Most of these are low-rise structures of medium size with a central core area for offices and administration and wing type construction for classrooms. There is usually a small gym with little or no seating. Depending on the immediate growth in the area there may also be a number of classroom trailers required prior to and during construction of school additions. Teaching approaches keep changing, going from individual classrooms to open-plan layouts and back again. Open-plan schools have portable partitions that are changed frequently. The HVAC system design must be flexible to accommodate these changes.

The key building energy systems electrical loads are lighting, and HVAC systems. Cafeteria loads - cooking, ventilation, lighting and even water heating - can be significant in some areas depending on availability of natural gas. With the advent of computers, office equipment is a rapidly increasing load - especially in student computer labs. However, most of the electricity is consumed in the lighting and cooling systems. Some of the key issues to consider in building energy use are in the school building's:

• Construction materials, amount of glass areas, insulation, and orientation to the sun
• Occupant use and maximum occupancy characteristics (especially time of day),
• Lighting levels and lamp source efficiency (which affects the cooling and heating loads),
• The time and seasonal vale of fuel and power use in building design alternatives,
• Floor loadings for office equipment and specialized lighting,
• Availability and price of water for potential cooling system use.

Most school designs are similar except for kindergarten to fourth grade where warm floors may be required. HVAC equipment should be simple to operate and require no skilled personnel.

Schools are typically designed for a long life under difficult occupancy conditions and tend to be of high quality construction. Due to funding with scarce tax dollars and via bond issues, the desire for amenities that are visible predominates. Energy conservation and recovery concepts that raise the first cost but lower O & M and life cycle costs are difficult to justify during original construction. However, energy retrofits for the lighting and HVAC systems have successfully been promoted with some of the savings going toward amenity improvements - e.g. a school might get new lights and new blackboards with funding from the lighting cost savings.

HVAC

The HVAC systems will vary widely, largely dependent on the size, age of the school and geographical location. In past years, ventilation only dominated, however new schools are largely air conditioned. The current trend is to use central or rooftop systems for administration and common areas and PTAC or geothermal heat pumps with individual control for the classrooms. In climates with low heating loads, electric resistance heating is often used for the primary or secondary (for heat pumps) heating source. This design also maximizes scheduling flexibility for the off peak uses required for PTA meetings, parent/teacher conferences and other school meetings.

The gymnasium and cafeteria usually require their own separate systems because of their unique loading characteristics. The cafeteria may have heat pump water heaters or heat recovery water heaters included in their systems.

Proper ventilation is necessary to control odors and avoid "sick building" syndrome. Provision should be made to shut outdoor air dampers when individual zones or rooms are unoccupied. Many areas have stringent codes covering fire, smoke, building design, ventilation, and noise control. In many cases, noise production and protection from vandalism must be considered.

Recommendations/Energy Services Opportunities

Energy conservation concepts must be simple: cooling interior spaces with outdoor air using economizer cycles, night setback in individual areas, and outdoor air damper control during system shutdown at night and other such times. Water-loop heat pump systems may also conserve energy if the building has significant interior zones. It may be possible to justify conversion to higher efficiency equipment or even a complete redesign to geothermal heat pumps as existing HVAC equipment ages and must be replaced. Some of these designs combine thermal storage where excess heat generated during the day is stored and used for heating.

Water Heating

Service water heating in these schools is needed for janitorial work, lavatories, cafeterias and occasionally for shower rooms and swimming pools. Water heating for cafeterias, shower rooms and swimming pools are usually on their own individual systems due to loading and temperature characteristics. Hot water used in cafeterias is about 70% of that usually required in a commercial restaurant serving adults and can be estimated by the method used for restaurants. Where NSF sizing is required, follow Standard 5.

Provision may be required to supply 180°F sanitizing rinse depending on the type chemicals used in the dishwashing systems. If this is required, a booster heater must be sized according to the temperature of the supply water - usually 140°F - and the required flow of the dishwasher.

A separate water heating system for swimming pools can be sized as outlined in the section on Swimming Pools\Fitness Clubs.

Recommendations/Energy Services Opportunities

Predominate energy conservation measures with water heating will be to supplement cafeteria water heaters with either heat pump water heaters - located in the cooking area - or heat recovery water heaters attached to the refrigeration systems. If a central water heater is used for laboratories then point of use water heaters will also provide good payback. Refer to the water heating section for more detailed assistance.

Cooking

Food service in schools typically serve food in Cafeteria style to be consumed by students and teachers who take their trays to indoor or outdoor tables. Pre-planned meals with menus published in advance is becoming more prevalent.

Recommendations/Energy Services Opportunities

The predominate energy source for school food service has trended toward natural gas. However, some school systems are realizing the overall benefit of electric cooking due to ventilation reductions and personal comfort to the cafeteria staff. Refer to the food services sections for assistance with electric cooking options

Lighting

Most of the dedicated space in schools are classrooms. A typical classroom design will accommodate class sizes up to as many as thirty students. There will usually be a blackboard or whiteboard on one or more walls. There may be windows to provide natural light to the room.

In elementary schools, students spend most of their day in the classroom, writing and reading. Adequate light levels of 50 to 100 footcandles are needed for both the horizontal work surface and the vertical plane of the blackboard. Schools often set the standards for the minimum acceptable horizontal footcandles in a classroom.

Today, many classrooms no longer have desks set in rows. Instead, they'll have flexible seating around tables or they have areas of the room set aside for activities. This means that today's classrooms require a flexible lighting system that doesn't dictate the placement of desks.

Recommendations/Energy Services Opportunities

Classrooms for special purposes like sewing, art or shop may require special task lighting. Provide uniform light levels and use lamp sources with 3500 to 4100K color temperatures and at least 70 CRI. T-8 Fluorescent lamps, especially triphosphor types, are an ideal choice.

Classrooms with high ceilings are good candidates for a suspended direct/indirect combination fluorescent fixtures, significantly reducing glare on work surfaces. Lower ceilings will require either surface mount or recessed fixtures. Recessed fixtures may be better in this situation because they're less obstructive. If the classroom is a computer lab, then use high VCP fluorescent fixtures to ensure good glare control. Provide flexible switching, such as partial fixtures or partial lamps per fixture. This allows for lower light levels during the showing of films or while using other audio/visual equipment.

Predominate lighting efficiency upgrade opportunities will be from T-12 to T-8 Fluorescent and incandescent to LED exist signs. Older gymnasiums may be lighted with incandescent or mercury vapor and thus offer upgrade potential to pulse-start metal halide. Conversion to the pulse-start metal halide can also be justified for some older metal halide systems.

Other Information

The trend in school electrical system designs is to place a new service and utility meter at each addition. The original school likely had at least two meters - one for the school and one for the gymnasium. It may be in the school's best interest to use a primary meter to reduce electric cost.

Recommendations/Energy Services Opportunities

Energy Management systems (EMS), especially direct digital control (DDC) systems, can be most beneficial for scheduling before and after hour events. Traditionally, HVAC systems are left running or were not available at all for special events. Lighting systems may be left on overnight as a special interest group has their meeting and walks away without switching things off. Simple EMS systems can be located in the school maintenance and/or administration office where lights and HVAC needs can be scheduled and controlled.