What is EER

In technical terms, EER is the steady-state rate of heat energy removal (i.e. cooling capacity) by the product measured in Btuh divided by the steady-state rate of energy input to the product measured in watts. This ratio is expressed in Btuh/watt.

SEER rating more accurately reflects overall system efficiency on a seasonal basis and EER reflects the system's energy efficiency at peak day operations.

An expansion on the prior posting.

EER is the Energy Efficiency Ratio- cooling out per kW in. It is based on system performance with 80F entering air and 95F condensing air temperature (assuming air-cooled condenser).

SEER is Seasonal Energy Efficiency Ratio- same ratios but based on performance with the same 80F entering air but with an 82F condensing temperature- closer to the AVERAGE annual outdoor cooling temperature conditions. The actual "cooling" season for most homes is between 68F and 95F outdoor temperatures. The 82F is essentially the mid-point or average outdoor (condenser inlet) temperature. Hence the "Seasonal" designation.

SEER ratings produce the best way to compare various systems because they are based on an overall operation, not just a single point. A system with a SEER that is 10% higher than another system will likely operate at 10% lower cost. Generally, units with 2-speed compressors have higher SEERs than those with single speed compressors, but the 2-speed units often have EERs that are lower than single-speed units (that have been "tuned" for peak performance at the peak load conditions.

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.

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 and 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're operating the air conditioner:

4 mo. x 30 days/mo. x 6 hr/day = 720 hours

[(720 hrs x 200 watts) / (1000 watts/kW)] x $0.10/kWh = $14.40

The more expensive unit costs $100 more, which means that it will take about seven years for the more expensive unit to break even.

thanks for your detailed explanation but you have not mentioned anything about SEER.i have come across one example which i am reproducing below.

consider 5000btu/hr air conditioner unit with SEER of 10 btu/w.hr operating for a total of 1000 hrs during annual cooling season(e.g 8 hours per day for 125 days .

5000btu/h*8h/day*125days /year=5000,000btu/year

with a seer of 10, the annual electrical energy usage would be about.

5000,000btu/year/10btu/w.h=500,000w.h/year

will you please explain how Seer comes out to be 10

Mr.Salahuddin Zia - After having gone through all your threads it seems that you are out there on Energy Audits (particularly electricity) and it seems that you have little experience in this"Energyv Audit" field and practically none in the boiler/steam field. You are out requesting electricial data / reports from members on hatchery/gum/etc., and very recently you started a couple of inter-related energy efficiency threads. Basically you are getting your homework done from us.

Who are you? What is the name of your Company?

I will appreciate you being really honest in your reply before anyone of us proceed further.

If you do not wish to disclose the name of your Company then it will not be difficult to find out too.

thanks for your reply.if you recal i had mentioned that i am learner to this audit energy subject.i am suppose to do the electrical audit and that too on motors and lighting system installed in the factory.nothing to do with boilers/steam for my knowledge sake i am asking these questions .in case you are not comfortable to answer my question its fine.you have all the right to find out our company name as we are not stealing knowledge from any one we are trying to increase our knowledge.by asking few question will not complete the electrical audit report but obviously add good points to the report.moreover dont think i have asked someone to do homework for me .yes i do have the right to ask questions and i am sure you dont have right to stop me from doing that

i had mentioned that i am learner to this audit energy subject.

Thats an honest answer and i like it. i am sorry you took me the other way.

by asking few question will not complete the electrical audit report but obviously add good points to the report.

This I will agree with you.Please do not take me wrong for I have no right to stop anyone from seeking knowledge because i too do the same.

thanks for your reply i am really elevated with your sincere reply and guidance before i move forward i must thank all of you for answering my questions ,i take the liberty to thank you personally for being there to guide us.yes i do understand that few questions do not complete the report but it does add Cream and sugar to it when good gentlemen like you and others around the world are their to guide us.thank you once again and good luck and hope you will try your best to answer my simple questions also.

I was impatiently waiting for this reply and happy to see that you are really and honest guy and good to heart. I'd simply love to help you out whenever.

Thank you for your understanding

It is normally reffered as:

Seasonal Energy Efficiency Ratio (SEER)

An excerpt from the Wiki - for who ever was claiming a SEER of 40 or some such number a few days back.

Maximum SEER Ratings

Today there are residential AC units available with SEER ratings up to 23.^[3] There are a variety of technologies that will allow SEER and EER ratings to increase further in the near future.^[4] Some of these technologies include rotary compressors, inverters, DC brushless motors, variable-speed drives and integrated systems.^[4]