Cool down when it heats up

Tougher federal energy standards mean that today’s air conditioners are a lot more efficient than they used to be and cost less to operate, according to Consumer Reports.

That’s good news because up to 17 percent of a home’s energy budget goes to cooling. Central air conditioning is common in most parts of the country, but even homes that have it may want a window or portable unit to supplement cooling in a stuffy room or in a work shed, garage or other uncooled space.

If your cooling system is more than 10 years old, replacing it will bring immediate efficiency gains and drastically cut your costs. The window units on sale today meet strict standards that went into effect last summer. Manufacturers of central A/C systems will have to comply with even tighter energy standards by July 1, 2016. To test room A/Cs, Consumer Reports brought two dozen window air conditioners and a dozen portable units into its labs to put through its comfort evaluations. Here are the details:

Window A/Cs are worth a look. Small window units are the biggest sellers, and Consumer Reports found some to recommend that cooled the testing chamber quickly – and quietly. They include the GE AEM05LS ($210), a CR Best Buy, which cools 100 to 300 square feet.

“Portables” is a misnomer. Weighing between 51 and 82 pounds, portables aren’t easy to move. In its tests, Consumer Reports found that the dual-hose models were marginally better than the single-hose units. But neither provided the cooling oomph you might expect for the price or the BTU/hour listed on the box.

When shopping, Consumer Reports suggests keeping the following in mind:

Size it correctly. An air conditioner that’s too small won’t do a good job cooling a room. One that’s too big cools the area so quickly that it doesn’t have time to remove enough moisture, so it leaves you with a cold, clammy space.

Window air conditioners typically have cooling capacities ranging from 5,000 to 12,500 British Thermal Units (BTUs). But don’t buy by BTU alone. As a rule of thumb, an air conditioner needs 20 BTUs for each square foot of living space, but there are other considerations, such as the height of your ceiling and the size of your windows and doorways. Energy Star recommends that you add more capacity if the unit is in a sunny window or will be placed in a kitchen.

Note the noise. Models that scored Excellent or Very Good in the noise tests are so quiet that the only sound you might hear is the fan running. But air conditioners that scored Fair for noise could disturb light sleepers when set on low and are distracting on high.

Factor in the window location. Air conditioners generally do a better job blowing air in one direction than in the other. That can be a problem if your window isn’t centered on the wall. To uniformly cool a room, you’ll need to direct air to its center, so check whether your A/C needs to blow air to the right or to the left.

Check the warranty. Some air conditioners have longer warranties than others. When you’re buying a new unit, check the manufacturer’s website for information, then ask the retailer about the warranty for that model and brand.

Install it correctly. To get the most from your window air conditioner, install it right. Most units are intended for double-hung windows. If you have casement windows, you may want to consider a through-the-wall air conditioner. Make sure your window unit is level so it drains correctly. And move heat-generating devices such as a TV or lamp away from the unit.

Consider convenience. Make sure you can easily access the filter for cleaning, something you’ll be doing frequently to keep the unit in tip-top condition.

2015 Consumers Union Inc.