Air Conditioners

Air Conditioners

If your current air conditioner is more than eight years old, it’s time for a new one. Over the life of the product, the amount you’ll save in energy bills will more than likely exceed the cost of the new unit. An added bonus: for every kilowatt hour (kWh) of electricity you save, you prevent the release of 1.34 lbs. of carbon dioxide (CO2) from your power plant. Over a summer season, this could result in a CO2 reduction of several hundred pounds and energy savings of about $65, when compared to an older model. See Before You Buy below before investing in a new system.

 

The following are basic criteria to use when choosing a new unit:

 

Energy Star Rating

 

The Environmental Protection Agency’s “Energy Star” ratings indicate that an appliance is at least 10 percent more energy-efficient than the minimum federal standards.

 

ACEEE Rated

 

The nonprofit American Council for an Energy-Efficient Economy (ACEEE) recommends central air conditioners that represent manufacturers’ most efficient models. For maximum energy savings, ACEEE recommends purchasing units with a SEER of at least 14.5.

 

BTUs

 

The cooling capacity of an air conditioner is measured in British thermal units per hour (Btu/hr). A good rule of thumb is to multiply the square footage of the space by 10 and then add 4,000. A room that is 500 sq. ft. would require at least 9,000 BTUs/hr: (500 x 10) + 4,000 = 9,000. Make sure you get the right size model for your needs. Choosing an air conditioner that is either too large or too small creates an unnecessary energy drain.

 

SEER (Maximum)

 

Central air conditioner efficiency is rated by its Seasonal Energy-Efficiency Ratio (SEER). The federal SEER requirement is 13 or above, and Energy Star requires SEERs of 14 or above. The units listed in the table are series of appliances, designed to outfit homes of varying sizes. The SEERs listed represent those of the most efficient units in each series.

 

Before You Buy

 

Many government agencies are offering rebates and trade-ins of older models to encourage the purchase of energy-efficient units. Find out if your state energy office or local utility offers any such deals. You could end up saving $75 or more on your purchase.

 

Even so, the greenest method of cooling your home involves creative home design rather than an energy-hogging appliance (get “The Back Story” about air-conditioning’s environmental impacts here). According to the Rocky Mountain Institute, about 50 percent of all electricity used in the United States during peak summer months is devoted to powering air conditioners. So before you start your search for a new, more efficient unit, consider the following simple home improvements:

 

Buy a ceiling fan or window box fan.

 

If you live in a dry climate, install a whole-house fan in your attic; it consumes one-tenth as much power as an air conditioner.

 

Close your blinds and windows during peak sunlight/heat hours and open your windows at night. Circulate cooler evening air into your house using fans.

 

Plant shade trees or trellised vines on the western and eastern sides of your home to reduce heat absorption.

Use energy-efficient landscaping to help cool your home’s exterior. Dense clusters of plants and bushes close to a home’s exterior walls have a greater cooling effect.

 

Install awnings and roof overhangs.

 

Add light-colored, textured or reflective roof and wall materials.

 

Choose energy-efficient indoor lighting and appliances to reduce the amount of indoor waste heat produced by these devices.

 

Seal and caulk walls and windows to prevent cold-air leaks.

 

Add low-emittance (low-E) glazing to windows to prevent heat transfer.

 

Shopping and Usage Tips

 

Avoid buying a used air conditioner or attempting to fix an older model. Unless it is a fairly new unit, the upfront savings will end up costing you more in higher energy bills, not to mention the negative impact on the planet in the form of increased CO2 emissions.

 

If you live in a very humid climate, look for models that are good at removing moisture. Because keeping condenser coils warmer improves efficiency, some high-efficiency models may not dehumidify as well as less efficient models. Manufacturers usually report the rate of water removal in pints per hour. Compare the rates of various energy-efficient models to find the best one for your needs, and consider adding a carbon filter to reduce humidity.

 

At the store, compare the energy consumption and usage costs of one model to another using the yellow “EnergyGuide” label on the product.

