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What Size Air Conditioning Unit Do I Need?

air conditioning essex

Are you thinking about installing an air conditioning unit but aren’t sure what size you need?

Selecting the appropriate size air conditioner is essential for creating a comfortable living space while keeping your energy costs low. An air conditioning unit that’s too small for your room will have to work harder and longer to cool the area, resulting in higher electricity bills. Additionally, a unit that’s too big will power on and off too frequently, failing to dehumidify the air properly and causing temperature fluctuations.

At GLP, we understand that finding the perfect air conditioning solution can be confusing, especially if you’re installing one for the first time, so we’re here to guide you through the process, helping you determine the ideal size unit for your home’s needs.

How To Choose The Right-Sized Air Conditioning Unit 

To determine the perfect size for your air conditioner, start by accurately measuring the dimensions of the room it will be cooling. Use a tape measure to note the space’s length, width, and height. Then, multiply these three figures together to calculate the total cubic feet.

For example, if your room is 15 feet long, 12 feet wide, and 8 feet tall, the calculation would be:

15 x 12 x 8 = 1,440 cubic feet.

Or, if you’re feeling lazy you can use our easy-to-use interactive quote calculator to help you estimate the potential costs of installing a unit in your home. 

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Find the BTU (British Thermal Unit)

When we talk about measuring the size of your unit, we’re not referring to its dimensions but rather its cooling capacity, measured in British Thermal Units (BTUs) or kilowatts (kW).

BTU is the amount of heat an air conditioner can remove from a space in one hour. Once you have the room’s cubic footage, you can estimate the required cooling capacity in BTUs. Generally, you need about 20 BTUs per square foot of living space.

Other Factors to Consider

While the room’s size is the main thing to consider when choosing your AC unit, several other factors can influence the cooling needs of your home. 

The Direction Your Home Faces

If the room has large windows that receive direct sunlight for much of the day, you may need to increase the BTU capacity by 10% to account for the additional heat gain. This will ensure your AC unit can effectively cool the space despite the extra heat from the sun.


Well-insulated homes can maintain desired temperatures more efficiently, reducing the workload on your air conditioner. If your home lacks proper insulation, you may need to compensate with a slightly larger AC unit to account for the heat coming from your walls, floors and ceilings.


High humidity makes the air feel warmer, requiring more cooling power to maintain comfort. In particularly humid climates, increasing the BTU capacity by about 10% is a good idea to ensure your AC unit can effectively dehumidify the air.

Your Home’s Layout

Open floor plans help improve the ventilation in your home, by allowing cool air to be distributed more effectively. However, if your home has many separate, closed-off rooms, you may need multiple units or a larger central system to make sure there is even cooling throughout the entire house.

Choosing The Type Of Air Conditioning Unit You Need

Now that you have a better idea of how to calculate the cooling capacity required for your room, it’s important to consider the various types of air conditioning units available and what one might be the best fit for your specific room size and layout.

Wall Mounted Unit 

Wall-mounted air conditioners are a popular choice for single rooms or smaller spaces and are relatively easy to install, providing efficient cooling without wasting floor space. These units are ideal for rooms such as bedrooms and home offices.

However, wall-mounted units may be less effective for larger or open-plan spaces, as their cooling is more targeted to a specific spot. Additionally, installing a wall-mounted unit requires a suitable external wall for the outdoor component of the unit.

Floor Standing Unit 

Floor-standing air conditioners are a flexible alternative to wall-mounted units. These units can be positioned anywhere in the room as long as there’s a power socket nearby and a window to vent the exhaust hose. 

Floor-standing units are convenient for those who want to avoid a permanent wall installation. However, they take up floor space and may not be as visually appealing as other options.

Ducted Unit

A ducted air conditioning system could be the best solution if you have a larger home or multiple rooms needing cooling. This type of system features a central unit that cools the air and then distributes it through a series of ducts hidden in your ceilings or floors.

The main advantage of a ducted system is its ability to cool the entire home evenly and efficiently. They allow you to set different temperatures for individual rooms or zones, giving you greater control over your comfort and energy use. However, they are more complex to install and usually cost more than single-room units.

Portable Unit

Portable air conditioners are perfect for those who need a temporary cooling fix or want the freedom to move their unit between rooms. These compact units can be easily wheeled into place and typically require minimal installation, such as venting the exhaust hose through a window.

While portable air conditioners offer the benefit of mobility, permanently installed units may be less powerful and efficient. They can also be louder and take up more valuable floor space than wall-mounted or ducted systems.

Enhance Your Home’s Comfort With Air Conditioning 

Our team of skilled technicians will work closely with you to determine the perfect cooling solution for your home, making sure you have the right-sized unit for the best performance. We’re committed to providing professional services and expertise from initial inspections to installation and repairs.

Contact us today to learn more about how we can meet your air conditioning needs.

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