How to Save Energy and Cut Cooling Costs

Overview: Costs and savings

Staying cool is expensive. In a hot climate like Texas, the average family spends about $600 a year on cooling. In the Midwest, it’s about $300. But costs vary a lot within regions and even within a single neighborhood. Your home may cost $700 to keep cool while a similar home next door costs half that. This article will help you make your home the low-cost energy leader on the block. Our focus is on cutting cooling costs, but many of these tips will save you money on your heating too. We include upfront costs and payback for each of our tips, but the actual figures depend on your individual house, region, climate, living habits and electric rates.

Tip 1: Replace your old air conditioner

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Photo 1: Buy an efficient air conditioner

Paying higher upfront costs for the most efficient unit possible (SEER 14 or higher) makes sense in hot climates since the initial investment will be paid back in energy savings over time. It makes less sense in cooler climates.

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Close up

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Photo 2: Special disposal rules

Don’t do this at home. Contact your local waste management organization to dispose of your AC unit properly.

Replacing a 10-year-old window or central AC unit with an Energy Star model can cut your cooling costs by 30 to 50 percent and save you enough over the new unit’s lifetime to offset its purchase price. This is especially true if you live in a hot, humid climate. Central AC units are rated for efficiency according to their Seasonal Energy- Efficiency Ratio (SEER). Window units are rated according to their Energy-Efficiency Ratio (EER). The SEER/EER rating is listed on the Energy Guide label (below). The higher the number, the more efficient the unit. If you double your SEER (or EER), you can cut your AC operating costs in half. To find the rating on an older unit, check the data label or plug the model number into the online CEE-ARI database at < href="http://www.energystar.gov">energystar.gov on the Central Air Conditioners page. New units are required by law to have a SEER of at least 13 and an EER of 8. Central AC units manufactured from 1992 through 2005 have a SEER of about a 10, and older models are at 6 or 7.

COST: Window units range from $250 for 6,000 BTUs to $750 for 24,000 BTUs. Replacing an old central-air system typically costs about $3,000, but it can run as high as $10,000.

PAYBACK: The older your system and the more you use it, the larger your energy savings will be with a new unit. For example, replacing an ancient SEER 7 unit with a SEER 14.5 unit that costs $3,000 will save you about $700 a year and pay for itself in five years. Calculate your payback with the AC savings calculator at energystar.gov.

Online savings calculator

AC Shopping Tips

• Buy an Energy Star–rated central AC unit with a SEER of 14 or higher (especially if you use your AC a lot).
• Buy the right-size central AC unit by making sure your contractor performs a thorough cooling load analysis on your home. Too many contractors simply choose a unit that’s the same size as the old one. In many cases, the old one is oversized, so it wastes electricity.
• Replace the entire unit, not just the outside condenser. If you don’t replace the inside coil and/or blower fan, you won’t get the rated efficiency.
• Buy a unit with eco-friendly coolant (R41A “Puron”) since R22 (Freon) will be phased out of production in 2010. If you get stuck with an old Freon unit, recharging the system will be very expensive (not to mention environmentally harmful).
• Use the Energy Star savings calculator at energystar.gov to figure out whether it makes financial sense to replace your AC, and get a list of the most energy-efficient AC units.
• Check for local, state and federal rebates on higher efficiency units at dsireusa.org.
• If you live in the Southeastern United States, consider a heat pump, which moves air more efficiently than a conventional AC unit in areas with high humidity. If you live in the Southwest, consider an evaporative “swamp” cooler, which uses 75 percent less energy than conventional AC and costs about half as much to install. For more information, go to energystar.gov.

Tip 2: Switch to CFLs

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CFL in hanging fixture

Standard incandescent bulbs give off a lot more heat than CFLs.

You already know that compact fluorescent Light bulbs cut lighting costs, but they cut cooling costs too. That’s because, unlike incandescents, they give off very little heat. Ninety percent of the electricity used by an incandescent bulb is converted to heat rather than light. That extra heat means extra cooling expenses.

Online savings calculator COST: $3 per bulb. PAYBACK: Less than a year.

Tip 3: Install a programmable thermostat

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Mounting a programmable thermostat

Mounting a programmable thermostat is a simple DIY project. Follow the manufacturer’s instructions for programming it.

This is another easy upgrade that pays back quickly. Setting your cooling system four to six degrees warmer when you’re away at work or on vacation and automatically lowering it to 78 degrees when you’re home can cut 5 to 20 percent off your energy bill. This simple DIY project takes less than an hour.

COST: $50 to $150.

PAYBACK: About a year if you use it for both heating and cooling.

Tip 4: Clean or change AC filters monthly

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Check your AC/furnace filter

Dirty air filters slow airflow and make the blower fan and cooling system work extra hard.

Dirty air filters are the No. 1 cause of air conditioning breakdowns and they cost about 7 percent more in energy costs (or about $45 a year) in hot climates. Change central AC furnace filters monthly during the summer. Most window units have a removable filter behind the air inlet grille that you can take out and rinse monthly.

