Dormitories are domiciliary facilities usually associated with an educational facility such as an academy, school, college, or university. In addition to the student rooms or suites, these buildings commonly have large dining and kitchen facilities, laundry, computer and study areas, administrative offices, and common areas for recreation. They often are multi-story buildings, some being high-rises in downtown city campuses.
The typical energy systems in dorms include HVAC, lighting, electrical, including wiring for data cabling and cable TV, control system, and plumbing.
As the trend is to increase year-round usage, most new dormitories include air conditioning, while many pre-existing ones do not. Dormitories vary in design; some may include individual or double-occupancy student rooms with common bathrooms for each floor, while others consist of suites that contain a small living/dining area, kitchen, bathroom, and two (2) or more bedrooms.
Student room systems for these facilities range from individual room units (PTACs, PTHPs, and water-loop heat pump units), to a central chilled/hot water plant that serves individual room fan-coil units, to main campus plants that supply chilled water, steam, or hot water. Units can be located in the outer wall, ceiling over the vestibule, or vertically in the wall between rooms. Each room must be supplied with outdoor air to meet IAQ standards and local codes (typically about 30 cfm). In some climates, baths have supplementary heat. All systems must be low-maintenance and easily repaired. In more northern climates where air conditioning is not included, baseboard radiation or radiant panel systems have been successfully used.
The dining and kitchen facilities, laundry, computer and study areas, administrative offices, and common areas for recreation should be separately zoned and independently controlled, but can share common heating and cooling plants. These load variabilities increase the feasibility of water loop or geothermal heat pump systems, particularly on campuses with year-round activity. In addition, the heating plant must include provisions to prevent freezing during winter breaks or emergency shutdown.
Energy Saving Recommendations
- Most older dormitories did not have air conditioning included when they were first built. Some do not include a separate ventilation system and use bath and kitchen exhausts instead, plus opening and closing of windows for ventilation. In some, unsightly, individual window units have been installed; most of these are old and are candidates for replacement.
- Older, inefficient systems should be investigated for upgrading or replacement, particularly if CFC refrigerants are used.
- Renovate older buildings with modern heating and/or cooling systems. Where budgets are tight, consider through-the-wall packaged terminal or heat pump units; they are self-contained and do not require extensive piping and ductwork.
- Retrofit with heat reclaim coils or air-to-air heat recovery devices. Such recovery devices can reduce energy consumption by transferring 40 to 80 percent of the sensible and latent heat between the exhaust air and supply air streams.
- Retrofit a "free cooling" heat exchanger in a tower/chilled water plant system.
- In large dorms, energy management systems with a central panel may allow individual air-conditioning systems or units to be monitored for maintenance and operating purposes.
Hot water requirements for college dormitories generally include showers, restrooms, service sinks, and washing machines and dryers. But peak demand usually results from the use of showers. Load profiles and hourly consumption data indicates that peaks may last one (1) or two (2) hours and then taper off substantially. Peaks occur predominantly in the evening, around midnight.
Where applicable, include hot water used for food service and other such tasks. Where suites are involved, be sure to include their usage of food preparation equipment and dishwashing.
Most water heating is done separately from the main building heating system and uses direct resistance or gas heaters; in some cases, point-of-use heaters.
In more northern climates, you will often find a semi-instantaneous heat exchanger operating from the boiler hot water system, which tends to eliminate the standby losses of storage water heaters and tanks. Storage water heaters and tanks supply hot water at 120°F which reduces the potential for scalding, but increases the potential for bacteria formation in any stagnant storage volume. However, a semi-instantaneous heat exchanger system eliminates this stagnation possibility of low temperature hot water (under 140°F) and prevents colonies of bacteria from developing. Use of a combined space and hot water heating system such as this must meet the provisions of ASHRAE Standard 100.5: typically multiple high efficiency boiler modules are used, with one boiler module about equal to the service water heating load.
Energy Saving Recommendations
If existing water heating systems are inefficient or inadequate, replace with modern, efficient equipment. You can also add better insulation on storage tanks or timer controls. The ASHRAE Applications Handbook chapter on Service Water Heating analyzes typical hot water use data as well as estimating procedures.
Dorm rooms are typically used for both sleep and study. So for general illumination, use a ceiling mounted incandescent or fluorescent fixture and be sure to provide a low level, from 5 to 20 footcandles.
Designated study areas require added task lighting to give 30 to 50 footcandles. Try to place the task lighting so that one student can sleep while the other studies. If there are built-in desks, then use fluorescent task lighting under overhead shelves or cabinets. Be sure to shield the task lamp from the direct view of someone seated at the desk or laying in bed.
Energy Saving Recommendations
The existing lighting systems in dormitories are likely a combination of incandescent and T-12 Fluorescent. For maximum energy-saving efficiency, the T-12 lamps and magnetic ballast should be replaced with T-8 lamps and electronic ballast. In general, the incandescent lamps should be replaced with compact fluorescent ones; however, these lamps have a tendency to "walk off" at the end of a semester, so locking-type compacts are recommended. Where compact fluorescent lamps cannot be installed into ceiling- or wall-mounted incandescent fixtures, a complete fixture/lamp replacement may be justified.