These buildings are used to store merchandise, equipment and material inventories. Some may be open to the public. Others are part of an industrial facility.
Powered forklifts and trucks using batteries or gasoline, propane and other fuels are often used. Proper ventilation is needed to prevent the buildup of carbon monoxide (CO) and other noxious fumes. Electrically powered forklifts must have properly ventilated battery-charging rooms.
HVAC
They are usually not cooled but are provided with sufficient heat and ventilation to provide a tolerable working environment. Warehouse temperatures are kept above 40°F to protect sprinkler and water piping and stored material from freezing. Radiant or forced flow unit heaters can be used and are usually located near the loading doors and work areas.
In summer, adequate ventilation with noticeable air movement is used. Some use roof spray cooling to keep areas under the roof from becoming too hot and spoiling the stored items. Where storage conditions require mechanical cooling, internal loads from lighting, people and other sources is usually low. Most of the load comes from transmission and infiltration. The load profile will be relatively flat if the warehouse is full.
In some climates mechanical dehumidification systems must be provided to control mildew formation. These systems convert latent heat to sensible heat to keep indoor humidity under control. Moisture should be removed at the highest concentration - from the outdoor air before mixing with return air. Reverse cycle units can also preheat makeup air in winter.
Typical System
Offices for shipping, receiving and inventory control are usually air conditioned with air-cooled unitary systems or heat pumps. Special purpose mechanical dehumidifier systems or desiccant systems are used where warehouse humidity control is a factor.
Recommendations/Energy Services Opportunities
There may be opportunities for a central control system for fire, smoke and security, maintenance control and operations, and energy management. Other opportunities include:
- If stored materials create odors, add odor control (carbon filters and controlled recirculation) to reduce fresh air intake.
- Older inefficient systems should be investigated for upgrading or replacement, particularly if CFC refrigerants are used.
- Electric desiccant heat pump systems are excellent for places requiring humidity control and not necessarily temperature control.
Water Heating
Hot water is used for cleanup, employee locker room showers, and rest rooms. Hot water consumption varies significantly among individual facilities.
Typical System
Most water heating is done separately from the building heating system using direct resistance or gas heaters, and in some cases, point-of-use heaters.
Recommendations/Energy Services Opportunities
If existing water heating systems are inefficient or inadequate, replace with modern efficient equipment. Also add better insulation on storage tanks, or timer controls. Instantaneous electric water heaters should be considered whenever the only hot water uses are in the restrooms.
Lighting
Lighting usually accounts for 50% or more of the electrical load in a warehouse. Lighting layout should be dictated by stored material layout and material-handling techniques deployed in the building, but most frequently are positioned in a symmetrical grid since many were built as speculative buildings. The current trend is to use metal halide lamps with parabolic reflectors, however, a number of fluorescent, high pressure sodium, mercury vapor, and even incandescent spotlights can be found.
Many warehouses have isolated activity on any given day where orders are being pulled from specific areas. Some areas may be occupied the entire day, while others may be occupied only a few minutes. Very little light may be required where automatic retrieval systems are used. Color may or may not be important depending of inspection requirements and handling techniques.
Task lighting or at least more lighting may be required in some areas for parts assembly, packaging, or other special requirements.
Recommendations/Energy Services Opportunities
The three best lighting opportunities are with redesign, high efficiency lighting, and controls. It may be possible to significantly reduce the number of fixtures in a facility if the original grid layout does not match the stored product layout - look for fixtures directly over shelves or obstructed by handling equipment. Existing lighting should be replaced with rapid start metal halide and/or T-8 fluorescent lighting - the metal halide is slightly more efficient, but the fluorescent has lower maintenance cost. Each isle or product grouping should be separately controlled with motion sensors or at least wall switches - this would allow significant lighting use reductions in lightly traveled areas.