When it comes to home air conditioning, there are two options: window units and central air conditioning. Window units are designed to work for a small number of rooms, and can be turned on or off for comfort. Central air conditioning is a system that runs throughout your home, with vents to evenly distribute cool air.
Some homes have both types of air conditioning. If you are trying to decide which of the systems to use, consider the energy consumption of each. Window units typically use less energy, but don't cool as evenly as central air.
Should you close off vents in unused rooms if you opt to use a window unit? It makes no difference whether you close off central air conditioning vents or not. You might consider shutting the vents to be positive that none of your air conditioning escapes through them. However, if you leave them open you shouldn't receive any significant air loss.
If you are using a window unit, you may wonder does closing off unused rooms save energy? Unlike a central air conditioning system, you can save energy by shutting doors to rooms you're not using. Doors act as barriers to air flow, so if you want air to remain in one room, closing off additional rooms could help.