Consider before you cool: Must-know info before purchasing an Air Conditioner

November 11, 2021

7 minute read
Picking a new AC for your home or workplace can be as simple as choosing the most expensive model with the highest ratings, best reviews, or most confident recommendation from your dealer.
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Choosing the best aircon brand in the Philippines can be simple when you follow this guide.

Maybe you’ve already even thought about the type of AC you want! However, that may not necessarily be the best way to go about it. To make sure you don’t waste time, money, and effort installing a new AC that will only end up disappointing you, it helps to do some checking beforehand.

Your air conditioning unit's capacity must match the size of the area you want to cool.

Before you even start window-shopping, list down the following details to take with you on your next AC-scouting trip:

  • How much area you plan your AC to cover in square feet/square meters
  • The layout and construction of your room
  • Other heat sources in the area and near your AC, including appliances and potential occupants
  • How often and how long you plan to use your AC (a rough estimate of how many hours per day and how many days of the week should be fine)

When you’ve got all of that info prepared, it’s time to go hunting! Let’s take a look at some of the main aspects you should consider when choosing your AC.

Consideration 1: Cooling Capacity

Cooling capacity ought to be your number one consideration when selecting an AC. This is basically how powerful your AC is. It can also be called unit size or unit capacity and it’s measured in horsepower (HP).
The larger the size of the room you intend to put your AC in, the bigger your unit capacity should be. This is why it’s essential to accurately measure your home or workspace’s dimensions and then compare it to the unit size or HP of the AC you’re interested in. If your AC’s HP isn’t sufficient for the size of the room, not only will the room not cool down, but your AC will have to work harder in the attempt, resulting in hefty electricity bills.
Here’s how much HP is typically needed to cool rooms of different sizes:

This is how much horsepower your air conditiong unit must have for specific room sizes.

Consideration 2: The Room

In addition to room size, it also helps to know the features of the room because those also play a factor in cooling.


The properties of your window can affect how much harder your AC will have to work. Larger windows, especially those without tint, will let in more heat, and the more windows there are in the room, the more heat will be let in. If you have a room with multiple, large windows that let in a lot of sunlight, you may want an AC with a stronger cooling capacity, perhaps with an extra 0.5 HP.

You should also consider the location of the windows, if any, as the time of day affects when sunlight enters the room. If you have windows facing the east, you’ll experience more heat in the mornings because of the rising sun; if you have windows facing the west, you’ll experience more heat in the mid-late afternoon because of the setting sun.

On a final note, it would help to know when you plan to have your AC on. After all, window location won’t matter much if you aren’t going to be using your AC anyway (like if you’re working at an office).


Older houses, the kind that still use galvanized iron (GI) sheets for roofing, don’t offer much insulation, whereas newer houses tend to use bubble foil or polyethylene ceilings to repel heat. This plays a factor in cooling as well, as hotter homes can be more difficult to cool, and in contrast, well-insulated rooms require less power to cool. If the room in question doesn’t have adequate insulation, add another 0.5 HP to your cooling calculations.

The Purpose of the Room

This is probably the easiest factor to determine, as it follows your personal design choices. Knowing what you’re going to use the room for can help you figure out which AC is best-suited for your needs.

A bedroom air conditioner will have a different function compared to one in the living room.
  • Bedroom

Ideally, your AC shouldn’t directly overlook your bed as the direct air flow can make you too cold for comfort or even give you a sore throat upon waking up. You may want to place it to the side of the head of your bed, or choose an AC with adjustable vents or built-in air swings.

  • Living room

Unlike bedrooms, you’ll probably want to place your AC where its direct airflow will hit you and the rest of your family or guests. Interestingly, some modern ACs have smart functions that can direct air flow straight to where the remote control is, so you can have better control over where the cold air goes.

Consideration 3: Heat Load

Various factors can play a part in determining the overall temperature of your space.

As mentioned earlier, sunlight can heat up your home as it passes directly through your windows or indirectly through your roof. However, heat can also come from within your home. Home and kitchen appliances such as computers, TVs, refrigerators, and lights all generate some measure of heat, and these compete with your AC’s ability to cool the room down, especially if they’re all on at the same time.

In fact, if you install an AC next to a particularly-strong light bulb or heat-producing device, its sensors may not be able to accurately detect the actual temperature changes of the entire room and force it to work harder than necessary. If you feel like the room in question has a lot of heat sources, you may want to choose an AC with more HP than the room-size-to-HP table suggests.

Another factor is the human element: how many occupants do you foresee staying in the room regularly? We as humans naturally produce body heat, so the more people in a room there are, the hotter it will be. (If you’ve ever been in a crowded room, a concert, or full elevator, you should know how stuffy it can feel!) If you expect two or more people to occupy a room regularly, you should add an additional 0.5 HP of cooling power to your calculations for every two additional occupants.

Consideration 4: Usage Habits

This is where personal preferences and habits come into play, as they may change which AC you’ll want.

If you’re going to be out of the home for most of the day, you could opt to choose an AC with more HP than necessary so it cools your room more quickly. After all, if you’re spending less time in the room than out of it, you might as well make it comfortable as quickly as possible!

Different types of aircon units have different applications. Choose the one that suits your needs.

If you’re choosing an AC for a room, whether at home or at the office, that will be occupied throughout the day, you’ll want a high level of efficiency. That means choosing an AC with the right cooling capacity for the size of the room as well as an AC with a high level of efficiency. This is usually displayed in the Energy Efficiency Ratio (EER). Thus, for rooms that intend to be cooled for 8 or more hours per day, you may want to invest in an AC that uses less energy or an inverter AC that has the technology to reduce the amount of energy spent due to on-and-off cycles. This will lead to more savings in the long run.

When it comes to choosing an AC for any space, be it your home or workplace, doing the due diligence of checking not just the specs of the ACs but the room’s properties as well can pay off in spades. After all, an informed choice is usually the better choice, and one that can give you the best cooling performance for the job: keeping you and your family (or coworkers) healthy, happy, and comfortable.

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