Hospitals and medical centers generally fall into one of two categories -- For Profit or Not-For-Profit. In terms of energy projects, there are significant differences: Hospitals are large users of both electrical and thermal energy on a continuous basis. Their operation is year-round and 24-hours per day. The electrical loads are largely lighting, HVAC, elevators, special equipment (CAT Scan, MRI, etc.), and floor loads of computers, copiers and the like. Backup on-site generation is required for essential services. Thermal loads tend to be dominated by the HVAC system as indicated in this pie chart. A laundry represents about 10% of the thermal load ...or adds about 11%. If there is no laundry on the premises, the HVAC use rises to almost 88%. Sterilization can be a major thermal user - either electrically or natural gas - depending on the number of rack washers and autoclaves. Past trends were towards steam heated systems, but newer systems are frequently direct fired. | ||||
HVAC | ||||
Hospital air conditioning assumes a more important role than just the promotion of comfort. In many cases, proper air conditioning is a factor in patient therapy; in some instances, it is the major treatment. The application of air conditioning to health facilities presents many problems not encountered in the usual comfort conditioning system.
The basic differences between hospitals and other buildings are:
There are seven principal divisions of an acute care general hospital: 1. surgery and critical care, The environmental requirements of each of the departments/spaces within these divisions differ to some degree according to their function and the procedures carried out. Typical SystemDue to the wide variations in the HVAC requirements of the different divisions, most mechanical cooling systems in medium and large hospitals are indirect, using steam boilers and a centralized chilled/hot water distribution to the various air handlers serving the different departments. These chillers and the boilers may be located in one central plant, in individual buildings, or a combination of the two in older facilities that have gone through numerous expansions; hospitals that have grown over time may have several mechanical rooms located in different buildings. The hot and chilled water piping may or may not be interconnected. Special areas, such as the operating suite, may or may not be served by separate systems. The number and size of boilers and chillers should provide reserve capacity. The typical design objective is "largest unit out of service." The remaining units should be able to meet the peak loads. In some cases, hospitals will also want to diversify their energy use, possibly using gas cooling equipment for emergency cooling service (since this also reduces the size of the required emergency generators). One alternatives is obviously thermal storage to produce the same benefit, while also permitting colder than normal water temperatures which have proven popular in operating room designs. These choices require careful evaluation. Indoor air quality is an important issue. Health care facilities are designed according to strict state and/or local agency guidelines to maintain a controlled environment to provide comfort, a healing therapy, and to minimizing the spread of infectious diseases. Systems must provide air virtually free of dust, dirt, odor, and chemical and radioactive pollutants. If outdoor air intakes are properly located, and areas adjacent to outdoor air intakes are properly maintained, outdoor air, in comparison to room air, is virtually free of bacteria and viruses. Infection control problems frequently involve a bacterial or viral source within the hospital. Ventilation air dilutes the viral and bacterial contamination within a hospital. If ventilation and their filter systems are properly designed, constructed, and maintained to preserve the correct pressure relations between functional areas, they remove airborne infectious agents from the hospital environment. Surgical suites usually only operate a portion of each day, and typically use 100% outdoor air with 15 or more air changes per hour. Surgeons prefer very cool space temperatures for comfort and to reduce microorganisms. These areas could be served by a separate chiller system coupled with ice storage. Air-cooled condensing is often used to avoid the operation and maintenance of a separate cooling tower. Recommendations/Energy Services OpportunitiesHealth care is an energy-intensive, energy-dependent enterprise. Hospital facilities are different in that they operate 24 hours a day year-round, require sophisticated backup systems in case of utility shutdowns, use large quantities of outside air to combat odors and dilute microorganisms, and must deal with problems of infection and solid waste disposal. Similarly, large quantities of energy are required to power diagnostic, therapeutic, and monitoring equipment and support services such as food storage, preparation, and service and laundry facilities. Hospitals are always looking at ways to cut costs. High efficiency lighting, thermal storage, energy management systems, heat pipes, desiccant systems, run-around loops, economizer cycles, "free cooling", and other forms of heat recovery and energy conservation are receiving increased attention to reduce energy bills. Energy costs can also be reduced in 100% outside air areas by using desiccants and/or heat pipes, run-around coils, VAV systems, load shedding, and systems to minimize ventilation in unoccupied areas. With such a large amount of thermal energy consumed in the HVAC, Food Service and Laundry segments, there are often many opportunities for you to assist the hospital operating staff in identifying and implementing them. In many cases, performing an energy audit is in order. Additionally, here are a group of other opportunity areas: Boiler Room:
