GoingTrueGreen's Blog Postings

Heat Wave

8/2/2013

Topic related GTG Video at our Youtube Channel

heat wave, heat, heatwave, WHILE formula, window airconditioners, AC units, EER, hot, how to save on AC units, how to buy an efficient AC unit, Bill Lauto, goingtruegreen, GTG

Are you having a Heat Wave?

If you are having a heat wave and need a new air conditioner, you will also need this formula... For those of you who saw our related video called Heat Wave on YouTube , this may prove to be an easier way to copy down the formula.

Using the W.H.I.L.E. Formula will help you when buying a new window or through the wall AC unit. This formula tells you the BTU size you will need to cool your room efficiently.

Sometimes salespeople at stores use a formula that only helps to sell inventory. So it is best for you to calculate your BTU size before you even leave your house.

The W. H. I. L. E. Formula divided by 60 equals the BTU size needed:

W = Width of your room
H = Height of your room
I = Insulation value in the walls
plug in the value of 10 for "I" when you have well insulated walls with R-13 or higher insulation value.
plug in the value of 18 for "I" when you have poorly insulated walls with R-11 or less.
L = Length of your room
E = Exposure
Take the longest wall in the room that is exposed to the outside and see which direction that wall faces:
plug in the value of 16 if that wall is facing North
plug in the value of 17 if that wall is facing East
plug in the value of 18 if that wall is facing South
plug in the value of 20 if that wall is facing West

Then multiply W x H x I x L x E divided by 60 to equal the BTU size you need

The WHILE formula DOES NOT calculate factors such as:
- Body heat, are you having a party? Body heat adds up.
- Window exposure, are they facing south or west or both? Do you have and use shades or curtains?
- Large openings into the room without doors.
- An Upstairs room, an uninsulated or poorly insulated Attic floor above, and/or is your roof Flat?
- Uninsulated Basement ceiling below.

Star rating, Yellow energy guide, EER, EnergyGuide, Room Air Conditioner, efficient AC units, how to buy an air conditioner

Yellow Energy Guide may look like this

Once you know your BTU size you can go shopping and LOOK for the Yellow Energy Guide Label on the floor models. You want to find a model in the BTU size you need that has the Highest EER number possible. The Energy Efficient Rating is very important and only the yellow guide label tells you if you are buying the best AC unit out there in your BTU size. Even if the AC unit has the Energy Star Label that DOES NOT necessarily mean you are buying the most energy efficient model made. You have to use the Yellow Energy Guide to know that.

Also don't worry about the most efficient model costing $75 or $125 dollars more, you will save that difference on the electric bill within the first full season of use. Please watch our related video for more detail info and extra facts. The Link is below. Thank you.

Bill Lauto, GTG
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4 Comments

BSB

8/2/2013 11:02:12 am

Excellent post - packed with information! I had never heard of the "WHILE" formula! This is going to come in handy now - as we continue with summer heat - and also in a few weeks when A/C units go on sale! Other considerations - whether the unit is adjacent to or even in a kitchen. Thanks so much for sharing your knowledge!

Bill, GTG link

8/3/2013 03:50:54 am

Hi BSB,

Great point about cooling the Kitchen. Talk about a battle between a hot oven cooking dinner and a AC unit trying to cool the room.

I will do a follow up showing a much more complex formula that does consider these additional heat sources. However, the formula isn't used much and I am not sure how to present it. The calculations are numerous and most people don't take the time to conduct the equations. The WHILE formula is used more because it is a faster way to a very good answer, not the best BTU answer, but very close. And yet, the WHILE formula is still not well known. Too many companies just want to sell their inventory of AC units and not train sales people with an energy, money and earth saving formula.

Thank you for your input and compliment, it is greatly appreciated.

Bill, GTG

Joe

8/31/2013 08:07:30 am

The Association of Home Appliance Manufacturers has a web based form that also helps calculate the size of BTU unit needed for a space for cooling.
http://www.cooloff.org/sub_cool.html
It factors in location, walls, space, doors, windows, people(!), appliances, lights, time of day in use, etc.
It does take some time and careful measure of the space before/as you fill in the form but, it does seem to be accurate as I have used it for two partial attic bedroom spaces on a home in a more northern climate and one in a more southern climate and it got the BTU pretty much spot on for two Energy Star window ACs I use in summer. The units do not cool continuously (undersized) nor do they over cool the space (oversized).

9/3/2013 03:52:21 am

Joe,
The BTU sizing formula you commented on does cover all details and as I previously replied to BSB's comment, I want to do a follow up showing this complex formula. However, surveys show this formula is too long and most people showed no interest in using it. My task now is to find an exciting and interesting way to present the formula so people will want to use it. Nevertheless, the WHILE formula almost always provides the best BTU size range, so no serious problems there. In the meantime, people can go to the website you listed for that version of the formula.
Thanks again for your feedback.
Bill, GTG