Home Energy Savings | June 3, 2016

How to Choose an Air Conditioner

Summer is the time for air conditioners in Texas. Two-thirds of all homes in the U.S. have air conditioners, according to Energy.gov, and air conditioners use about 5% of all the electricity produced in the country. That’s an annual cost of $11 billion to homeowners. In Texas, air conditioners account for 18% of home energy use, according to the U.S. Energy Information Administration.

The question, of course, is how to choose an air conditioner. Should you go with central air conditioning or a window air conditioner? And what’s the right air conditioner size for the area you want to cool? Here are some pointers to determine air conditioner sizing in order to keep cool all summer long.

Energy efficient air conditioners

It might be worth it to replace an air conditioner that is as few as 10 years old, Energy.gov notes, because today’s models generally save 20-40% of cooling energy costs.

When choosing an air conditioner, look for one with a higher seasonal energy efficiency ratio (SEER). SEER refers to the amount of energy needed to create a specific cooling output. Older models typically have SEER ratings of six or less.

As you think about how to choose an air conditioner, although air conditioner sizing is one important factor, it also helps to consider a model with an ENERGY STAR label. An ENERGY STAR air conditioner, like other other appliances with the ENERGY STAR label, meets certain federally mandated guidelines regarding energy efficiency. ENERGY STAR air conditioners use about 15% less energy than conventional air conditioners; on average, this could result in a savings of about $85 over the lifetime of the unit, according to Energy.gov. ENERGY STAR air conditioners also often have timers that enable you to have better temperature control and therefore use the minimum amount of energy needed to cool a room or home.

Choosing an air conditioner with an ENERGY STAR certification might also provide another financial saving: you could be eligible for federal tax credits. This year, the federal government renewed its energy efficiency tax credit incentive for a number of appliances, including central air conditioning. The credit for ENERGY STAR air conditioners that meet all the guidelines is $300.

How to choose an air conditioner

There are a number of variables beyond energy efficiency to consider when choosing an air conditioner. One of the first decisions is whether to go with room air conditioners or central air conditioners. If you want a compromise, you could choose a ductless, mini-split air conditioner.

Central Air Conditioner

Central air conditioners cool a home through a series of supply and return ducts. The supply ducts, or registers, carry the cooled air from the air conditioner into the home. This cooled air circulates through the home, growing gradually warmer, before flowing back to the central air conditioner for recooling.

Central air conditioners come either as a split-system or a packaged unit. In split-systems, the outdoor metal cabinet holds the condenser and compressor while an indoor unit holds the evaporator, according to Energy.gov. This indoor unit might, depending on the split system, also include a furnace or part of a heat pump. If your home already has a furnace but no air conditioner, a split system could be the most economical central air conditioner choice.

Packed air conditioner

Packaged air conditioners have all the parts in one cabinet, usually placed on a roof or on a concrete slab near the house foundation. In this form of central AC, the supply and return ducts come from inside through the exterior wall to the cabinet. Packaged air conditioners usually include heating, which eliminates the need for a separate furnace indoors.

Ductless mini-split conditioners come in handy because they can be retrofitted into homes without heating ducts (such as hot water heat, radiant panels and space heaters like wood). They can also work for room additions and small apartments.

They have two main components: an outdoor compressor/condenser and an indoor unit to handle the air. The two sections are linked by a conduit that connects the various cables and tubing.

Ductless Air Conditioner

One of the benefits to choosing an air conditioner like this is flexibility. They can be suspended from a ceiling, mounted into a drop ceiling or hung on a wall. Floor-standing models also exist. Some models can have as many as four indoor zones or rooms attached to one outdoor unit. Each can have its own thermostat, which enables you to better control energy usage. They are also fairly easy to install and, since they are ductless, they rarely have any of the energy losses that can come with ductwork. Energy.gov states that duct losses can account for more than 30% of energy consumption, especially if the ducts are in a space like an attic.

Choosing an air conditioner like this does have some disadvantages, though. Cost runs from $1,500-$2,000 per ton of cooling capacity. That’s about 30% more than central air conditioning systems, according to Energy.gov, and perhaps twice as much as window units of similar capacity.

Air conditioner sizing is another important variable when choosing an air conditioner. Simply put, air conditioner size matters. A room air conditioner that’s too big for an area will operate less efficiently than one that is the right size. This is because an AC that is oversized will cool a room to the set temperature before the room has been properly dehumidified. The result, Energy.gov states, is a room that feels clammy rather than cool and comfortable. An oversized or incorrectly ductless mini-split air conditioner, meanwhile, can result in short-cycling, which needlessly increases energy use and potentially increases costs as well. Correct air conditioner sizing is so critical that Energy.gov recommends having a professional evaluation to size central air conditioning systems and ductless mini-split air conditioners.

Energy saving air conditioning tips

You’ve made your air conditioner choice. Here are some tips from Michael Bluejay, aka Mr. Electricity, on how to save on your air conditioning energy costs.

  • Raise the temperature of your AC to 78 degrees. Bluejay says each degree you operate your air conditioner below 78 degrees increases your energy use by 3-4%.
  • Install ceiling fans. Fans can make you feel three to eight degrees cooler, which in turn means you can set your air conditioner at a higher temperature. (See prior tip.)
  • Make sure the ceiling fan is turned so that it’s blowing down, forcing air past your body, helping to cool you — and the room — down.
  • If you have central air conditioner, use a programmable thermostat that enables you to only cool the house when people are actually in it. For window air conditioners, use the timer that most units have.
  • Set the fan in your central air conditioning system to shut off at the same time as the compressor. This prevents the AC from circulating air; use fans instead for that purpose.
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