Most air conditioners have their capacity rated in British thermal units (Btu). A Btu is the amount of heat necessary to raise the temperature of 1 pound (0.45 kilograms) of water one degree Fahrenheit (0.56 degrees Celsius). One Btu equals 1,055 joules. In heating and cooling terms, one ton equals 12,000 Btu. A typical window air conditioner might be rated at 10,000 Btu. For comparison, a typical 2,000-square-foot (185.8 square meters) house might have a 5-ton (60,000-Btu) air conditioning system, implying that you might need perhaps 30 Btu per square foot. These are rough estimates. To size an air conditioner accurately for your specific application, you should contact an HVAC contractor. The energy efficiency rating (EER) of an air conditioner is its Btu rating over its wattage. As an example, if a 10,000-Btu air conditioner consumes 1,200 watts, its EER is 8.3 (10,000 Btu/1,200 watts). Obviously, you would like the EER to be as high as possible, but normally a higher EER is accompanied by a higher price.

Let's say you have a choice between two 10,000-Btu units. One has an EER of 8.3 and consumes 1,200 watts, and the other has an EER of 10 and consumes 1,000 watts. Let's also say that the price difference is $100. To determine the payback period on the more expensive unit, you need to know approximately how many hours per year you will be operating the air conditioner and how much a kilowatt-hour (kWh) costs in your area. Assuming you plan to use the air conditioner six hours a day for four months of the year, at a cost of $0.10/kWh. The difference in energy consumption between the two units is 200 watts. This means that every five hours the less expensive unit will consume one additional kWh (or $0.10) more than the more expensive unit. Let's do the math: With roughly 30 days in a month, you're operating the air conditioner: 4 months x 30 days per month x 6 hours per day = 720 hours [(720 hours x 200 watts) / (1000 watts/kilowatt)] x $0.10/kilowatt hours = $14.40

The more expensive air conditioning unit costs $100 more to purchase but less money to operate. In our example, it'll take seven years for the higher priced unit to break even.ANNIVERSARY EXTRA 25% OFF* Sign up today and activate awindow ac units nyc Common Questions about Window Air Conditionersair conditioning units for single room Published May 27, 2010 | small mobile air conditioning unitsUpdated August 5, 2015 A great way to beat the heat is by installing a window air conditioner in your home or office. Using individual air conditioners and heaters in your home can take the load off of your central heating and air conditioning system, providing you with significant energy savings over the course of a year.

Here are some frequently asked questions about window air conditioners and how you can use them in your home. Shop Air Conditioners & Heaters ▸ Will window air conditioners work in any window?Window air conditioners are built to fit multiple window types, including those that open vertically or horizontally. Many window air conditioners include adjustable panels, which help them expand to fit and seal most window openings. Be sure to measure your window and compare it to the air conditioner dimensions. What is a "SEER" rating?The SEER rating is a rating of window air conditioner efficiency. The higher the SEER rating, the more BTUs of cooling power your window air conditioner creates for every watt of power. SEER ratings are calculated by dividing the number of BTUs by the watts used per hour. How much energy does a window air conditioner use?To calculate your window air conditioner's energy use, divide the BTUs by the SEER rating. This gives you the watts per hour.

Divide that by 1,000 to get kilowatt hours (kWh), which is probably how your electric company calculates your energy bill. You can then multiply the kWh by your power company rate to learn your costs per hour. For example, a 12,000 BTU air conditioner with a SEER rating of 10 and a cost of 25 cents per kWh would calculate as follows: 12,000 BTUs / SEER 10 = 1,200 W = 1.2 kWh 1.2 kWh x $0.25 = $0.30 per hour to run your window air conditioner. At 8 hours a day for 125 days of summer, your window air conditioner will have an annual running cost of $300 a year. How often should I clean the air filter?Usually, window air conditioners need new filters every three months. If you live in an area with a lot of dust or pollen, you may want to replace it more frequently. Clogged air filters can impair the performance of your window air conditioner and increase your energy costs.Summer HVAC Maintenance Tips to Save Energy and MoneyActually, in terms of overall electricity usage in households, air conditioners use the most on a continual basis, followed by refrigerators.

But on a unit per hour basis, air conditioners are not that bad, even though they’ve been made the villain by the media. Broadcasters, in particular, are offering tips to households on how to cut down on energy consumption and the main suggestion is to set your air conditioner at 28 degrees centigrade. Because so many people, in particular the elderly, have fallen victim to heat stroke, no one is saying to turn off the air conditioner any more, but the general consensus is that the average air conditioner in the average home uses about 130 watts of energy and, overall, accounts for a bit less than a fourth of the summer electricity bill, which gives you some idea of the savings potential. What the media doesn’t say, according to an article in the most recent issue of Shukan Post, is that there is another appliance in your house that actually uses more electricity. A typical large screen (over 37 inches) LCD television set uses on average 220 watts, or 70 percent more energy than the air conditioner if both are being used continuously, but, of course, media companies aren’t going to suggest you turn off the TV because that would hurt their business.

And according to the Nomura Research Institute, since air conditioners work on something akin to fuzzy logic, they save more energy the longer you keep them on. The point is not to turn them off and on. If a room is, say 32 degrees and you turn on an air conditioner set to 27 degrees, it requires 800 watts right at the beginning, but after only a minute the energy consumption drops to 600 watts and then after 17 minutes it can drop to as low as 80 watts. What tends to be the concern of energy producers is not so much that households use their air conditioners, but rather that they don’t all turn them on at the same time. By the time an air conditioning unit is maintaining its set 27-degree temperature it may be using as little as 20 watts. The problem is, once you turn the air conditioner off, you have to start from zero again. Also, it should be noted that these figures are for rooms that are fully insulated. In comparison, three incandescent 60-watt light bulbs use 162 watts, continuously.

And TVs are worse: 220 watts isn’t a whole lot better than the old CRT TVs. Though LCD and plasma displays are touted as being more energy efficient by the industry, the comparisons are being made for equivalent screen area. For sure, a 28-inch CRT TV uses about 87 watts, and a same-size LCD screen only uses 42 watts, but the energy consumption increases exponentially from there. When you get to 40 inches, the LCD consumption jumps to 230 watts. And the whole point of flat screen TVs is that they take up less room and thus families are buying larger and larger ones. A 50-inch plasma screen uses 400 watts. Also, there’s a big difference in manufacturer specifications. Some makers are much more energy efficient than others, but the point is that the TV is not only using a lot more electricity than your aircon, it’s also heating up your room, making more work for your aircon. Even when the TV is on standby it’s consuming about 3 watts of power. So turn it off. There’s nothing to watch anyway.