Energy Saving Air Conditioning Tips

Cooling your home can be an expensive proposition, but there are things that every homeowner can do to help lower their electric bill when it comes to cooling their home each summer. On hot summer days, your home’s A/C system really gets a workout. Properly maintaining it on a regular basis will allow your A/C system to properly cool your home without breaking the bank.

Regular Maintenance

Regular maintenance of A/C systems is a very important chore. Regularly changing your air filter (or washing it, if it’s the washable-type) helps prevent unneeded wear on your A/C system, helps ensure a proper amount of air flow, and helps keep your home cleaner. Fiberglass woven air filters typically should be replaced monthly, however paper element “pleated” air filters are much better. The “pleated” type of air filter should last approximately 90 days and tends to better block the dust that the fiberglass filters allow to easily pass through. Also, a dirty or wet air filter prevents needed air flow through the A/C system which can lead to an iced-over indoor coil and little to no cooling of the home. I’ve seen a few iced-over coils in my home inspection travels; they are essentially an ice cube about 2′ in diameter that totally encapsulates the indoor coil. A home owner runs and runs the A/C and can’t figure out why the home doesn’t cool down and feels very humid.

Air conditioners work by moving heat energy from the home’s interior to the exterior using a refrigeration cycle; this is the same process that your refrigerator uses to cool it’s interior. Using an exterior compressor and condensing coil and an interior evaporator coil, the refrigerant (R-22 Freon in older units and R-410a in newer units) changes states (back and forth between liquid and gaseous states through the refrigeration cycle) to absorb heat from your home’s interior and release it to the home’s exterior via the exterior condensing coil. Since January 2020, the manufacture or import of Freon (R-22) is banned by Federal law, so if your older A/C or heat pump needs to be recharged, only recycled Freon (from old equipment taken out of service) will be available. According to several HVAC contractor’s that I’ve asked, recycled Freon is now in the neighborhood of $250~$500 per pound and will only go up as recycled Freon will be in even shorter supply. Most A/C units use approx. 6~9 lbs. of Freon. Budgeting for replacement of older A/C and heat pump equipment is recommended. Learn more by reading my “The End Of Freon (R-22).. And Soon Puron (R-410a)” article. Also, modern cooling equipment has higher SEER ratings compared to older equipment. Seasonal Energy Efficiency Ratio is a rating describing the energy efficiency of an A/C system. The minimum per Federal Law is now 13 (for the mid-Atlantic states).

An A/C system that does not properly cool the home is often related to one of three issues: (1.) low refrigerant charge, (2). dirty air filter (preventing proper air flow through the system), or (3.) blocked air flow around the exterior compressor unit.

Having your A/C system serviced annually by a qualified HVAC professional is important. Just like a car, A/C systems can work more efficiently and tend to have fewer failures or expensive repairs when regularly serviced and maintained. When A/C and heat pump systems are serviced, the technician should check the system’s components such as inspection of the outdoor unit’s capacitor, clean the indoor (evaporator) coil (debris or dirt prevents this coil from functioning properly), check the system’s refrigerant charge, etc. to ensure all items meet manufacturer operation specifications and that the system is working properly and efficiently. A programmable thermostat can also help save energy dollars.

Ensure Proper Clearance Around The Outside Unit

Ensuring that there is at least 24” of clearance around the system’s exterior unit is also important. For proper operation, a good amount of air flow is necessary for reliable and efficient operation. A common issue that I run across during home inspections is vegetation in contact (or close contact) with the exterior unit. As part of regular exterior maintenance, I recommend trimming vegetation that is growing within 24” of the outside unit. This may need to be done a few times per year. Also, there should be at least 6′ of clearance above your compressor unit (some manufacturers require at least 8′).

This A/C unit has vegetation growing against it. This limits the amount of air flow around the unit which can, therefore, also prevent proper operation of the unit and possibly, a shorter life span. At least a 24″ clearance around the compressor unit is recommended. Also, the outside unit should be kept clean of lint, dirt, debris. If the outside unit’s perimeter coils are not clean, efficient heat transfer can’t occur meaning the system hasn’t work harder and longer in order to properly function.

This is a poor location for an A/C or heat pump compressor installation due to the deck above the unit. Generally, at least 6′ of vertical clearance should exist above the compressor for proper operation.

The below photo is a thermal image of a central A/C system’s outdoor unit while operating. It shows an even heat distribution pattern on the perimeter condensing coil and is one indicator that the system is properly functioning.

What Does A Home Inspector Do?

During a home inspection, assuming the exterior temperature is above 60° F for several hours, the home inspector will run the A/C system for a period of time (at least 25 minutes) to a ensure that the compressor unit has a normal sound, take temperature checks at a representative number of supply and return registers, and check the air filter. He will also report on any service records available indicating that the system has been professionally serviced within the past 12 months. If the exterior temperature is below 60° F, the A/C system should not be operated as this may damage the system. Likewise, in the event of a heat pump, the cool (A/C) mode will only be run if the outside temperature is above 60° F.

Properly Insulating Your Home

Besides maintaining the cooling system itself, ensuring that your home is properly insulated can save you money that would otherwise go into running your A/C system longer. A good thing about insulation is that it will save you money in heating and cooling seasons. The current attic insulation standard (code) in our area for a new home is now R-49 (minimum) as of Oct 2018. (read my article called “Attic Insulation”) If your home was built prior to 2006, the amount of insulation in your attic is very likely much less than this amount. Most older homes have low amounts of insulation and many have none. In most homes, however, adding insulation is relatively easy to do plus doing so can pay you back in lower energy bills by way of more efficient heating and cooling.

