WHAT YOU NEED TO KNOW ABOUT COOLING YOUR HOME
The central air unit in the photo above has a SEER (Seasonal Energy Efficiency Rating) of 12 to keep the electric costs low. The HIGHER the SEER, the lower the electric cost. Look for units today with at least a SEER of 14 for best results with costs and pay back times.
Also listen to a NYC radio report below:
Before you buy an Air Conditioner for your window or through-the-wall you must calculate how many BTUs (what size air conditioner) you need.
Below are the formulas for sizing AC units and getting the proper amount of BTUs.
Most formulas we have all heard and still hear from many Sales people are NOT correct and will cost far more on the electric bill. For one example of an incorrect formula, see the next paragraph:
Length of room multiply Width of room multiply by 100 equals BTU size.
10 feet X 10 feet = 100; then X 100 = 10,000 BTUs. This is WRONG.
A ten by ten room would most likely need only a 5,000 BTU air conditioner. Worst case - still only 6,000 BTUs.
The above formula only sells inventory and can double your electric bill, PLUS make the room CLAMY! This is because the AC unit is double the size needed, thus the compressor will cycle on and off, on and off, on and off, leaving the room sticky and clammy. Basically the AC unit can never get rid of the Humidity in the room because it is oversized.
NOTE: Since sizes of air conditioners vary in BTU's from one manufacturer to another, always choose the one with the highest E.E.R.* and is closest to the BTU size you need. DO NOT buy an AC unit just because it has the Energy Star Label on it. This label shows that it at least meets the minimum requirements to have an Energy Star Label, BUT the Energy Star Label DOES NOT automatically mean you are buying the MOST Energy Efficient Model made! You MUST read the YELLOW Energy Guide charts on the AC unit to determine that. If the models in the store you are shopping in are not the most efficient, then leave and go to other store to see different brands. Find out which Manufacturer makes the most efficient model in the BTU size you need. (Or as close as possible to the BTU size you need). And buy that most efficient model, even if the unit costs more, you will save the price difference off the electric bill usually within one summer.
* (EER means Energy Efficiency Rating)
Part Two has another radio spot and a game to play for testing your AC knowledge! Click Here
A much better formula to use is called:
The W.H.I.L.E. formula.
Proper sizing of a ROOM air conditioner is dependent upon the cooling load, or the amount of BTU/HR the air conditioner must have to cool the room in order to maintain the desired temperature. (BTU/HR means British Thermal Units Per Hour)
The cooling load can be determined by using the W.H.I.L.E. formula then Divided by 60 as shown below:
W = Width of room
H = Height of room
I = Insulation value in the walls
(Use the # 10 for WELL INSULATED or 18 for POORLY INSULATED rooms. An insulation value of R-11 or lower will be poorly insulated. Learn more with our Insulation Blogs.)
L = Length of room
E = Exposure. Which direction the longest outside wall faces.
(North use #16; East use #17; South use #18; West use #20)
Multiply: W x H x I x L x E
Divide by 60 to equal (=) BTUs needed.
Bill Lauto, at GoingTrueGreen.com
International Sustainability and Energy Consultant
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