Air Conditioner Buying Guide


Living in Malaysia, having air conditioner has become a necessity. In fact, this previous luxury has become a common item in almost all households that can afford it. Although there are many choices for air-conditioner, not many know how to buy one. Individuals end up buying the cheapest unit and this could result in higher energy consumption and frequent breakdowns. This article will give a guide on how to buy an air-conditioner for your home and the meaning of some phrases used in air-con shopping.


There are many different types of air-con in the market today so this article will limit to those commonly found in domestic houses. There are commonly 3 types of air-con to choose from, window, portable and split.


Window air conditioners are the old air-con units that you can find in old buildings. It can be found at window sills and is a bulky equipment that can power a room. Although being most affordable, it can be difficult to remove them and reinstall again. Also, it can only cool down a small room and usually can be noisy.


Portable air conditioners are the air-con units that can be moved around and acts like a deluxe portable cooling fan. These units are intended for homes in which window configurations or building regulations prevent installation. Also, air-con units are great to be used for home events where there is a big garden space. However, these units are costly, consuming more energy and noisier.


Split air conditioners are the most common in Malaysian households, being the sleek unit that is mounted at high wall level.  This one, although the costliest, has the most cooling power, is easy to install and use. The unit has low noise levels and needs a compressor outside the house. Much like regulating hot air and turning it into the cold air inside rooms.


Air conditioners have motors that drive the revolution of compressors. It helps to determine the level of cooling at either a constant speed or constant temperature. There are two types, which is inverted and non-inverted.

Inverted type air-con enables different speeds that automatically adjusts to meet an ideal set temperature. When the room condition reaches the desired temperature, the motor speed reduces thus requiring lesser power and resulting in lesser energy. It is an eco-friendly option and it is advisable to have in the long term, despite its expensive buying price.

Likewise, a Non-inverted air-con has motors that can either be switched off or on. Once the desired temperature is met, the motor shuts off. When the room temperature falls below the desired level, the motor functions again. This method lacks the energy efficiency, having to stop constantly and start again to maintain desired room temperature. Although a cheaper buy, the electric bill is more expensive in the long run.

Things to consider

There are also other aspects to consider when buying an air conditioner.

1. Horsepower (HP)

When buying an air-con, it is good to estimate the air-con suitability for the setting of the room. Air-cons have different compressor sizes and capacities. Being the heart of the cooling cycle, the compressor is measured in HP. Bigger HP equals to bigger cooling capabilities. 1HP would approximately equal to 746W(Watt) or 0.746KW(Kilo-watt). Home owners need to identify how many HP is necessary to avoid expensive costs in the long term. A compressor with 1HP capacity is able to remove approximately 9000 BTU/hr of heat.

2. British Thermal Unit (BTU)

BTU measures the amount of heat necessary to raise the temperature of 1 pound (0.45 kg) of water 1°F (0.56 °C). As compressors regulate temperatures through turning hot air into cold air, BTU is useful to know how quickly the room can cool down. 1 BTU equals to 1,055 joules. A normal window air conditioner rates approximately at 10,000 BTU. However, a higher BTU number does not equal to a long lasting and better functioning unit. This is because air-cons have cooling cycles, which a bigger BTU, might pose a problem as trying to lower the room temperature constantly can result in a shortened life span. Here’s a table below to help determine which BTU air-con to room size needed.

Room Size BTU’s Needed Room Size BTU’s Needed
150 sq. ft. 5,000 BTU’s 700 sq. ft. 14,000 BTU’s
250 sq. ft. 6,000 BTU’s 1,000 sq. ft. 18,000 BTU’s
300 sq. ft. 7,000 BTU’s 1,200 sq. ft. 21,000 BTU’s
350 sq. ft. 8,000 BTU’s 1,400 sq. ft. 23,000 BTU’s
400 sq. ft. 9,000 BTU’s 1,600 sq. ft. 25,000 BTU’s
450 sq. ft. 10,000 BTU’s 1,900 sq. ft. 28,000 BTU’s
550 sq. ft. 12,000 BTU’s 2,700 sq. ft. 36,000 BTU’s

Source: Compact Alliance

3. Room Size

When purchasing an air-con, research first the size of the room and the position of the room. The room position plays a role because rooms facing the west will have very strong sunlight in the afternoon and evening, which requires a more powerful air-con unit or more than 10%. If the house is fully shaded, it can even reduce the capacity by 10%. Also, the room size determines what HP and BTU are needed for the air-con. If the room is a small bedroom of 150 ft², a small 1HP air-con would work whereas the large 800 ft² room would require a 2.5HP air-con. It depends on certain situations as well, from the number of house occupants to whether the house is insulated or not. However, a general formula would be like one below

A + B = Btu / Hr

A = (Room Width (Feet) x Room Length (Feet) x 50)

B = (No of People x 500)

4. Energy Efficient Ratio (EER)

EER measures of how efficient a cooling system will operate when the outdoor temperature is at a specific level. It is measured in the ratio of cooling capacity of the unit per input power. The higher the EER, the more efficient the unit. Calculating EER is simple,

BTU/ Watts

For example, a 12,000 BTU air con consumes 1,500 watts, its EER is 8.

According to the United Nations Development Programme, the Sustainable Energy Development Authority of Malaysia (SEDA) emphasizes on EER units and those that are energy saving. SEDA informs that households could save RM277.42 annually for an air-con unit using a 5-star energy air-conditioners. It might cost you more at the beginning but you will save for the rest of the air-conditioner’s lifetime.


Overall, air-cons are useful and becoming a necessity in this lifetime. Depending on the room size, its exposure to heat, and primary function of the room, the cooling capacity of the air conditioner needed varies. Check out websites like Compact Alliance or other websites that enable one to calculate estimations.

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  1. Dave Miller

    Hey, I’m a HVAC technician and I noticed that you link to a BTU calculator on page, I have made a similar calculator based on more standardized and up to date calculations, meaning it’s essentially more accurate.

    Would you consider trying it out and possibly adding it as a reference? Here it is:

    I can also share the post to my following – via newsletter and Facebook, perhaps we can even collaborate in some other way, I often do guest posts and would love to work with you!

    Thanks in advance,

    Dave Miller

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