 

When determining your BTU needs, consider your local climate (both heat and humidity), window placement and the average heat level of the space directly above the room you want to cool, whether it’s your roof or a neighbor’s apartment. For a more accurate assessment, use the free sizing worksheet on Consumer Reports’ web site, www.consumerreports.org, where you can input various factors to calculate your BTU needs. Or see the BTU equivalency chart at www.energystar.gov.

 

When installing a central-air unit, hire a reliable contractor. Even the most efficient model will perform poorly if not installed correctly. Make sure your contractor calculates your required cooling capacity, and be sure to negotiate a maintenance plan with him/her as part of your contract. Check with your local Better Business Bureau and consumer-affairs office to find out if there have been any major complaints against a particular contractor before you sign, or consult the Air Conditioning Contractors of America (www.acca.org) to find a North American Technician Excellence (NATE) and Energy Star-certified contractor.

 

If you are replacing an old unit, make sure to safely dispose of the old one to prevent harmful refrigerants from entering landfills. When purchasing a new room air-conditioner, look for manufacturers and dealers that offer a take-back or end-of-life collection program. In general, they will safely dispose of your older model, often regardless of the maker, when you purchase one of their new appliances. Otherwise, contact the public works department in your city and ask about home-appliance recycling or refrigerant-recovery programs. Your contractor should be equipped with a refrigerant-recovery system, and a certified mechanic can safely remove refrigerants from the old equipment.

 

Usage Tips

 

After you purchase a new unit, improve its efficiency by doing the following:

 

Install a programmable thermostat so you can better control usage.

 

Set the to 78?F (or higher, particularly if you have a ceiling fan).

 

At night, use your air conditioner’s fan-only mode

 

Use the recirculate option instead of constantly cooling hot air from outdoors.

 

Turn the air conditioner off when you’re out and close vents in unused rooms.

 

Check your filter every month, especially during the summer when usage is high. Clean reusable filters, or replace disposable ones, every three months, or whenever they look dirty.

 

Have the contractor do regular inspections to ensure that there are no refrigerant or duct leaks, and clean the coils and drainage system.

 

What To Look For

 

If your current air conditioner is more than eight years old, it’s time for a new one. Over the life of the product, the amount you’ll save in energy bills will more than likely exceed the cost of the new unit. An added bonus: for every kilowatt hour (kWh) of electricity you save, you prevent the release of 1.34 lbs. of carbon dioxide (CO2) from your power plant. Over a summer season, this could result in a CO2 reduction of several hundred pounds and energy savings of about $65, when compared to an older model. See Before You Buy below before investing in a new air conditioner.

 

Many government agencies are offering rebates and trade-ins of older models to encourage the purchase of energy-efficient units. Find out if your state energy office or local utility offers any such deals. You could end up saving $75 or more on your purchase.

 

The following are basic criteria to use when choosing a new unit:

 

The Environmental Protection Agency’s “Energy Star” ratings indicate that an appliance is at least 10 percent more energy-efficient than the minimum federal standards.

 

Not only are most Consumer Reports rated models relatively energy-efficient, but they also outperform other models on the market. Consumer Reports scored models based on their comfort level, noise level and how well they start and restart in brownout conditions of high heat, high demand and reduced voltage. Models given the Consumer Reports “Best Buy” distinction have received high scores and come at a reasonable price.

 

The cooling capacity of an air-conditioner is measured in British thermal units per hour (Btu/hr). For a room air conditioner, a good rule of thumb is to multiply the square footage of the room by 10 and then add 4,000. A room that is 500 sq. ft. would require at least 9,000 BTUs/hr: (500 x 10) + 4,000 = 9,000. Make sure you get the right size model for your needs. Choosing an air conditioner that is either too large or too small creates an unnecessary energy drain.

 

A room air conditioner’s EER, or Energy-Efficiency Ratio, is the ratio of the cooling output divided by the unit’s power consumption. The higher the EER, the more efficient the model. Energy Star’s minimum EER requirements for a room air conditioner vary depending upon capacity, casement type and whether or not the model has louvered sides. For a model with louvered sides and a capacity of 14,000 to 19,000 BTU’s, the product must have an EER of at least 10.7.

