Tips for reducing your air conditioning usage.

As the thermometer climbs toward triple digits, air conditioners work hard to keep the indoor temperature tolerable. The cost of comfort is often higher electricity usage. So what can you do to keep your cool and keep costs down?

Close the door

Growing up, we were often reminded to close the door to keep the heat in during winter, the cold in during summer, and the bugs out during the spring. Well, that was good advice. One of the biggest loads on an air conditioner is infiltration — the introduction or leakage of outdoor air into a conditioned space. That outdoor air has to be cooled and dried. Leave a standard 3' wide door open with a 1-mile per hour breeze passing through, and it will take nearly seven tons of air conditioning to keep up on a hot day. The situation is even more costly on cold-storage warehouses, walk-in coolers and blast freezers.

Several small openings can have the same effect. Look for poorly fitting doors and windows, gaps around wall penetrations or faulty door closers.

In many warehouses, the only relief from summer heat is often air motion. Exhaust fans, open doors and circulating fans provide a breeze. But when the air introduced to the building comes in off a hot asphalt parking lot, it provides little comfort. Sometimes leaving the door closed can help improve comfort in un-air-conditioned spaces. Some warehouses stay cooler by ventilating the building at night when it's cooler outdoors, and leaving the doors closed and exhaust fans off during the heat of the day. This works best in the spring and fall when the difference between day and night temperatures is greatest. In late summer, when it's hot both day and night, this technique may not be as effective.

Maintaining air circulation with ceiling or propeller fans in the building is important and good ceiling insulation reduces heat gain through the roof. With insulation, more is better; however, it's generally not cost effective to add more than the standard 1 to 2 inches of fiberglass or 1 to 2 inches of foam later.

Program the thermostat

Constant thermostat adjustment can increase energy costs as well. A thermostat set to 55 degrees rather than 75 does not cool the room faster. If someone leaves the office and forgets to readjust the thermostat, the air conditioner is left running all night, and it's too cold by the time you get to work the next day. Then it's back to the adjustment routine. Treating your thermostat settings like a yo-yo will only pile on the energy bill costs.

Programmable thermostats can help with this. First, set a moderate temperature during occupied hours. While the amount of energy saved depends on many factors, in general, for each one-degree increase in thermostat setpoint, you can save 1-3% on your cooling energy use. Next, program your thermostat to raise the temperature 5-10 degrees when you're gone. It takes less energy to cool the space back down than to maintain the space at a colder temperature 24 hours a day. Set the thermostat to start cooling the space off an hour or so before you open, so it will be comfortable when employees arrive.

Some programmable thermostats are "smart" and figure out when they need to switch on to reach a certain temperature by a certain time. If your building uses multiple air conditioning units, each with its own programmable thermostat, set them so that the start times are staggered. This prevents all of the units from starting at once and creating a peak demand for electricity.

Keep it clean

Clean machinery runs more efficiently. Make sure you change air filters in your HVAC systems at least quarterly - more if you have a dusty or dirty work space. Be sure to inspect and clean the cooling coil. Dirty filters and coils restrict airflow through the system. If you have an air-cooled condenser outdoors for rejecting heat, make sure its fins and coils are clean. If you have a cooling tower or evaporative condenser, keep the surfaces clean, make sure water flow through the unit is even, and use good water treatment to avoid fouling.

Beauty is in the eye of the beholder

Although HVAC engineers may think their product is attractive as is, you may disagree. However, avoid the temptation to fence them in, screen them or plant shrubs around them. This can block airflow or cause recirculation of hot air through the unit.

Other measures like adding insulation, providing adequate ventilation, using light-colored or reflective roofing, reducing internal heat gain from lights and equipment, and using plants, overhangs and awnings for shade can also reduce your cooling load, saving energy and money while improving comfort.