What Size AC Unit Do You Need? A Guide to Proper Size
Summary:
Calculating the square footage of your home is essential to proper AC unit sizing. While most homeowners do not bother with this, accurate sizing ensures optimal cooling performance, energy efficiency, reduced utility bills, and long-lasting equipment.
Table of Contents
Introduction
Selecting the correct AC unit size for your home is not just a matter of comfort. This decision is vital for ensuring energy efficiency and the longevity of your HVAC system.
An air conditioner that is too small won’t cool your home adequately, forcing it to work harder, straining your system, and potentially leading to a system breakdown. Meanwhile, one that is too large will cycle on and off too frequently, leading to increased wear and tear and more repairs.
So, how do you choose the right AC size? In this guide, Klondike Air experts will help you figure out the perfect size AC for your home, bringing insights and knowledge from over 30 years of professional AC installation in Orange County.
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Understanding BTUs and Cooling Capacity
The BTU or British Thermal Unit is a standard used to measure the heating and cooling power of air conditioning and heating units. Specifically, one BTU is the amount of energy required to raise or cool the temperature of one pound of water by one degree Fahrenheit.
BTU measurement is essential to understanding the cooling capacity of your HVAC unit; higher ratings indicate that your system can achieve the desired temperature efficiently.
Understanding this measurement, how to calculate it, and the factors that can affect your calculations can help you choose the perfect AC unit size for your home, guaranteeing energy efficiency and system longevity.
Factors That Affect AC Sizing
There is no one-size-fits-all solution in AC installation. If you are in the market for a new HVAC unit, here are some factors that will help you choose the correct size:
1. Room Size and Layout
When choosing an air conditioner for your home, consider the size and layout to ensure proper selection. For instance, large rooms require units with higher cooling capacities, while smaller ones need less powerful ACs.
You can calculate the square footage of your home by multiplying the width and length of each room.
2. Climate and Insulation Levels
Your region’s climatic condition and insulation level in your home also plays a significant role in AC unit sizing. Homes in hotter climates typically need higher capacity air conditioning units, while those in colder climates can manage with smaller AC units.
Additionally, homes with high-quality insulation can easily prevent conditioned air from escaping to the outdoors, and thus will require AC units with fewer BTUs. However, if there are gaps or openings in your windows, attics, doors, or ceilings, you’ll need an AC with a bigger cooling capacity to keep your home comfortable in the summer.
3. Wall Height
The height of the walls in your home will affect the size of your air conditioner. While size and layout only consider the length and width of your home, it doesn’t account for height. So rooms with tall walls will require a large air conditioner, while those with short walls can do with smaller AC sizes.
4. Windows
The number of windows in your home helps determine the air conditioner size you need. Windows are a source of heat gain. During the day, sunlight will beam through your windows, warming your space. So, if your home has many windows, you will need a large air conditioner to cool your space effectively.
5. Number of People in Your Home
The human body generates about 120W/h of heat. Typical BTU works on the assumption that each room in your house has two people. So, if you have more than two people occupying a space in your home, you must add 600 BTUs per person per hour. Also, if you have an indoor gym, the workout will increase the heat in your room, so you will need a larger air conditioner to cool the space and make occupants more comfortable.
Using an AC Size Calculator
Need to calculate how many BTUs your air conditioners need to perform efficiently and effectively? Follow this step-by-step guide:
1. Step-By-Step Guide to Estimating Your AC Needs
During the installation of air conditioning system units, you must appropriately estimate your cooling needs, as it informs the AC unit size you need. Here are some steps to evaluating your cooling needs:
- Measure your space: Measure the length and width of your home to get its square footage. For instance, a room measuring 12 feet by 18 feet equals 216 square feet, which is the space you need to cool.
- Choose the right BTU rating: The U.S Department of Energy recommends approximately 20 BTUs per square foot of living space. Therefore, a 216 square foot room would require 4,320 to 5,000 BTUs.
