It sometimes happens that homeowners and businesses plunge into the purchase of a new central air conditioning system expecting to see huge energy savings, and are disappointed when that doesn’t happen. While it’s true that the increased efficiency of modern cooling systems are capable of providing significant energy savings, all that can be negated by purchasing an improperly sized system for the home or office.
To be sure of buying an air conditioner that is correctly sized for a building, the best option is always to consult a residential and commercial A/C contractor, because an expert will be able to ensure you have the right fit and that you actually benefit from those potential savings.
The Air Conditioning Contractors of America (ACCA) use a formal process outlined in a document known as Manual J, which takes into account the building’s thermal gain and loss, and provides formulas used for load calculations to determine the actual amount of cooling that will be needed by each room in the building.
Over-sized Air Conditioners
Studies have been conducted on residential and commercial HVAC (Heating, Ventilating, and Air Conditioning) installations which clearly demonstrate that at least 33% of all new systems installed are over-sized for their target buildings, and thus rendered less effective than they should be. Because an over-sized system turns on and off more frequently than it should, much more energy is used than is actually required to do the job, and this completely nullifies any energy savings that might have been gained due to its more efficient modern design.
A unit that is larger than necessary will also not properly de-humidify the home or office, leaving the air feeling moist and clammy to occupants, and degrading the potential comfort level for the system.
A larger unit than is needed will also probably be noisier, and it should not be overlooked that the purchase price and installation cost will be more than a properly sized system. The bottom line is installing a larger system than needed will not provide greater comfort or increased energy savings, but will in fact do just the opposite on both counts.
Under-sized Air Conditioners
It is actually better to slightly under-size an air conditioner than to over-size it because it will require the system to run more continuously – with fewer starts and stops that consume energy – and it will contribute to longer life for the compressor. This is a fine line to walk though, and if the system is forced to run too much, it will wear out more quickly and will have to be replaced sooner than it normally should be.
Proper Sizing
Obviously, the best case scenario is to have your new air conditioner be the perfect fit for the home or office it will be cooling. When formal load calculations are done by your HVAC contractor on the building, and all relevant factors are taken into account, the ideal sized unit can be recommended, and the indoor air quality will be the best possible.
Only then can energy savings be a real possibility for the owner, and the maximum operational life can be expected from the air conditioner itself, because it will be performing in accordance with its originally designed capacity.
In every way that matters, the right size for your new air conditioner is the only size you should install!