Tip 5: Fix leaks in AC ducting

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Seal forced air ducts

Use special foil tape to seal joints in cooling and heating ducts.

If your home was built in the past 10 years or so, it probably has well-sealed ductwork. But if you live in an older home, 10 to 40 percent of your cooling dollars is lost through gaps in the duct joints. This cool air is wasted when the ducts run through an attic, crawl space or basement. This can be a tough DIY project to do effectively since it takes a professional to test for leaks before and after the repairs. It you’re game for sealing the ducts yourself, examine your ductwork for cracks, splits or bad connections and feel for escaping air when your system is on. After you seal the leaks, keep the ducts cool by insulating them with R-6 or higher fiberglass duct wrap if they run through a hot attic.

COST: $300 to $1,000 for a professional to test and seal your heating and cooling ducts. DIY duct sealing costs $20 for a 60-yd. roll of aluminum tape and $5 for an 11-oz. tube of sealant.

PAYBACK: Two to four years for professional duct sealing and less than a year for DIY sealing.

Tip 6: Block out sun with window shades

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Install window film

Tinted or low-E window films are inexpensive and easy to install.

Roughly 30 percent of unwanted heat comes through your windows. Putting shades, insulating curtains or tinted window film on south- and west-facing windows can save you up to 7 percent, or $45, annually on cooling costs. The combination of shades and trees (see Tip 7) can lower indoor temps by 20 degrees on a hot day. Insulating curtains will save even more on both heating and cooling costs.

COST: Shades, $10 per window; low-E films, $5 per window; insulating curtains, $30 to $150 per window.

PAYBACK: One to four years depending on initial costs and where you live.

Tip 7: Keep cool with shade

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Shade trees and trellis

Use foliage to shade both the house and windows during the hot months.

Heather Down istockphoto

Cut AC costs through your own sweat equity by shading your house with trees, trellises and vines. Shading blocks direct sunlight through the roof and windows, which is responsible for about half of the heat gain in your home. Carefully positioned trees and horizontal trellises on the east and west sides can save up to 30 percent of a household’s energy consumption for heating and cooling. For an average household, that’s $100 to $250 in energy costs annually.

COST: Three 6-ft. trees, $900; DIY trellis, $50 (for a bare-bones version) up to $500 (for the deluxe model); vines for trellis, $50.

PAYBACK: On average, a well-designed landscape provides enough energy savings (heating and cooling) to return your initial investment in six to eight years.

Tip 8: Check your AC system’s efficiency

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Cooling test

The temperature difference between air at the supply and return grilles will tell you if your system is working efficiently.

To determine whether your air conditioner needs a tune-up, perform this easy test when your AC unit has been running for at least 15 minutes and the outdoor temp is above 80 degrees F. With a clean air filter in place, set a thermometer on the supply register that’s closest to the inside cooling equipment. Keep it there for five minutes and note the temperature. Do the same thing at the return vent. The air coming out should be 14 to 20 degrees cooler than the air going in. An air conditioner that’s not cooling to those levels could be low on refrigerant or have leaks. A unit cooling more than 20 degrees could have a severe blockage.

Tip 9: Use fans and raise your thermostat

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Use ceiling fans

Moving air keeps you cooler. You can set the thermostat higher while still feeling comfortable.

Hampton Bay

Ceiling fans can save you money by keeping you comfortable at higher thermostat settings. Each degree higher than 78 degrees will save you 5 to 10 percent on air conditioning costs. The moving air from a ceiling fan increases the amount of evaporation from your skin and helps cool you off.

Here are step-by-step instructions for installing a ceiling fan.

COST: Ranges from $50 to $1,000. Energy Star–rated fans are about 10 percent more efficient than standard ceiling fans and are usually in the $150 and above range.

PAYBACK: Depends on how high you set your thermostat and the cost of the fan. Could be as fast as three years or as long as 20 years.

Tip 10: Tune and clean your AC regularly

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Cleaning the condenser fins

Lift off the top to clean debris from the outside AC unit.

Frances Twitty istockphoto

A poorly maintained air conditioner uses 10 to 30 percent more energy and has a shorter life. Central AC compressors last on average about 10 to 12 years. Proper maintenance can extend that to 20 years. It’s important to have a professional tune, clean and check controls and refrigerant levels on your central AC system every two to three years. If your refrigerant needs recharging, this correction can improve efficiency by 20 percent. It’s also important to perform DIY maintenance each year. Several contractors told us that 90 percent of air-conditioner failures are caused by a lack of maintenance.

COST: Professionally cleaning and servicing a central air conditioner costs $100 to $250.

PAYBACK: This depends on the age of the unit and how dirty it is. If you haven’t had your AC unit serviced in several years, having a professional do a thorough tune-up could pay for itself in less than a year and extend the life of your unit.