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What Size Air Conditioner Do I Need for My Home?

Tucson can be blistering hot in the summer, with temperatures hitting over 90 degrees Fahrenheit. In that weather, there is no question an efficient air conditioning system is indispensable. But how do you choose the most appropriate size and capacity for a cooling unit? Read on to find out what factors will determine the sizing of an efficient AC.

Room Dimensions and Temperature Requirements

Many homeowners may use the floor’s square footage to determine the size of the unit suitable for the room. Depending on the dimensions of your home, it could prove to be ideal but not the perfect size. Often you must include the vertical height, too, when calculating the area of the room.

In other words, the height and area of the wall will be crucial in determining the capacity of your air conditioner. The greater the volume, the more powerful the cooling system has to be. You don’t want a unit that will struggle to keep your home comfortable.

When it comes to AC systems, the unit for measuring their capacity is BTU (British Thermal Units). Generally, it is the amount of energy required to raise one pound of water by a degree Fahrenheit at sea level.

On average, a room of 250-square feet will require 6,000 BTUs. However, there are many variables that technicians will include in their calculations. A professional has to factor in your home’s climate zone.

Arizona is in climate zone four, which could mean you need a higher capacity to cool. A home in the zone will typically require 40 to 50 BTUs per square foot. A 250-square-foot room, therefore, will need a capacity of up to 2,500 BTUs.

Why Precise Sizing Is Essential for Efficiency

To prevent energy losses and maintain the system’s longevity, the size of your AC has to be precise. A unit that is oversized or undersized will have implications for your comfort. There could be a temptation to go for a smaller air conditioner for economic reasons.

An undersized system will run continuously to keep up with the heating demands of the building’s interior. It will cycle continuously, contributing to faster wear and tear of your equipment’s components. Continuous cooling removes air from the room too quickly, contributing to drier, less humid air.

An air conditioner that is bigger than the room will also have undesirable results. It may keep switching on and off to avoid overcooling your home. The unit will also struggle to remove humidity, making the interior of the building uncomfortable. The room may get too hot or too cold.

If the sizing is incorrect, you also have to factor in additional expenses associated with a substandard installation. For both oversized and undersized units, you will use more energy and resources to regulate temperatures. Your air conditioner may break down frequently due to faulty and worn-out components.

Consider Your Location and Grade of Insulation

Other variables could influence your choice of an air conditioning system. Your area’s climate is an essential factor when determining the capacity of your AC. The weather will decide the insulation material to use in the attic, crawlspaces, and walls.

Tucson is in zone four, which means you’ll need insulation with an R-value of between 30 and 38. According to, you can save up to 20% of energy by ensuring you have the correct insulation grade.

Additionally, cracks and holes in the attic’s insulation can allow cold air to escape outdoors in the summer. Your air conditioner will have to overwork to keep the interior comfortable and cozy. Some homes may install a radiant barrier or attic fans to manage heat and air circulation in that space.

Before choosing the right-size air conditioner for your home, it’s essential to address those issues first. It will be challenging to determine the capacity you need when there is air escaping from the room.

An energy audit is necessary to establish where your home is losing energy. You can consult Rite Way Heating, Cooling & Plumbing in Tucson when you want to install a new system.

Sizing Your AC and Energy-Efficiency Ratings

You must also understand energy-efficiency ratings when trying to find the correct capacity of an air conditioner. The most recent models of cooling systems are much more efficient than their older counterparts from a decade ago.

SEER (Seasonal Efficiency Energy Ratings) is one of the well-known standards for measuring the efficiency of an AC. Since 2015, the Department of Energy has come up with new guidelines that factor in the region’s climate and weather.

If you have an older system with a lower rating, upgrading could yield significant energy savings. You can save between 30% and 40% of your power usage if you choose a system with a SEER 14, up from a rating of 10. Some systems can attain even higher levels of efficiency, up to SEER 21 and above.

An Energy Star rating shows the AC is much more efficient than others of the same model and size. It also shows the model complies with EPA guidelines on environmental safety. However, those units may be too expensive for some homeowners. You can still acquire an efficient model that is within your budget and can address your needs.

It’s wise to consider the benefits against the cost of acquiring a system. If you are unsure what unit to choose, you can consult our team at Rite Way Heating, Cooling & plumbing. We are a Lennox Premier Dealer, but we have experience working with a wide range of AC models and brands.

Orientation and Other Factors Influencing Efficiency

A home that receives a lot of sunlight in summer will need more BTUs per square footage. So our AC professionals have to consider exposure to sunlight, shading of trees, area of the walls, and the house’s orientation. Similarly, some rooms may require a higher capacity system due to ambient heat from heating equipment like cookers.

The rule of thumb is to allocate a 10% higher cooling potential for rooms that receive a lot of sunlight. For those that receive little to no daylight, the capacity is 10% lower than average. The number of occupants that frequent the room can increase the amount of heat in the interior.

Experts recommend that you add 600 BTUs for each person in a home with more than two occupants. If you use the unit in a kitchen, the capacity requirements will be higher than for other rooms in the house.

Ultimately, the best approach is to organize for an energy audit. That way, you will unearth issues such as inadequate insulation before you decide to install an AC. An energy audit will also decrease your risk of installing a system that doesn’t match your home’s requirements.

If you’re considering replacing your air conditioner, you can count on our top-rated team in Tucson. We are a BBB-accredited business with decades of experience in the maintenance, installation, and repairing of heating or cooling systems. Our company has an A+ rating and can troubleshoot Trane, Lennox, and other models of AC/Heat equipment. We also offer indoor air quality, duct cleaning, and energy audits. For exceptional services in Tucson, contact Rite Way Heating, Cooling & Plumbing today.