Air Conditioning or Ceiling Fans

If you live in an area with hot, humid summers, what is the most effective way to keep cool, air conditioning, ceiling fans, or some combination of both?  Are there energy efficiencies to be gained from the way you use your cooling equipment?  First, let’s look at air conditioning.

Surprisingly enough, less than half of all Australian homes have air conditioning.   While all air conditioners are energy gluttons, some are less so than others.  The least efficient are window and wall mount units.  Split system air conditioners are usually more energy efficient in larger applications and newer systems add a variable speed drive “inverter” to the blower motor, making the unit more energy efficient to operate, but more expensive to buy.

Programmable thermostats can help with split systems by controlling the start time and duration as well as the desired temperature.  For example, you can set the thermostat to shut the unit down when you leave for work and turn it back on an hour before you return. You can set the unit at a higher temperature at night when it is cooler and a lower temperature during the peak daytime heat periods.  For people with widely varying schedules, more expensive thermostats offer a wider range of programming options.   What about ceiling fans?

In effect, ceiling fans cool people, not rooms.  The gentle air flow over the body makes us feel cooler even though the temperature in the room may be high.  Many homeowners use them in conjunction with their air conditioners to circulate the cooler air delivered from their window or wall units.  The way to maximize energy efficiency is to allow the air conditioner to drop the temperature of the room a degree or two and then shut it down and let the ceiling fans circulate the air.  Depending on how well insulated your home is, the cool air may remain for an hour or more when the air conditioner can be turned on again.  Timers can be added to window and wall units to make this process easier.

Ceiling fans are by far the more energy efficient of the two and many homeowners in more moderate climates get along fine with ceiling fans only.   They come in a wide variety of sizes and decorative styles to enhance any decorating scheme.  In days gone by choices were limited to plain blades in white or faux wood colors.  They have become so popular that now you can find blades resembling palm fronds, high tech chrome housings, and a wide array of dramatic colors.  To get the most out of a ceiling fan, look for one with the maximum number of blades and the longest blades possible.  A five blade 137cm (54”) fan cools better than a four blade 1200mm (48”) fan.

Even with programmable thermostats and timers, many homeowners fail to take advantage of a simple and inexpensive cooling method:  a night time shower.  Many homes have the bedrooms on the second floor and it is very rare for split system air conditioners to keep the second floor of a home as cool as the first floor.  This prompts some homeowners to place small window units in their bedrooms for night time comfort.  When you head upstairs your body will notice the difference in temperature and you may feel uncomfortably warm, prompting one to crank up the air conditioner and then wake up in the middle of the night, now uncomfortably cold.  As an alternative, take a short, cooling shower before retiring which in effect “neutralizes” the temperature differential between the first and second floor.  If you must use a window unit, turn it on an hour before retiring and shut if off when you go to bed and let your ceiling fan do the rest.