There are inherent benefits to cooling the whole house including better air circulation, filtration and the elimination of cold or hot spots. However, there are times when cooling the upstairs bedrooms don’t make sense if no one is sleeping in them. There are two real options to successfully zoning your cooling space. The first is to invest in a second air conditioner and have one cool the most active space and the second be on ‘standby’ for the lesser used space. This requires the rerouting of your duct work but can provide additional controls for times when both spaces are used. The second option is to use a high efficiency system which can provide cooling modulation to adapt its power output based on which zones need to be cooled. Because the high efficiency systems are able to throttle up or down they are able to maintain humidity control and air flow and thus, overall air quality and comfort won’t be negatively affected. If you try to shut off rooms with a single, lower efficiency, fixed capacity system it can lead to moisture/humidity problems as well as spikes in temperature to make you uncomfortable. You could also severely damage the system if you shut off too many vents. Zoning is an excellent way to save on energy costs, but your contractor should help you select the right equipment to support that approach.
What is SEER and Why is it Important?