Horsepower, BTU’s, Kilowatts, Square Meters and more – know the Air Conditioning Lingo

Guides — By Jonathan on March 29, 2010 at 7:34 am

You may have seen these terms posted on the box your air conditioner came in, or maybe you paid a bit of attention to the air conditioning repair man when he was telling you what the problem was. Heck, you may just be curious – and that’s good. Knowing air conditioning lingo could help improve your living conditions, and even save you a bit of money. Learning these could be a small time investment that just makes cents.

To Portable or not to Portable, that is the question

If you don’t have an in home air conditioning system, chances are you may have seen, or may be interested in buying a portable one. These don’t cool quite as well as a home unit, but they make up for this in versatility. Maybe you don’t need your whole house cooled. Maybe you have a small room or apartment that just doesn’t require a big ol’ air conditioning unit.

But which portable air conditioner should I pick? Well, they all have different functions, and as a general rule, you’ll get what you pay for. More specifically, though, the types can be broken down into:

Evaporative: Evaporative units are one of the cheaper units you can buy. This doesn’t make them a poor choice by any means. These air conditioners evaporate water and then pull fresh, outside air through the evaporated water. The downside to this is that the water doesn’t fill itself – that’s your job.
Single Hosed: This unit will draw in air and push it through a refrigerant area, where it will then be pushed back out to cool the room. The hose is then used to vent out excess hot air.
Double Hosed: These work similarly to the single hose units, however, they are a bit more powerful. Because of this added power, the second hose is necessary – it allows the unit to pull even more air to be cooled.
Heat and Cool Units / Reverse Cycle: These air conditioners don’t just provide you with cool air, but they provide heat too! They do this by doing the exact opposite of normal air conditioners. Where the others blow warm air out, these will suck it in. They sometimes have dehumidifiers with them, which will give you added control over the room’s humidity. Because they can do so much, they are often more expensive than the previously mentioned types.

These units will generally have filters (like home air conditioning units) and a drip tray (this collects excess moisture) that you need to occasionally empty. Filters need to be cleaned about once every two months to keep the air flowing and clean.

Now that you know the types, it’s important to find the correct energy requirements.

Kilowatts(kW) and BTU’s: These determine the amount of energy (electricity) used to power your air conditioning unit. Depending on the part of the world you live in, it is going to be either Kilowatts(kW) or BTU’s. The more energy your air conditioner uses, the cooler the area will become, and the more money it will cost to run the sucker.

However, if your air conditioning unit does not use enough energy, you will end up with a room that is not being cooled. Overworking the air conditioner, on the other hand, will just cost more money, and may even lead to it breaking (and you just bought it, too!). Because of this, it is important that you know how much energy it takes to cool an area. This way you aren’t wasting money, or over cooling/dampening the room.

A good rule of thumb is 80 watts (.080kW) per square meter for bedrooms, while for a living room you’ll want to go for 125 watts (.125kW) per square meter. That means if your bedroom is approximately six square meters, you’ll want to have an air conditioning unit running at about 480 watts (.48kW). For those using BTU’s, one watt is the equivalent of about 3.4 BTU’s. So you’re going to want to run about 272 BTU’s per square meter for bedrooms, and about 425 BTU’s per square meter for a living room area.

In addition to this, areas that get a lot of sunlight will require about 10% more energy to cool. So if your bedroom has a lot of windows like mine, tack on a bit more to your calculations.

A basic example might be:

Your browser may not support display of this image. If it was sunny in there, we’d then multiply .72 kilowatts by 1.1 (giving a total of .792 kilowatts to cool the room).

Horsepower: This is the speed which your air conditioner’s motor is running, and is also another way to find out how much energy is being used. 1 Horsepower (HP) is the equivalent of 2.55 kilowatts, or 2,550 watts, or 8,706 BTU.

Energy Efficiency Ratio (EER): You may have also seen this on the box. Just as you would assume, this lets you know how efficiently your unit is running. The higher the EER, the cooler the air conditioner will make your area. So, if the rating on your air conditioner is 4, then it won’t require quite as much energy to cool down the area as say, an air conditioner with a rating of only 2. The higher EER ones will generally cost more initially, but they’ll save you money in the long run.

But what does this have to do with me? Well intrepid reader, picking the correct air conditioner and running your air conditioning unit at the proper energy levels will save you a lot of money AND keep your area well cooled at the same time. So don’t run your air conditioner to death, and know what you’re going to buy before you go shopping at the store. It’ll all pay off in the long run!