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Home Care Library

Central Air Conditioning


The neighbor in the video mentions planting shrubs around the A/C unit to make it more energy efficient. Please explain.


Dear Peter:

. . . sure, glad to explain.

The short answer is that placing shrubs around it, the shrubs help to keep your outside air handling unit at a lower temperature (by blocking the sun and providing shade), so that it makes this air handler's job easier. Since your outside air handler's job is to draw the heat away from the inside of your house, if this air handler is baking in the sun, it gets hot and makes it harder for the unit to get the heat away.

For a longer answer on how a home air conditioning system works, this webpage provides a fairly good explanation:

One thing to consider when planting shrubs around an outside air conditioner unit, is that you do not want to place the shrubs so tightly around the unit that it doesn't leave room for the unit to "breathe". Air needs to circulate freely around the unit, so that it can easily dissipate the heat that it has brought from inside your house.

One last thing to consider is whether your AC unit is already in the shade. If your house, trees, etc. are already shading the unit, then you don't need to add the shrubs.

Hope this is helpful.

If you have additional questions, just let us know.

Also, we hope that you are finding our monthly videos to be both informative and entertaining.



OK, hopefully you can settle a debate. My sister says that running the Central AC on manual so that the air is constantly circulating is more energy efficient than having the Central AC on Auto.

I know that having it off completely when not home, using ceiling fans, closing off vents/rooms that are not used, closing curtains & blinds, etc. helps to save.

But what about the AC fan blowing all the time?


Dear Tom in DC:

The answer is that it depends somewhat on your particular system and climate where you live, but in general, it is better from an energy efficiency standpoint to have your central air conditioning system running in auto mode versus leaving the fan in the continuously on position.

The reason is that in most situations, that running your air conditioner's fan in the continuously on position causes the moisture that is removed from the air when it is cooled, to be redistributed back into your home's air. And because this leaves the humidity in your home higher than compared to running it in the auto position, it makes your home feel less comfortable, resulting in typically the need to reduce the set temperature on the thermostat, which then has your air condenser unit running more often and therefore consuming more energy.

Now if you are in a very dry climate and you have a fan with variable speed drive, then this will not be as much of an issue. But again, in general, it is better from an energy efficiency standpoint to leave your central air conditioning system in the auto position (and as you pointed out, use a programmable thermostat and the other energy-saving methods that you suggested).

Hope this is helpful.

Central Air Conditioning