 

Most room air conditioners come with pre-installed, reusable electrostatic filters. In some systems, those filters are treated with antimicrobials such as triclosan, which may be released into rivers and streams during manufacture, harming aquatic life. If purchasing a unit with an antimicrobial filter, ask the manufacturer (or retailer) to replace it with an untreated electrostatic filter. The latter may also be supplemented with a carbon filter that removes larger dust particles, odors and reduces humidity.

 

Before You Buy

The greenest method of cooling your home involves creative home design rather than an energy-hogging appliance (get The Back Story about air-conditioning’s environmental impacts here). According to the Rocky Mountain Institute, about 50 percent of all electricity used in the United States during peak summer months is devoted to powering air conditioners. So before you start your search for a new, more efficient unit, consider the following simple home improvements:

Buy a ceiling fan or window box fan.

If you live in a dry climate, install a whole-house fan in your attic; it consumes one-tenth as much power as an air conditioner.

Close your blinds and windows during peak sunlight/heat hours and open your windows at night. Circulate cooler evening air into your house using fans.

Plant shade trees or trellised vines on the western and eastern sides of your home to reduce heat absorption.

Use energy-efficient landscaping to help cool your home’s exterior. Dense clusters of plants and bushes close to a home’s exterior walls have a greater cooling effect.

Install awnings and roof overhangs.

Add light-colored, textured or reflective roof and wall materials.

Choose energy-efficient indoor lighting and appliances to reduce the amount of indoor waste heat produced by these devices.

Seal and caulk walls and windows to prevent cold-air leaks.

Add low-emittance (low-E) glazing to windows to prevent heat transfer.

 

Shopping and Usage Tips

Avoid buying a used air conditioner or attempting to fix an older model. Unless it is a fairly new unit, the upfront savings will end up costing you more in higher energy bills, not to mention the negative impact on the planet in the form of increased CO2 emissions. Plus, older window units may be fire hazards. As of July 2004, all units have safer plugs that automatically shut down power if they sense that the power cord has been damaged.

 

If you live in a very humid climate, look for models that are good at removing moisture. Because keeping condenser coils warmer improves efficiency, some high-efficiency models may not dehumidify as well as less efficient models. Manufacturers usually report the rate of water removal in pints per hour. Compare the rates of various energy-efficient models to find the best one for your needs, and consider adding a carbon filter to reduce humidity.

 

At the store, compare the energy consumption and usage costs of one model to another using the yellow “EnergyGuide” label on the product.

 

When determining your BTU needs, consider your local climate (both heat and humidity), window placement and the average heat level of the space directly above the room you want to cool, whether it’s your roof or a neighbor’s apartment. For a more accurate assessment, use the free sizing worksheet on Consumer Reports’ web site, www.consumerreports.org, where you can input various factors to calculate your BTU needs. Or see the BTU equivalency chart at www.energystar.gov.

 

If you are replacing an old unit, make sure to safely dispose of the old one to prevent harmful refrigerants from entering landfills. When purchasing a new room air-conditioner, look for manufacturers and dealers that offer a take-back or end-of-life collection program. In general, they will safely dispose of your older model, often regardless of the maker, when you purchase one of their new appliances. Otherwise, contact the public works department in your city and ask about home-appliance recycling or refrigerant-recovery programs.

 

Usage Tips

 

After you purchase a new unit, improve its efficiency by doing the following:

If your unit has a thermostat, set it to 78?F (or higher, particularly if you have a ceiling fan).

At night, use your air conditioner’s fan-only mode

Use the recirculate option instead of constantly cooling hot air from outdoors.

Turn the air conditioner off when you’re out.

Clean the filter often (biweekly or as needed), and where possible, hose down the back of the unit to remove debris that can clog cooling coils.

Make sure window models are installed as tightly as possible to prevent hot air from seeping in around the unit’s edges.

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