Portable air conditioners—though less efficient than the newest central air conditioners—can still help trim energy costs when used properly.

Using natural fresh air ventilation is always the most energy efficient, but outdoor allergens can certainly be a problem for many people. In many cases though, indoor air is more polluted than outdoor air. Check with your physician to make sure the allergens to which you or family members are sensitive are truly coming from outdoors and are not indoor-generated.

If you were going to air-condition just for the clean air circulation, but not necessarily for the cooling, there are several other options to also consider. Heat-recovery fresh-air ventilation is a good option for year-round fresh air. Most systems include effective air cleaners to remove allergens from the fresh air before it enters the system.

Another option is ducting some fresh air into the return air system. Run the system on “fan-only” with no cooling and allow a high-quality central air cleaner to remove the allergens. This is most efficient if your central air handler has an efficient variable-speed blower which can be run at a relatively low speed.

Using a portable air conditioner—which are often heat pumps—would also be an effective solution for your family.

I use a portable heat pump in my own home/office for year-round savings. In addition to cooling the room during summer, it also functions as an efficient portable heater during winter. It produces 14,000 Btu per hour (Btuh) of cooling and 11,000 Btuh of heating. This is much more heat output than a standard electric space heater using the same amount of electricity during winter.

The efficiency of a portable air conditioner is similar to a window air conditioner. Although this is less efficient than the newest central air conditioners, using one can still save money. By keeping just one or two rooms comfortably cool with clean air, you can set your central thermostat higher and save electricity overall. Use it in the dining room for dinner, roll it into the living room for television, and then to the bedroom for sleeping.

They are typically mounted on castors so they can be easily rolled one from room to room. Most operate on standard 120-volt electricity, so they can be plugged into any wall outlet near a window.

A portable air conditioner/heat pump operates similarly to a typical window unit. The internal rotary compressor, evaporator and condenser function in the same way. The primary difference is it is on castors and rests on the floor. Most are light enough to easily roll from room to room. The higher-output models, such as the heat pump model I use, is fairly heavy. It would be difficult for most people to move it up and down stairs, but it still rolls easily.

Round air ducts, similar to dryer ducts, connect the unit to a window adapter. You open a window, place the adapter in the opening and close the window against it. This exhausts the heat outdoors when cooling.

There are two basic designs of portable units. One uses a single duct to the window adapter. This is the simplest system and works well, but it does draw some cooled or heated room air to the outdoors. I use a one-duct model, with a remote control, in my second-floor bedroom to precool it at night. Then I set its thermostat higher so it does not come on much overnight.

The other design uses two ducts, which is more efficient. All of the air flowing through the condenser (which carries the heat away) is drawn from outdoors and exhausted back outdoors. With two ducts, no already-conditioned indoor air is being exhausted outdoors. This is more energy efficient, especially when operating a heat pump model in the heating mode during winter. Some two-duct heat pump models can also be set up with only one duct for quicker installation.

Another feature to consider is how the condensed water is handled in the cooling mode. Some evaporative models mix it with the air exhausted outdoors so there is nothing to empty. Other models, which also work well as dehumidifiers, capture the water in a small tank which you must empty—I use the distilled water from the tank to water my plants.

The following companies offer portable air conditioner/heat pumps:
Fedders, 609-662-5300;
Soleus Air, 513-985-1211;
Sunpentown, 800-330-0388;
Toyotomi, 203-775-1909; and
Windchaser, 800-405-2943.

Have a question for Jim? Send inquiries to: James Dulley, Michigan Country Lines, 6906 Royalgreen Dr., Cincinnati, OH 45244 or visit dulley.com.