“R-value” is a material’s resistance to heat transfer through the material. The higher the R-value, the tougher it is for heat to pass through a material. Blown-in cellulose has an approx. R-value of 3.5 per inch. So, 14” of cellulose should provide about an R-49. Loose fill fiberglass has an approx. R-value of 2.5 per inch and fiberglass batt has an approx. R-value of 3 per inch. If installing additional insulation in your attic, make sure that needed ventilation, such as soffit venting, is not blocked by the insulation. I find insufficient attic/roof ventilation in many homes that I inspect. Cardboard or rigid foam baffles can be installed to allow for needed cool air flow into the attic at the soffit vents while still allowing a good amount of insulation. Blocking needed soffit vent air flow into the attic can lead to ice dams in the winter as well as a very hot attic in the summer. This can lead to an A/C system running a lot more than it needs to and a very hot attic (likely to exceed 140º F) can also lead to premature roof shingle wear.

In addition to sufficient attic insulation, make sure that the attic access location is also insulated. It makes no sense to properly insulate your attic only to leave the ceiling-mounted access panel or attic door uninsulated. An attic insulated with 14” of cellulose (corresponding to R-49) has only an effective R-value of about R-7 if the average-sized attic access panel (approx. 2.5′ x 2.5′ in size) lacks insulation. Heat is always looking for cooler areas to move to, so an uninsulated attic access panel or door can render the attic insulation nearly useless. Adding a piece of fiberglass batt or rigid insulation at this location is relatively easy to do and can lower your energy bills and increase interior comfort. Most attic pulldown ladders are rarely ever insulated. Their covers are only a piece of thin plywood and have a very low R-value; this is a common location for heat gain or loss. Installing weather stripping where the access panel or cover closes is also suggested.

Keeping Your Home’s Interior Humidity Low

Run a dehumidifier between May and September. High humidity levels cause your A/C system to work extra hard as it has to extract large amounts of moisture from the household air while it also tries to cool your home. High humidity also makes the air feel warmer. A dehumidifier will also help minimize basement dampness and possible mold as well as helping to minimize conditions right for insect/rodent infestation in your home.

Don’t air dry your wet laundry inside your home and clothes dryer vents should only discharge to the home’s exterior. I sometimes see homeowners venting their clothes dryers into the home or basement for unknown reasons. Doing either of these things fills your home with extra humidity as the clothes dry.

Running ceiling fans in the rooms that you are using can help take some load off your A/C since the fans will help make the rooms feel cooler. You won’t feel the need to drop your thermostat down a few more degrees. Running a ceiling fan consumes less electricity than an A/C unit.

Thermostat Placement

Heat-producing objects, such as TVs and lighting, should never be placed near thermostats. Doing so causes the thermostat to read an artificially high room temperature which leads to the home’s heating system not running very much and the A/C system to run longer than it needs to. This leads to an uncomfortably cooler home in the winter and wasted energy (and a cooler then desired home) in the summer. The photo to the right shows an HVAC thermostat located too close to a TV.

Help Limit Your Home’s Sun Exposure

Plant deciduous trees in your yard at the south and southwest sides of your home. When the trees grow large enough, their leaves will limit direct sunlight helping to cool your home. In winter, these deciduous trees will lose their leaves and allow the sun to shine through to your home to help heat it on the colder days.

Something also simple to do on hot days is to close your window blinds or shades or drapes, especially on the east, south, and west sides. Doing so will help keep the hot sun from coming in through windows.

Ensuring that all doors, windows, and other exterior openings are properly caulked or weather stripped helps prevent gaps that cold/hot air as well as insects and water can enter. Keep drapes and blinds closed over your south and west facing windows. This will help minimize thermal energy from entering your home during the warmest hours (typically between noon and 5pm) of the day. Since energy costs keep on rising, each one of these items can help put less wear on your wallet.

Give Your Supply And Return Registers Some Space

Something that may seem like common sense but should still be said anyway.. make sure your A/C supply and return registers aren’t blocked by furniture, boxes/stored items, drapes, etc. and that the registers are actually open. I seem to find a good number of homes that have registers blocked by furniture, for example. No wonder certain rooms are warm in the summer.

Change Electricity Suppliers

Something that all PA homeowners can also do it change their electricity supplier thanks to the PA Electric Choice Program. This program started in the 1990s and lets PA homeowners and businesses choose an alternate electricity supplier. Your local electric utility, such as PPL, MetEd, PennElec, etc. will still service your home or business, but the company that your utility actually buys your electricity from is your choice and you can easily save 25~35% (or more!!) off your electricity costs by using this easy-to-use, free PA program. You simply enter your zip code and the site will show you current electricity offers and also lets you know your utility’s ‘price to compare’ current price. Scan the options to find a cheaper price than you’re currently paying. I suggest always choosing a fixed-rate offer. Check out the program’s website: https://www.papowerswitch.com/ and start saving money on your electric bill today.

Here are some other similar energy-efficiency related articles:
Attic Insulation
Energy Saving Heating Tips

Matthew Steger is a Certified Level 1 Infrared Thermographer, an ASHI Certified Inspector (ACI), and an electrical engineer. He can be reached at matthew@thehomeinspectorsnotebook.com. No article, or portion thereof, may be reproduced or copied without prior written consent of Matthew Steger.