July 2008

The Cost of Keeping Cool: Without Scaring Your Neighbors

Author: Jim McCaffrey

Air conditioning and your electric bill

Demand for electricity is increasing in South Carolina. The increases are driven primarily by population growth- one estimate is +25% over 12 years by 2010. Utilities and distribution companies forecast increased needs in their service areas and plan additional power generation to meet them. Plus they promote consumer awareness and conservation measures.

Palmetto Electric met a record peak summer demand of 387 megawatts on August 9, 2007. If Santee Cooper had been forced to buy emergency power off the grid, the cost of electricity could easily have been five-50 times its normal generating costs, if available at all.

What has this to do with air conditioning and the Hilton Head Island/Bluffton area? This growing market is one of several depending on Palmetto Electric’s ability to deliver temporary additional power to meet seasonal visitor peaks and very hot summer temperatures. While others are responsible to provide electricity, consumers should ask, “What can we do to reduce our needs and our electric bills at the same time?” The answer is: Use electricity wisely.

HVAC (Heating, Ventilation and Air-Conditioning) systems cause up to 70% of the energy reflected on your electric bill. To lower costs: • Keep thermostats at the highest “cool” setting you can live with. (Every two degrees cooler can add five percent to cooling costs.) • Keep doors and windows closed and shaded. • Seal up outside leaks. • Turn off the attic power ventilator, because it draws cooled air up from inside and can pull outside humidity in. • Add insulation in the attic and wrap/seal duct work. • Have the entire HVAC system routinely maintained—every six months is recommended. • Note that accordion style filters in the air handler and return air vents clog up easily, causing air flow obstructions that reduce system efficiency.

How your HVAC system works
The average homeowner has a working HVAC system that cools, heats and seems fine. But age and hard use are wearing it out. 12-14 years is a common life-span. The outside heat pump has a refrigerant, compressor, fan, condenser coil and various controls. In cooling mode, incoming gaseous Freon is compressed to liquid and the heat dissipated to outside air. In heating mode, outside air heat is absorbed into the Freon and flow is reversed.

When cooling, compressed Freon is pumped to the attic air handler to evaporate in an evaporator coil, absorbing heat from the indoor air passing over the coil. A fan motor and blower wheel force cooled air out to living areas.

Balanced air flow is important. A two-ton HVAC needs an air rate of 800 cubic feet/minute with vent returns/output ducts for this capacity, sealed against leakage, and unobstructed. The air handler also has heating equipment, an air filter, possibly an ultraviolet light, water drain system and other controls. Newer versions have variable speed motors.

The government mandated that new HVAC systems after January 2006 were to be 13-SEER rated. SEER is Seasonal Energy Efficiency Ratio: cooling produced (vs.) electricity used. For HVACs, at 10 SEER (since 1992), that’s up 30 percent. For older systems, going from 6 SEER to 13 means a 117 percent efficiency improvement.

By 2010, government is requiring beginning phase-out of Freon R22, because it contains chlorine. If leaked, chlorine destroys ozone in the stratosphere that shields life on earth from the sun’s rays. The replacement is R410A—no chlorine and a better heat transfer refrigerant. So, beginning in 2010, no new R22 systems will be built, although the Freon itself will be available until 2020. R410A is available now, but it can’t be used with old R22 systems. It won’t work.

Your options: • Continue old system operation until maybe 2020 (R22 replacement parts may not be available past 2010) • Replace the existing system with a complete new R410A system for an immediate increase in efficiency. With 16 or 18 SEER, you should see 40-50 percent cooling cost savings and payout in 8-10 years (not including future electricity cost increase) • If building a new home, install the highest SEER you can afford.

With variable speed motors, and programmable thermostats, one manufacturer claims you can get 33 percent electricity savings by selecting temperatures for different daily living periods. Cool can be 78 degrees 6-8 a.m.; 85 degrees 8 a.m.-6 p.m. (away—work, school); 78 degrees 6-10 p.m.; 82 degrees 10 p.m.-6 a.m. It’s the same idea for heating periods and can be different for weekends or vacations. Staying within one degree of setting, these thermostats start up, but motors run slower for a bit and may not need to reach high speed. They also start if humidity levels go up and have many other convenient features.

We exert little control over demand growth, how it’s met, and electric rates. However, you can do something to improve the overall situation by:

 Improving the performance of your existing HVAC system  Adjusting your lifestyle (temperature setting etc)  Checking your home for all electricity efficiency improvements  Changing to a new HVAC system with high SEER rating and new R410A Freon.

For excellent information on all electricity issues, visit Palmetto Electric’s website, www.palelec.com. Contact elected officials to support increases to electricity supplies with affordable, environmentally-responsible generation. Visit www.ourenergy.coop for easy dialogue with representatives to ask what they’re doing about this extremely important issue.

Selected information was provided by various utility websites and Superior Heating and Air, Inc.

About the Author:

Jim McCaffrey has engineering degrees from Ohio State University and enjoyed a
30-year career with Marathon Oil. He has been in the oil business for over 50 years.

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