Energy Efficiency and Air Conditioners: Central Units, Window Units, and Tax Credits
Air conditioners work by taking heat from your house and rejecting it to the atmosphere by way of a refrigerant. The warm air from your house is absorbed by the refrigerant, changing it from a liquid state to a gaseous state. The refrigerant then passes through the compressor that puts the gas under high pressure, adding a high amount of heat to the refrigerant. The superheated refrigerant then passes through the condenser, which is outside you home, where its heat is rejected to the atmosphere. Because the refrigerant loses so much heat, it turns back to a liquid at a very low temperature. This low-temperature refrigerant liquid then enters your home to absorb heat from the warm air in the room and the process starts over again.
For home air conditioning, you can choose between central air conditioners or window air conditioners. Each one has its own advantages. The air conditioner’s efficiency is measured by the EER and SEER. The higher the EER and SEER rating, the more efficient the air conditioner.
Central Air Conditioners
Central air conditioners can air condition an entire house, and are ducted for better air distribution and control. They are usually more energy efficient than window air conditioning units. Even though central air conditioners can be more expensive to buy than window units, the cost difference will be paid back over the life of the product with lower electricity bills and better cooling distribution in your home. The Energy Star website has a list of very efficient central air conditioner brands and models to choose from.
Window Air Conditioners
Window air conditioners are the most inexpensive air conditioning alternative to cool a room. The advantages of them are that they are a lot easier to install and a lot more inexpensive to buy. You would have to get several of these for your home to replace a central air conditioning system, but they would still be cheaper. They tend to be most energy inefficient and have much lower cooling capacities. Maintenance requirements would also have a homeowner changing several air filters a year, instead of just one with a central air conditioner. Nevertheless, the Energy Star website has a list of the more efficient windows units.
The American Recovery and Reinvestment Act of 2009 introduced energy efficiency tax credits that included central air conditioners. To qualify, package central air-conditioning systems must have an EER greater than 12 or an SEER greater than 14 for a federal tax credit of $300. Unfortunately, federal tax credits for energy efficient air conditioners expired on December 31, 2011 and have not been renewed for 2012. It is possible that they can be re-instated in the future, but as of now, no new legislation has been passed. But you can still get a 30% federal tax credit for using geothermal heat pumps.