Room Air Conditioners

Air conditioners, Heating and cooling

A room air conditioner (RAC) cools the air, removes humidity, circulates air, filters out dust, and, in some cases, also provides heating. Although most RACs are designed for the residential market, they’re used for cooling in about 20% of commercial buildings. Building operators and managers purchase RACs for various reasons:

  • They want to cool selected rooms in an otherwise uncooled building
  • It isn’t feasible to install central cooling in the building
  • They want to completely isolate one room from another (for example, to avoid mixing air between rooms, to give each room control complete autonomy, or to be able to bill each room separately)
  • They want to replace a failed RAC

Commercial and industrial RAC consumers often waste money by not paying attention to efficiency ratings. New RACs in the US cost from about $200 to over $1,000 and have energy efficiency ratios (EERs) that range from 8.0 to 12.0. More-efficient units are often, but not always, more expensive than less-efficient units are. Smart consumers can save money in the long run by accounting for both initial cost and operating cost and then selecting the unit with the lowest lifecycle cost.

What are the options?

  • Most RACs in North America are installed in windows. Basic window models are used in regular, double-hung windows up to 40 inches wide and can be installed by the user.
  • Special-application models are cooling-only units used in narrow, vertical windows. Installation usually requires removal of a window panel.
  • Through-the-wall models are installed in an outside wall, usually during construction or remodeling, and generally require an experienced installer.
  • Some manufacturers, including Carrier and Fedders, offer portable units that roll on wheels and cool a single room (up to about 450 square feet in some cases). The exhaust hose vents out a window equipped with the manufacturer’s sash kit.

RACs of the same capacity are available with a range of efficiencies. The current US federal standard requires manufacturers to produce equipment at minimum efficiencies, as specified on the US Department of Energy’s Appliance and Equipment Standards Program page.

How to make the best choice

Select the right size An undersized unit won’t be able to cool a large room, while an oversized unit will cycle on and off frequently, increasing electricity consumption and decreasing the unit’s overall efficiency. An oversized unit may also cycle off too quickly to extract sufficient humidity from the air. You can calculate appropriate size yourself, have an HVAC contractor do the calculation for you, or use figure 1 to estimate the capacity based on the room’s area.

Figure 1: How to estimate capacity for an RAC

Rules of thumb for estimating air conditioner size vary by manufacturer. This example from Carrier includes the following suggestions for adjustments: If a room is heavily shaded, reduce capacity by 10%; if the room is sunny, increase by 10%; and if the unit is in a kitchen, increase capacity by 4,000 Btu/hour.
Figure 1: How to estimate capacity for an RAC

A unit’s efficiency affects its operating cost In the US and Canada, energy labels that display the EER must appear on RACs. Other factors being equal, a higher EER leads to higher energy efficiency—and lower operating costs (figure 2). Energy labels also indicate the expected energy cost and show how a product compares to the least- and most-efficient models available.

Figure 2: Operating cost for a 10,000 Btu/hour RAC

Savings from higher-efficiency RACs are more substantial when operating hours are longer.
Figure 2: Operating cost for 10,000 Btu/hour room air conditioner

Energy Star established an efficiency specification that’s higher than the federal standards. RACs that meet these specifications are awarded the Energy Star label, which helps consumers readily identify high-efficiency products. Visit the Energy Star Room Air Conditioner web page to check the product list for models you’re considering. This site can also help you calculate the right size unit for your application.

The Consortium for Energy Efficiency offers a program known as the Super-Efficient Home Appliances Initiative for Room Air Conditioners (PDF). The initiative’s goal is to encourage the use of high-efficiency RACs. As of January 2017, the minimum EER requirements for RACs that qualify for the initiative range from 9.9 to 12.0, depending on their size.

Determine which unit is most cost-effective Although you’ll want an efficient air conditioner, you may not need the most efficient one on the market, especially if you live in an arid climate with few months of cooling needs. As you compare models, consider both the initial price and annual-operating costs so you can determine the life cycle cost. If the annual-operating-cost savings offset the additional cost of the more efficient unit, the more efficient unit will be the better buy.

Here are some other issues to keep in mind as you’re shopping:

  • Look for an “energy-saver” switch. The energy-saver switch causes the air conditioner’s fan and compressor to cycle on and off together, reducing energy use.
  • Verify that you’ll get good moisture removal if you live in a humid climate. Manufacturers label the dehumidifying capacity of RACs according to moisture removal in pints/hour. An HVAC contractor can calculate how much dehumidifying capacity you’ll need. Be aware that increased efficiency can decrease dehumidification capacity.
  • Listen to the unit while it’s running. All RACs make some noise, but levels vary. Listen to models while they’re running, if possible, and check independent consumer guides for information on noise levels of the units you’re considering. ConsumerSearch has an Air Conditioner Reviews web page with ratings of RACs from 5,000 to 15,000 Btu and includes noise among its test categories.

What’s on the horizon?

In the future, new federal standards will likely drive RAC efficiency levels higher. A change to the federal standard may also affect the Energy Star program. Look for efficiencies to slowly increase as manufacturers continue to incorporate better compressors, heat exchangers, and fan motors into their products.

Who are the manufacturers?

As with other appliances, a single manufacturer may make different brands of RACs. The most prominent North American manufacturers are:

Neither this list nor any mention of a specific vendor or product constitutes an endorsement or recommendation by E Source, nor does any content the Business Energy Advisor constitute an endorsement or recommendation, explicit or otherwise, of your service provider’s various technology-related programs.

All content copyright © 1986-2020 E Source Companies LLC. All rights reserved.