Discover Why Air Conditioner Sizing Matters

Planning to install an air conditioning system? You have to understand that size matters. The general criteria to determine the size of an AC is usually the room size. However, there are other various factors to consider. These include incoming air volume, wall insulation, wall material, humidity level, flooring material, and temperature difference. 

Here are the most significant factors for AC sizing

Room size

The size of your space determines the size of your AC. This requires multiplying the width and length of the room. The results allow determining the area for cooling or heating. For a space, not precisely square or rectangle, dividing it into different sections allows calculating the exact size. The next step is to determine the air conditioner BTUs suitable for the space. Determining this is by multiplying the total area of the room by 25. Each square foot requires 20 BTUs. A room that is usually empty requires few BTUs compared to one always occupied. 

Room height

Apart from the area, determining the right size for your AC also depends on the height of the space. Height plays a significant role in determining the adequate cooling capacity. The presence of a very high ceiling in a room avails more air that needs cooling. So, wall-mounted mini-split air conditioners are more effective at cooling such an area compared to window-mounted AC units. Positioning mini-split ACs higher on the wall allows effective cooling since warm air rises. 

Wall insulation

When considering air conditioner installation in Houston Tx , you have to consider wall insulation. Insulating the walls requires embedding non-conductive material in the walls. This keeps the space cool in summer and warm during winter. Wall insulation is highly effective at thermal insulation. It doesn’t conduct efficient heat leading to the prevention of cooling loss in summer. 

If your place has good wall insulation, you’re likely to save on air conditioning. This is because your room doesn’t lose heat quickly. For spaces without insulation, it means your room becomes warm quickly after turning off the AC. you’ll have to keep it running for extended periods in a high-power setting. 

Nature of windows

The type or number of windows determines the AC sizing. Energy-efficient windows like double-pane or low-e reduce the required BTUs. Windows determine the amount of incoming light and natural light brightens a room. On the flipside, windows encourage excess heat in hot weather. Having too many windows can potentially increase your BTU requirement by 10 percent. Applying energy-saving treatments like tinting can help.

Humidity levels

The presence of more water vapor in the air means more use of the AC unit. Cooling the room requires using the AC to work as a dehumidifier. Removal of excess moisture in the air makes a significant difference in the room temperature. The space becomes more comfortable. If you live in an area with high humidity throughout the year, you have to invest in an AC unit with extra capacity. 


The location of your home determines AC sizing . If sunlight falls directly on your home, you need a bigger AC unit compared to a home with trees creating shade from direct sunlight. Direct access from the sun increases the cooling capacity of the home by about 20 percent. Additionally, the purpose of your space also determines the capacity of the AC. Cooling the kitchen increases BTU requirement by 4,000 compared to other areas in the home. 

Number of occupants 

According to Energy Star, you have to increase the cooling capacity of your space by 600 BTU for each person. This applies when having multiple people in the space for the most part of the day. The human body generates heat making the AC work harder in an occupied room. Air conditioner efficiency in the room will depend on the number of occupants. 

Signs to tell poor AC sizing 

Short cycling

An AC that frequently activates and deactivates shows it’s too large for your space. Being powerful, the unit will operate for a short period while running on excess electricity. Alternatively, a properly sized unit operates for longer cycles at low capacity while using less electricity. 

Continuous cycles

A small AC has to run continuously throughout the day to ensure a low temperature and humidity. This leads to a hefty electricity bill at the end of the month. Additionally, running continuously significantly reduces the life cycle of the unit . A poorly sized AC encourages very warm or humid air in the space. 

Presence of warm and cold spots

A bigger AC achieves the programmed temperature too soon. This results in the unit deactivating before cold air reaches every room in your home. The presence of warm areas in the home requires calling a professional AC installer to evaluate your appropriate cooling and heating requirements. This allows selecting the right size for your requirements. 

An air conditioner ensures a comfortable environment all the time. When replacing or installing a new unit, sizing matters. Working with a professional installer avails expert advice regarding selecting the right-sized unit for your requirements.