Should I Close My Air Conditioning Vents in Unused Rooms to Save Energy?

January 22, 2014

If you are concerned about the energy efficiency of your home comfort system, you may have heard that you should close off air conditioning vents in unused rooms.

For example, if you have a guest bedroom that is almost always unoccupied, some people will tell you that you should close the vents (also called registers) and shut the door to the room in order to reduce your energy use. But is this true?

The reasoning behind closing the vents

It seems logical that closing off an unused room would use less energy. After all, that means there’s less space for your air conditioning system to cool, right? Smaller homes cost less to cool, and this is just one way to make your home seem smaller.

Unfortunately, this isn’t quite the case.

What really happens when you close off unused rooms

Modern air conditioning systems are balanced when they are installed. In other words, they are adjusted so that the right amount of air comes out of each vent and that is perfectly balanced with the amount of air that is sucked up into your air conditioner through your return vents.

This ensures more even temperatures and helps eliminate hot and cold spots by, for example, sending more air to bigger rooms and less air to smaller rooms.

So when you close off vents in unused rooms, you’re actually messing with this balance and creating pressure, which can actually make your air conditioning system work HARDER. This pressure can also cause or aggravate leaks you already have in your ductwork, making your system even less efficient.

So what SHOULD you do?

Leave all your air conditioning vents open. If you want to save energy by sealing off unused rooms, consult an HVAC professional as you may have other options, such as a zoned system.

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