Those SEER 29 units are available but in my short time once selling AC units, most went for the lowest cost unit available. Those cheaper units are not as effic

Those SEER 29 units are available but in my short time once selling AC units, most went for the lowest cost unit available. Those cheaper units are not as efficient. With split units the maximum efficiency attained is in the hands of the customer. Great for customer freedom, but not so great for the environment if the lowest of the low in AC units are available. Semi-related question: How is fresh air turnover handled in apartments with split AC units?