When considering an HVAC unit for your home, don’t just go with the largest system; if you choose a system that’s too large, the AC unit will not efficiently cool your home and could cause problems for your indoor air quality. The EnergyStar website includes a calculator as well as a table with instructions for the size of a home and the recommended cooling capacity of an air conditioning unit. However, the easiest way to determine the best new air conditioner for your home is to have a professional AC technician assess your space and determine the appropriate equipment to meet your comfort needs.