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How Energy-Efficient Is Your System?
The air conditioning and heating industry uses a measure known as “SEER” to rate the energy efficiency of air conditioners (“SEER” is an acronym for “Seasonal Energy Efficiency Rating”). In simple terms, the higher the SEER rating, the greater the amount of cooling that the system provides for each unit of electricity used.
Because of advances in technology and design, newer systems have a SEER rating as high as 15 or 16. In fact, Federal Government regulation now requires that new air conditioning units have a SEER of at least 10. By comparison, units that are 8 or more years old probably had a SEER rating of 10 or less when they were installed. Depending on the level of maintenance given the unit, that rating may now be much lower.
More information is available by visiting the sites listed below:
BTU and EER
Most air conditioners have their capacity rated in British thermal units (BTU). Generally speaking, a BTU is the amount of heat required to raise the temperature of one pound (0.45 kg) of water 1 degree Fahrenheit (0.56 degrees Celsius). Specifically, 1 BTU equals 1,055 joules. In heating and cooling terms, 1 “ton” equals 12,000 BTU.
A typical window air conditioner might be rated at 10,000 BTU. For comparison, a typical 2,000-square-foot (185.8 m2) house might have a 5-ton (60,000-BTU) air conditioning system, implying that you might need perhaps 30 BTU per square foot. (Keep in mind that these are rough estimates. To size an air conditioner for your specific needs, contact an HVAC contractor.)
The energy efficiency rating (EER) of an air conditioner is its BTU rating over its wattage. For example, if a 10,000-BTU air conditioner consumes 1,200 watts, its EER is 8.3 (10,000 BTU/1,200 watts). Obviously, you would like the EER to be as high as possible, but normally a higher EER is accompanied by a higher price.
Is the higher EER is worth it?
Let’s say that you have a choice between two 10,000-BTU units. One has an EER of 8.3 and consumes 1,200 watts, and the other has an EER of 10 and consumes 1,000 watts. Let’s also say that the price difference is $100. To understand what the payback period is on the more expensive unit, you need to know:
Approximately how many hours per year you will be operating the unit. How much a kilowatt-hour (kWh) costs in your area. Let’s say that you plan to use the air conditioner in the summer (four months a year) and it will be operating about six hours a day. Let’s also imagine that the cost in your area is $0.10/kWh. The difference in energy consumption between the two units is 200 watts, which means that every five hours the less expensive unit will consume 1 additional kWh (and therefore $0.10 more) than the more expensive unit.
Assuming that there are 30 days in a month, you find that during the summer you are operating the air conditioner:
4 mo. x 30 days/mo. x 6 hr/day = 720 hours
(720 hrs x 200 watts/hr) / (1000 watts/kW x $0.10/kWh) = $14.40
Since the more expensive unit costs $100 more, that means that it will take about seven years for the more expensive unit to break even.
See this page for a great explanation of seasonal energy efficiency rating (SEER).
What is Title 24?
The Energy Efficiency Standards for Residential and Nonresidential Buildings were established in 1978 in response to a legislative mandate to reduce California’s energy consumption. The standards are updated periodically to allow consideration and possible incorporation of new energy efficiency technologies and methods. The Commission in 2001 as mandated by Assembly Bill 970 to reduce California’s electricity demand adopted new standards. The new standards went into effect on June 1, 2001.
Though it is mandatory that new homes meet these standards, it has been our experience that homeowners are not realizing the full benefits they should due to:
- Installation not being to full compliance with Title 24.
- Improper system air balance.
- Improper refrigerant charging practices.
- Equipment not being maintained.
If you have any questions regarding compliance or feel your home may not be in compliance, please check here.
Interested in an evaluation of your system? Click here to schedule an appointment.
Some Technical Stuff
The cooling capacity of an air conditioner is based on the number of btu’s it absorbs per hour. One ton of cooling capacity = absorbing 12,000 btu’s of heat per hour.
BTU = British Thermal Unit: A unit measurement of heat. It takes 1 btu to increase the temperature of 1 lb. of water 1 degree Fahrenheit.
EER = Energy Efficiency Ratio:
EER = Btu’s / Watts
The higher the EER, the more efficient the machine, & the lower the cost of operation.
COP = Coefficient of Performance:
COP = EER x 0.293
The COP represents the cooling effect in btu’s of a refrigerant cycle, compared to the btu equivalent of the electrical energy put into the system during the cycle.
There are several factors that affect the number of kilowatt hours required to maintain a cool temperature in your home or office. One of the most important factors is the resistance of heat absorption. Therefore, a reduction in heat gain equals a lower cost of cooling. Improvements of attic insulation-ventilation, reducing air infiltration, window shading, & heat reflection will significantly reduce the heat load. High efficiency hvac systems & weatherization are energy friendly.