What Size AC Do I Need for My Tucson Home?

Hot Tucson summers often necessitate the use of air conditioning. However, for optimal results, you need the right-size AC for the job. You might have seen ACs labeled with BTUs on them. What is a BTU? Simple: It's a British thermal unit, a way of measuring how much heat is necessary to raise the temperature of 1 pound of water by 1 degree Fahrenheit when it's at 39 degrees F. The BTU on an AC determines how much heat it removes from your environment in an hour.

The size of your home is an important consideration, but it isn't the only factor that affects how strong your AC needs to be. Others include:

While this isn't a comprehensive list, it does consider the most important elements in determining the right-sized unit for efficient use.

When your AC is too big for your home, it short cycles, turning off and on far more frequently than it should. This can result in uneven cooling, higher energy bills, and excessive wear and tear, shortening your AC's life span.

Conversely, an AC that's too small can't cool quickly enough. This can lead to it running constantly, creating the same issues as an AC that's too big.

That said, the more accurate way to determine the correct size for an air conditioner is to perform a load calculation. This calculation considers all factors that determine how much heat needs to be moved in and out of your home, including your climate, ceiling height, the number of people in your home, and much more.

While the size of a home can provide a general guideline for how much AC power you need, much more also impacts it. For example, the height of your ceilings matters, as do the number of doors and windows throughout your house. The location and quality of your ductwork, which is part of your home's layout, can also affect how efficiently your home is cooled. Other layout-related factors include whether your home faces south and receives more direct sunlight or whether you have trees shading your home. Darker exterior paint also leads to more heat absorption than lighter colors.

A reliable HVAC technician evaluates your home to identify exactly how big of an AC you need.

Energy efficiency significantly influences an air conditioner's effectiveness in cooling a home, affecting the size of the AC unit you might need. This efficiency is standardized through the Seasonal Energy Efficiency Ratio (SEER), which quantifies how efficiently an air conditioner utilizes the energy it consumes. Generally, the SEER rating is as crucial, if not more so, than the British Thermal Units (BTU) rating, which measures the unit’s cooling capacity. A higher SEER-rated air conditioner typically performs better than a lower-rated one of the same BTU, leading to more efficient energy use and potentially lower electricity bills.

Add-on features can also improve AC efficiency and reduce how much cooling power you need. For example, a dehumidifier reduces overall humidity in the home. Dryer air is easier to cool, reducing the amount of energy necessary to drop the temperature. You can add a dehumidifier to an AC unit, which may factor into the size recommended by your technician.

Certain potential modifications may also influence the size of AC you need. For example, if you have a sunroom that you'd like to hook up to your AC but no ducts go there, you may be able to add a ductless mini-split. However, this space will need to be considered when determining the overall size of your AC.

Believe it or not, the contractor you hire can also have a big impact on the size AC recommended to you. Some may simply use an AC size calculator based on square footage to determine BTU.

Trustworthy HVAC technicians perform calculations to help optimize your AC unit size to your specific use case scenario. You may need a smaller unit than your square footage implies, and a trained, reliable technician will know this.