no interruptions to service. However, because backup generation typically consists of diesel generators, local or state air-quality regulations may limit this method of curtailment.
Berkshire Health Systems (BHS) is a private, nonprofit hospital that operates three separate facilities in Berkshire County, Massachusetts. In 2006, BHS enrolled in a DR program for two reasons. First, the hospital saw the DR program as a revenue-generating opportunity. Second, as part of the program, the hospital is able to test its backup generation system while receiving incentives for doing so. As an accredited healthcare facility, BHS is required to routinely test and maintain its backup generators.
BHS participates in EnerNOC’s DR program, which is offered through Western Massachusetts Electric. During a DR event, EnerNOC notifies facility engineers at each of the three facilities via phone and e-mail. The facility managers then use a BAS to reduce loads in their facilities. For example, the facility managers typically reduce lighting loads, increase thermostat setpoints, and shut down a portion of the elevators.
BHS also operates its backup generation system during DR events—each facility has two generators. During each event, BHS is able to reduce load by 1.3 megawatts without affecting any of the hospital’s critical loads. As with all medical facilities, the primary responsibility of BHS is to maintain the comfort and safety of its patients and staff, so the organization must be careful when reducing loads.
Each year, BHS receives $25,000 in DR incentive payments for participating in the program. These payments are used to maintain operations at the healthcare facilities and to finance projects aimed at improving the energy efficiency of the facilities.
Managing Energy Costs in Hospitals, E Source Business Energy Advisor