In general, several factors determine how much heating and cooling your home requires, including the overall square footage of your home. But your heating and cooling load is also based on your home’s unique characteristics.

In fact, Consumer Reports warns to “be leery of a contractor who bases estimates merely on house size or vague rules of thumb.” And, according to the U.S. Department of Energy, “well over half of all HVAC contractors do not size heating and cooling systems correctly.”

That’s why having a load calculation performed prior to installing a new system is vital to ensuring an efficient cooling and heating system and lower energy bills.

It’s true that the tonnage of an A/C or heating system – and therefore the cost – is largely determined by a home’s square footage. As a result, a larger home will always require a larger system than a smaller home. But variations in home design should also be factored in to a load calculation to ensure efficiency.

Because all homes are unique, even homes that are identical in square footage won’t necessarily require the same system capacity. A load calculation also should evaluate:

• Insulation. A well-insulated home keeps conditioned air inside, so there is less energy loss – and that means the heating and cooling systems are required to produce less conditioned air. Appropriate insulation levels reduce the heating and cooling load and therefore often make it possible to purchase a smaller system.
• Air leaks. When a home leaks air, it also loses energy. A home with lots of air leaks, therefore, will require additional conditioned air – and possibly a larger system.
• Design factors. Elements within a home, such as a multi-level space or one or more rooms with high ceilings, often require additional heating and cooling in order for the home to remain comfortable. High ceilings, for example, trap more heat and therefore require more cooling to compensate.

When an expert performs a load calculation, the above factors should be taken into account, along with indicators such as the local climate, number of windows and energy produced in the home by appliances.

Are you considering installing a new system? Get a load calculation from the heating and cooling experts at Jon Wayne Heating & Air Conditioning. We have been proudly serving Greater San Antonio for more than 30 years.

Our goal is to help educate our customers about energy and home comfort issues (specific to HVAC systems).  For more information about load calculation and other HVAC topics, download our free Home Comfort Resource guide.

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