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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

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

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.

DIY Success Story

“My neighbor complained for years that my 22-year-old AC unit was too noisy. To keep the peace, I decided to replace it. The old unit turned out to be a SEER 6. The new unit is a SEER 14 and very quiet. My neighbor is now happy and so am I—my summer electric bills are half of what I was spending with the old unit.”
Gene Hamolka

Tip 2: Switch to 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

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

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

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

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

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

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

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

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.

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Comments from DIY Community Members

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1 - 9 of 9 comments
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July 20, 7:07 PM [GMT -5]

Programmable thermostats do not always save money,especially with a heat pump in the winter months. A temperature difference of two degrees heating will cause the resistance electric heat to come on and wipe out any savings. You will wait for a long time before any heat pump will make up that difference with out resistance heat. Also,you might consider a spray water mist for your outdoor unit like they use out in the Southwestern states. Water vapor will move alot more heat than just air alone. Mine works great and runs up to 35% less! Note: you cannot use a Chlorinated water system for this spray system. It will eat the coil. You can use Saved rain water though.

July 07, 8:27 PM [GMT -5]

Plant trees! TFH should have had that as No. 1 in the first place, and furthermore, the other commenters missed the boat, also.

July 07, 8:17 PM [GMT -5]

I agree with BobbyCarl that there is the potential of raising the house humidity too high when using an evaporation cooler/swamp cooler. However, in many parts of the US the humidity is so low that adding moisture to the air in the house is a benefit. Our skin isn't nearly as dry. I monitor the humidity with a meter to keep it within an acceptable level.

Since the cooler brings outside air into the house there must be an escape path to vent the hotter air. I vent the air out through the garage and attic and thus slightly cool areas that wouldn't get any cooling when using our AC.

Coolers are less expensive to run than ACs.

July 07, 8:10 PM [GMT -5]

Just got done sealing all our ducts. It had made a HUGE difference in the comfort in the house...the upstairs bedrooms now are cool. We found a couple of ducts that weren't connected, and some rather large holes. Just make sure you don't buy the stuff called duct tape...it will self destruct after a couple of years. The roll I bought cost quite a bit. But my theory is that it will last for a long time. And I used the adhesive in a pail, and used a brush to spread it on. But it is very surprising what a difference it makes in the house's comfort.

June 08, 5:48 PM [GMT -5]

Swamp coolers increase the humidity level in the house. These high humidity levels can cause serious (and dangerous) mold growth. I do not recommend using evaporative coolers.

May 25, 12:00 PM [GMT -5]

I am phasing out all of my CFLs and replacing with LEDs. From initial checks it appears that CFL are a lot cheaper than LEDs, but this is not the real world data I have seen. I have had about 25% of my CFLs burn out in less than six months. I take the time to write the install date on my bulbs and I have tried a few manufacturers and never buy the "cheapest". CFLs also significantly dim after the initial install, and take a while to reach full light level.

I have yet to have an LED bulb need replacing and the light is amazing. You may need to consider an online store to get what you really want since it seems the home centers don't always carry the higher wattages. What I did was purchase some, and if they were not bright enough they were moved to places where I could do with less light.

This year I also got a new heat pump and high efficiency furnace. So that will be some energy savings.

Once my local utility provider called me and said "we just noticed that you seem to be using significantly less power than you used to". I guess maybe they thought I was doing something illegal before or something, but I just replied, "good for me".

June 21, 12:28 PM [GMT -5]

i don't understand why someone needs a programmable thermostat. i already turn my a/c temp up when i leave the house & turn it back down when i return. what's the advantage of (an expensive) programmable type?

July 23, 12:15 PM [GMT -5]

I agree Kim and believe a better alternative for CFL's although costly would be moving towards LED (light emitting diode) Technology. LED's draws very little power & produces very little heat. (efficient & savings in your pocket) Not to mention they last 50x longer so less garbage in landfills.

June 26, 1:07 PM [GMT -5]

I really like all of these suggestions except 1 - the CFL bulbs, and the reason comes from the fact they are made with mercury and can not be disposed of like an incandescent bulb. They are considered "Hazardous Waste" and must be handled as such, especially if they get broken. I believe if you are going to promote the use of this particular product you MUST take the responsibility to also warn of the hazards, the proper fixtures and usage and especially the way to handle the "hazardous waste" situation if they do get broken along with the fact they must be disposed in a certain manner when they "burn-out", as they should not just be "thrown away".

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