Chiller Plant:
HVAC:
Other:
Laundry:
Kitchen:
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Water Heating | ||||
Domestic hot water needs are included in the several segments using it; and can amount to a total of 5% of thermal energy use. Typically about half of a hospitals water consumption is heated. Daily consumption of hot water can be quite varied depending on the type hospital, its size, and the occupancy factor. Available data indicates daily consumption ranging from 25 to 90 gallons per bed, with the maximum hours consumption ranging from 7 to 22 gallons per hour-bed. Water temperature requirements range from not to exceed 120°F for clinical uses (shower and bathing facilities), to 120°F for most dietary uses with booster heating where needed, and at 140°F for most laundry procedures, again with booster heating where needed Typical SystemAs steam is used in hospitals for heating, dietary and sterilization purposes, it is typically also used for service water heating. Often steam-to-hot-water heat exchangers and storage tanks are strategically located in various areas using large amounts of hot water (kitchens, laundries, etc.). In addition to lavatory uses, hot water uses include service sinks, general cleaning, and hydrotherapy. Recommendations/Energy Services OpportunitiesThese include:
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Cooking | ||||
Typical SystemMany hospitals contain cafeterias, restaurants or fast food operations.Their cooking needs should be handled as appropriate. | ||||
Lighting | ||||
The instrument and supply room lighting should be 20 to 50 footcandles. Surgical task lights with good color rendering over the work area are typical. The color temperature should be 4100k with a CRI of at least 80. Specially-designed surgical task fixtures usually use halogen sources. The fixtures should have multiple lamps to prevent total lamp failure. Surgical general lighting should also reduce brightness extremes between the operating area and the rest of the room. The color temperature of the general lighting should match the task lighting. Recessed 2 X 4 fluorescent fixtures with tri-phosphor lamps are a good choice for the general lighting. Be sure to avoid glare from reflections on patient monitors. With fluorescent fixtures in a surgical suite, take special precautions to reduce electromagnetic interference. The interference could affect electronic life support systems. Fixtures may need to have welded construction, special lenses and radio frequency filters. Examination/Patient Rooms
Adjustable examination lights can meet the visual performance needs of medical professionals. The exam lights should provide 50 to 100 footcandles. Choose lamp sources with a color temperature from 3500k to 4100k and at least 80 CRI. Both incandescent and triphosphor fluorescent lamps are good choices. Incandescent downlight fixtures with wall switch controls, perhaps dimmer controls, are good for general lighting - even with higher maintenance cost due to lower rated burn hours. A fluorescent fixture mounted on the wall above the bed is ideal for patient reading. This fixture should have a switch for the patient. Perimeter indirect or cove fluorescent lighting can wash the walls providing a spacious and soft lighting effect. A night light, with a switch at the bed and on the wall, is a good idea. A flush wall-mounted fixture is best. One that illuminates the floor enough to move about the room, but won't disturb the patient or cause glare. Recommendations/Energy Services OpportunitiesMany older hospital still have incandescent exit signs and even if they have upgraded to fluorescent can justify LED signs. Most fluorescent lighting is probably the old T-12 technology and should be replaced with T-8 lamps and magnetic ballast. Caution does need to be exercised with the ballast, however, because of potential problems with very sensitive hospital equipment - most lighting suppliers know how to handle this issue.Parking lot, security and façade lighting may still have incandescent and mercury vapor lighting systems. Metal halides or high pressure sodium should be considered as replacements. | ||||
Refrigeration | ||||
Typical SystemMany hospitals contain cafeterias, restaurants or fast food operations, as well as morgues and other facilities requiring mechanical refrigeration. Their refrigeration needs should be handled as appropriate. Recommendations/Energy Services Opportunities
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Traditionally, the objective of lighting for surgical suites and other critical care units is to provide high illumination levels for the medical team. The ability to perceive color, fine detail and work with small instruments is essential. Visual tasks include continuously reviewing a variety of patient monitors and a range of three-dimensional procedures. Task light levels should be at least 2500 footcandles and the general lighting should be 100 to 200 footcandles.
Used nearly 24 hours a day, these spaces serve as bedroom, examination and treatment room. Lighting to satisfy all these requirements is complex. General lighting should be low and residential, about 5 to 10 footcandles. There should also be sufficient illumination available for patients to read, take meals and move about their area, 20 to 50 footcandles.