- Consider other factors: AC unit size calculators often include adjustments for ceiling height, sunlight, occupancy, and the room’s purpose. Rooms with ceilings higher than 8 feet may require additional BTUs. Same for homes with significant sunlight exposure, requiring a 10% increase in AC unit sizing. Our experts recommend adding an extra 4,000 BTUs to the capacity for kitchens and other rooms that produce heat. And add 600 BTUs for each additional person beyond two occupants.
2. Avoiding Undersized and Oversized Units
To avoid undersized or oversized air conditioning units, you must consider factors that can affect the accuracy of your BTU calculations, such as room size, insulation, sun exposure, and climate. Choosing the wrong AC unit size can affect energy efficiency, system performance, and lifespan.
An oversized air conditioner may cool your home faster than other systems. Still, they fail to maintain consistent temperature, while an undersized system will struggle to meet your cooling demands, leading to overwork and higher energy bills.
Imprecise calculations will also affect the performance of your system, leading to premature wear and component failure, driving up repair and replacement costs.
AC Installation Considerations
Here are some factors to consider before the installation of air conditioning system units:
- Size of the room: Before installing an air conditioner, you should ensure that the size matches the air conditioner’s cooling capacity. An undersized system will struggle to cool your space, while an oversized one will cycle on and off too frequently.
- Ventilation: The role of your air conditioner is to distribute conditioned air. To do this effectively and ensure even distribution to all corners, your AC unit must have access to adequate airflow. Without airflow, air becomes stagnant, forcing your system to cool the same air repeatedly.
- Location: Choosing the perfect location is essential for the efficiency and longevity of your AC system. If your system is placed under direct sunlight, it becomes susceptible to external heat, making it hard to cool its internal components or the air it circulates. This leaves your air conditioner to work overtime to cool your space, consuming more energy, accumulating wear and tear, and eventually breaking down.
- Noise Levels: Noise is a significant factor when installing air conditioners. Larger units produce more noise when running. And during the summer, when your AC runs for long periods, the constant humming can affect stress levels, causing sleep disturbances and cognitive disruptions.
- Professional Installation: Your air conditioner is an essential home safety equipment. A professional should install the equipment to prevent damage and long-term efficiency issues.
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End Note
Adopting a one-size-fits-all approach to air conditioner installation is the worst decision you can make as a homeowner. Apart from the obvious impact on cooling performance, installing the wrong AC unit size can impact system longevity, utility bills, and the lifespan of your system.
As the premier AC installation contractor in Orange County, we have seen homeowners make this mistake repeatedly and bear the substantial financial cost of their decision. The only remedy for installing the wrong AC size is to uninstall and get another system. So, it is better to get it right on the first try. Contact us at Klondike Air for more information and assistance on proper AC sizing.
FAQs
How do I determine what size AC unit I need?
The U.S. Department of Energy recommends multiplying your square footage by 20 BTUs to get an accurate AC size for your home.
Is it better to oversize or undersize AC units?
Neither oversizing nor under sizing is ideal. Oversizing can lead to frequent short cycling and energy wastage, while under sizing means your system will struggle to meet cooling needs and increases AC wear.
What is the rule of thumb for sizing AC units?
Regarding air conditioning, the rule of thumb is that one ton of AC can cool approximately 450 to 600 square feet of living space.
How big of a room will a 12,000 BTU air conditioner cool?
A 12,000 BTU air conditioner can cool a 500 to 700 square foot home.
What happens if an AC unit is too big?
An oversized AC unit will quickly cool your home, but not all spots will be efficiently covered. It can also raise energy bills and increase component wear.
What happens if you put a small AC in a big room?
An AC that is too small will work harder to cool your room. This can cause your air conditioner not to cycle properly or not shut off at all, causing excess wear and tear and increased repairs.
Does the size of an AC unit matter?
A properly-sized AC unit will work efficiently to cool your home, not running too little or too much. It will also optimize energy consumption and comfort.
How much space is needed around an AC unit?
An AC unit needs 1 foot minimum on all sides, including behind the unit.
What happens if the BTU is too high?
Choosing an overly high BTU unit will lead to high energy consumption and inefficient AC performance.
What do you consider before buying an air conditioner unit?
Consider room size, cooling capacity, energy efficiency, type of AC, installation requirements, noise levels, and maintenance needs.
