Buying an air conditioner once considered a sign of luxury, is now becoming quite common in India. Many urban homes are equipped with air conditioners in one or more rooms. But everyone who owns an air conditioner knows that it comes at the cost of increasing electricity bills. Although cooling does take a lot of electricity but taking effective steps can surely get it down. One of the main things that can help is maintaining the right temperature for the air conditioners. For most people, air conditioner just throws cool air at the temperature one sets it at. But does it really work that way? In fact air conditioner during cooling process, takes the indoor air, cools it  by passing it through evaporator coil and throws it back in the room. It is quite opposite to how our good old air coolers used to work. Air coolers used to take outside air, cool it with water and throw it in. But air conditioners just work on internal air. If you set the thermostat at 18oC (64.5oF), does it mean that the air conditioner will cool the room faster than if set at 25oC (77oF)?

The thermostat just checks the temperature of the air inside the room and stops the compressor when the temperature reaches the desired level. This means that the compressor will work longer if the temperature is set to a lower level, i.e it will work more and use more electricity if temperature is set to 18oC (64.5oF) than if it is set to 25oC (77oF). This is because it will take less time for air to reach to 25oC (77oF) than 18oC (64.5oF) as the compressor is working with the same power or wattage. The air conditioner just blows the fan when the compressor stops and thermostat reaches the desired temperature level. At this stage the electricity consumption is only for the fan which is running and not for the compressor. The compressor will start again when the thermostat detects that the temperature has increased again from the levels that are set. Compressor is the most electricity consuming component of an air conditioner. There are 4 factors that influence the electricity load:

3) Thermal insulation of the room 4) Temperature setting of the air conditioner. If the difference between temperature desired and indoor/outdoor temperature is huge, then the air conditioner will need lot more electricity to cool the indoor air to desired temperature as the compressor will run for longer duration. If the temperature is set at 18oC (64.5oF) and the outdoor temperature is 38oC (100oF) then the electricity required will be lot more than when thermostat temperature is 24oC (75oF) and outdoor temperature is 38oC (100oF). As per study by ACEEE (American Council of Energy Efficiency Economy), increase of each oC can save 3-5% of units consumed. This can considerably bring down the units consumed per month in the electricity bill. Having said that, increase in temperature does not reduce the comfort level. In fact as per ASHRAE (American Society of Heating, Refrigerating and Air-Conditioning Engineers), the ideal temperature for thermal comfort is between 23.5oC (74.3oF) and 25.5oC (78oF) in summers (depends on several factors as listed on wikipedia).

Thus setting the temperature to 24oC (75.2oF) saves on electricity bill and provides good comfort. Using ceiling fans along with air conditioners can additionally help in increasing the thermostat temperature.how an ac unit work Setting an air conditioner to quick cool sets it’s temperature to 18 or 16 oC (64.4oF or 60.8oF) . how to service your ac unitThis means that the compressor stops only when indoor temperature reaches this level. cost of running ac all dayBut while coming down from 35 or 40 oC (95oF or 104oF) it would have surely crossed 24oC (75.2oF) which is a comfortable temperature. So using “Quick Cool” option does not help because more electricity is used to get the temperature down to 18oC (64.5oF) whereas compressor would have stopped in between if the temperature was set to 24oC (75.2oF) thereby consuming less electricity.

Old air conditioners without thermostat have high, medium and low cool options. As we learnt earlier that compressors of air conditioners work in binary mode (either they are on or off), an air conditioner without thermostat does not control air temperature. The high, medium and low options just changes the air conditioner fan speed. High means that air conditioner will throw more air and low means that the fan speed will be slow. The options do not change the temperature of the room, nor do they change the electricity consumption.There are ways to keep cool without turning on your air conditioner, but when the summer temperatures start busting the 90 (or 100!) degree mark daily, or the humidity makes it feel like you're swimming through a bowl of soup, sometimes air conditioning is a must. Stay cool and save money with these energy saving tips: 1. Keep the AC Lower at Night: During the night you don't require the same level of conscious cool. Try turning your AC down (so it is running less) during your sleep hours or, if your unit has one, utilize the "sleep mode" which lowers the output on a timer.

2. Use Window or Portable Units: If you aren't into cooling your whole home, try using a portable unit to cool just the area you'll be working in. They use up to 50% less energy than a larger central air unit would to cool off the same space. 3. Close Off Vents: The basement is traditionally the coolest room in the home, so try closing all the vents in the lower portion of your home. The cool air will slink down there naturally and by closing those vents, you're forcing all the air up top first, cooling as it comes down. 4. Service Your Unit: Some basic maintenance might be all your air conditioner needs, but most will greatly benefit from a good hosing out, especially if you're plagued with pesky trees like Cottonwoods that drop seeds which stick to the filters and make the unit work harder! 5. Check Your Ducts: Making sure the areas where your ducts run through parts of your home without air conditioning (like the attic) are properly insulated will keep the air coming in as cool as it can be.

Paying for half cool air isn't anyone's idea of money well spent! 6. Rearrange Your Furniture: Furniture that obstructs air conditioning vents means you could be cooling the back of a chair or the bottom side of your sofa and although it might appreciate the thought, we're pretty sure you'd rather have that chill for yourself instead. There are plastic pieces you can buy for your vents to help force air in the right direction, but the easiest way is to just rearrange your furniture, even if only temporarily. 7. Try 78 Degrees: 78 degrees is a good point for an air conditioner to run at its optimal performance level. Think of it as a car on cruise control headed across the flat Midwest prairie. It's not chugging along going uphill, it's just plugging away, steady as she goes. 8. Lighting: Turning lights off can help reduce your heat, but paying attention to how much light you let in from open windows can also play a significant role. Although it might seem neurotic to open and close your windows every day with the changing of the sun, it makes a huge difference in how much heat your a.c. is competing against.