How to choose an air-conditioner

Thanks to an explosion of demand for air conditioners sweeping across Asia, there's no shortage of brands, models and features to consider. In fact, in addition to cooling, most units today dehumidify and filter air, making it more comfortable and cleaner. The type of air conditioner you pick, however, will depend not only on your budget, but what your needs are, as well as what part of the house you want to install it.

The space you have

Assuming you've decided to put an air conditioner into your bedroom or several rooms, you should consider the size of the rooms. If you are renovating your bedroom from scratch, it might be a good idea to get in an expert to give you suggestions on what type of air conditioner will suit you, where to place it, and what capacity is good. But if you are shopping on your own, do measure the volume of your room(s). You can do this by noting the width, height from floor to ceiling, and length, and multiplying all three figures.

Your cooling requirements

Know your capacity:
Once you've decided on the type of air conditioner to get, there are two technical specifications to heed.

BTU: Every air conditioner has a cooling capacity number in BTU or British thermal units per hour. The higher the value, the stronger the air conditioner is. Of course, the more the BTU, the costlier. So in short, bigger isn't always necessarily better. It would be good to get as close to the correct BTU as possible as too small a unit could leave you sweltering despite the air conditioning, while too big a unit could cost you more to cool your room. You will also need factor in other aspects like number of windows, whether your bedroom faces the sun, how insulated it is, if there are electronic devices in the room, and how many people share the room. Speak to the salesman in charge of the air-conditioning department for some practical advice. There are plenty of online calculators, including this worksheet to help you estimate just how powerful an air conditioner you need.

EER: EER or Energy Efficiency Ratio is another good indicator for measuring how energy efficient an air conditioner is at turning electricity into cooling. With utility cost on the rise, your monthly bill could be quite brutal if you plan to run your unit for long hours. So check the EER number. Generally, the higher the number, the more efficient the unit, the less it will cost to run.

Air-conditioner types:
Here's a quick look at some of the more popular types of air conditioners for your bedroom.

Window unit:
Typically a self-contained single unit, as its name implies, this sits within a window encasement with the cooler facing the room and the coils outside the window. Window units extract heat and moisture from the room, blows these outside, and returns cooled air to the room. There are three main types: Double-hung windows, sliding windows and casement windows.

Wall unit:
Similar to window units, this fits through a hole in the wall instead and are generally used to cool a single room. You will need a sleeve in your wall to support the weight.

Ductless, split system:
These are more popular in homes to cool multiple rooms or open areas. Typically more expensive than the wall or window units, this needs professional help to install as the compressor sits outside, while one or more indoor air conditioner outlets need to be mounted either on the walls or in the ceilings of the rooms.

Portable system:
As the name implies, these are portable upright units usually with wheels at the base. Hot air is vented through a hose attached to the unit, while condensation is recycled through the air or collected in a bucket or tray which will need to be emptied regularly. Portable units can be plugged into any normal mains and can cool a small room.

Other features:
There are loads of other bells and whistles you can opt for, though this will naturally add to the cost of the unit.

• Inverter technology: If you are going to on the aircon 24/7, an inverter may cost more initially, but will save on the electricity bill over time. This is because the inverter circuit regulates the rotational speed of the compressor to reduce the start-stop cycles, which in turn increases efficiency.
• Adjustable and oscillating louvers: These distribute the air more evenly and even let you direct the air where it's needed.
• Temperature range: If you live in a hot country like Singapore or Malaysia, check to see how low the temperature setting can go. Some air conditioners can only go down to 20 degrees Celsius which may not suit your needs. If possible, get one where the temperature can be raised or lowered incrementally by 1 degree Celsius for greater precision.
• Digital thermostat: Almost all air conditioners have a thermostat which is a temperature-sensitive switch that controls the air conditioner. However, an analog thermostat usually requires manual adjustments of the knob, whereas a digital thermostat can be easily set via a remote control and with greater precision.
• Digital timer: Most digital models would have a built-in timer which lets you program the unit to begin cooling at a time you specify, such as before you return home from work. Some even offer a seven-day timer which lets you program your air conditioning patterns over a seven-day time frame.
• Sleep mode: Some units have a sleep setting so that the unit goes into sleep mode and slows down the cooling process, saving energy and money. Some brands also have intelligent sleep modes that automatically adjust the room temperature and maintain the optimum skin condition during the various cycles of sleep.
• Fan speed settings: The more settings available, the more choices you have to accommodate varying needs.
• Anti-bacterial: Some brands now offer health-friendly models that kill both germs and fungus. Some have a carbon or ceramic deodorizer that removes bad smells and deodorize the air. Others use special filters that effectively break down dust, smoke and even pollen for asthma sufferers.
• Removable filters: Clean air is essential for efficient operation, and this requires cleaning the filters regularly. So look for ones that can be easily cleaned or removed. Some newer units may have an electrostatic filter available either as a standard or as an option. This filter is very useful for those with allergies as it will remove extremely small particles from the air.
• Restart delay: Air conditioners are not designed to be turned off and immediately back on. So if the power goes off accidentally, the restart delay function is a protective feature that prevents the heat pump from starting up again too soon after being switched off. It will safely start the air conditioner after a couple of minutes.

Your budget

Once you're ready with an idea of what you need, it's always good to research the Internet for recommendations and reviews based on the features you are considering. When you've settled on a brand and model you trust and want to get, check for store deals or discounts. Usually, appliance stores out in the suburbs offer better rates. Check also if the purchase price includes installation and delivery, and if not, how much more this would add to the total cost. Last but not least, remember to bring your room measurements along.