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(This is a draft of a fact sheet with the math and savings of using the AIR system. Feel free to write bobsyouruncle@nonviolentworm.org with suggestions of how to improve this information. Coming soon the children’s book version of the AIR system tentative called “The Hare, Hair and Air”.

Air Insulation Resource (AIR) System: The Facts


Ask any bird with feathers, or a goat with hair or any Eskimo with layers of clothing what the principal source of heat in the cold for their bodies is and they will answer Air, not feathers, hair or clothes. It is the air pockets caught in the feathers, the hair, between layers of clothes that are the principle source of heat. This principle of using air to keep in heat and cold out is the same in the Air Insulation Resource System. (AIR) However, we thinking human beings need cold hard science to back this principle up. For our five- pane window inserts in the sunroom we used various methods to measure the cost savings on the inserts. John Kruschke, the inventor and I once took all the window inserts out on a cold night, turned off the heater and then measured how many degrees the sunroom dropped in an hour. We then heated up the room, put back the inserts, turn off the heater and measured again. Another method we used is measuring each night the temperature inside the sunroom, the temperature outside, the temperature inside the house attached to the sunroom and the number of kilowatt hours (KWHRs) used by the heater. Note that a 500-watt heater running for 2 hours is the same as a 1000-watt heater running for one hour – they both use a “kilowatt hour.” You can find these numbers at the bottom of a number of Diary of the Worm (see below) postings in the winter months.

However, the most universal and scientific measurement of heat gain and lost of the AIR system came from my friend, and John’s father, David Kruschke in Madison, Wisconsin. Using information from the weather bureau and the way of measurement of ‘degree days’ from the energy companies he developed the following chart using the usual 65 degrees as the inside temperature at which you normally would not need a source of heat.

 SepOctNovDecJanFebMarAprMayTotal 
Inside Temps656565656565656565  
Outside Temps625038241923334455  
Differences31527414642322110  
Differences greater than zero31527414642322110  
=deg days/month904658101271142611879926303107181 
            

(1)

By using the thickness of glazing (clear plastic or glass) and the measurement of trapped air in each layer he was able to measure the R factor with or without the inserts. R is the total number of hours required for a BTU (2) to escape per hour when there is a one degree Fahrenheit difference between inside and outside temperature. The R factor with just one layer of glass was .99. However, with the inserts the R factor value increased to 4.43. This means that it would take one hour (.99) for a BTU to conduct to the outside with one layer of glass while it would take 4.43 hours for that same BTU to leak out the area with the inserts. By applying 1/R, we get heat flow rates of 1.01 BTUs (1 divided by .99) per hour per degree difference, inside versus outside, and .23 BTUs per hour (1/4.43) per degree difference, inside versus outside. The net difference here is .78 BTUs per hour per square foot per degree difference between the inside and the outside temps. We then use this information with 24 hours per day and degree-days for the season for each scenario. This will leave us with two BTU values per heating season. And since a 1000-watt space heater puts out about 3400 BTUs per hour, one can convert each BTU value to numbers of hours needed to run one on these heaters for each scenario. And the cost for each scenario would be based on the current cost of a kilowatt-hour as sold by the Electric Company. The savings, then is about 18.72 BTUs per square foot per degree day and this number times 7181 degree days gives us 134,428 BTU or about 39 kwhrs per square foot. Using about 13 cents per kwhr, we get a saving of about $5.00 per square foot or a little over $900 for all 184 square feet of inserts.

David was able to do this for September through May using the inserts.
This $900 plus savings is based on the fact of keeping my sunroom at 65 degrees for 9 months of Sept. – May. My actual savings was less since I allowed the temperature to go below 65 degrees for many of these months. Also since three sides of this three season sunroom are just glass doors, the heat required to keep it at 65 degrees is greater than a regular room of same size in a house. A more accurate savings calculation would have to consider this.

However, 65 degrees is a good number to use in measurement since it allows us to measure the savings of the eight small storm windows that I covered with a layer of clear plastic on each side. Using the same formula each window with the two additional layers of ‘glazing’ saved me $ 2.10 per square foot for the season. That might not seem like much but for about 5 sq. feet per window this would be a savings $10.50 per small window. For eight small windows this would mean a savings of $84 per season. Now you can imagine the savings if you did larger windows with this AIR system. One could save two to five hundred dollars per house on heating cost with about $20 of supplies, a hair dryer and a little simple

Simply put each five-pane window insert can save $80 over a season in energy cost to maintain a 65-degree temperature. Each small window with clear plastic on two sides of storm saved $10.50 in keeping a 65 degree temperature over 9 months.

(1)As a reminder, 6500-degree days can take different forms while still requiring the same amount of fuel. If one went through a period of 100 days where the average daily temperature was 0 degrees F, the difference from 65 degrees (the temperature where no fuel is really needed) would be 65 and 65 times 100 (days) would be 6500-degree days. On the other hand, if one went through a period of 200 days where the average daily temperature was 32 degrees F, the difference from 65 here would be 33 and 33 times would be 6600, very close to 6500 degree days. Again, the fuel needed for both of these scenarios would be almost the same.

(2)And while “BTU” stands for British Thermal Unit, there is a better definition and it is the amount of heat needed to raise one pound (16 ounces) of water one degree F.

Use the charts below to figure out how much you can save with the Air Insulation Resource system. Glazing means glass or plastic barrier.

Add pockets of AIR and save heating cost chart.
Go from Cost/heating season/sq. ft. of $6.24 to Cost/heating season/sq. ft. of $1.50 by adding pockets of AIr

Layers#sUnits
Outside air0.25hrs/BTU/deg diff
Glazing0.06hrs/BTU/deg diff
Inside air0.68hrs/BTU/deg diff
Total R0.99hrs/BTU/deg diff
U1.01BTU/hr/deg diff
times2424.24BTUs/deg day
times 7324177552BTUs/heating season
divided by 341352.02KWHRs/heating season
times .12$6.24Cost/heating season/sq. ft.
   
   
Layers#sUnits
Outside air0.25hrs/BTU/deg diff
Glazing0.06hrs/BTU/deg diff
Trapped air, 2″0.50hrs/BTU/deg diff
Glazing0.06hrs/BTU/deg diff
Inside air0.68hrs/BTU/deg diff
Total R1.55hrs/BTU/deg diff
U0.65BTU/hr/deg diff
times2415.48BTUs/deg day
times 7324113404BTUs/heating season
divided by 341333.23KWHRs/heating season
times .12$3.99Cost/heating season/sq. ft.
   
   
Layers#sUnits
Outside air0.25hrs/BTU/deg diff
Glazing0.06hrs/BTU/deg diff
Trapped air, 2″0.50hrs/BTU/deg diff
Glazing0.06hrs/BTU/deg diff
Trapped air, 1/2″0.80hrs/BTU/deg diff
Glazing0.06hrs/BTU/deg diff
Inside air0.68hrs/BTU/deg diff
Total R2.41hrs/BTU/deg diff
U0.41BTU/hr/deg diff
times249.96BTUs/deg day
times 732472936BTUs/heating season
divided by 341321.37KWHRs/heating season
times .12$2.56Cost/heating season/sq. ft.
   
   
Layers#sUnits
Outside air0.25hrs/BTU/deg diff
Glazing0.06hrs/BTU/deg diff
Trapped air, 2″0.50hrs/BTU/deg diff
Glazing0.06hrs/BTU/deg diff
Trapped air, 1/2″0.80hrs/BTU/deg diff
Glazing0.06hrs/BTU/deg diff
Trapped air, 1/2″0.80hrs/BTU/deg diff
Glazing0.06hrs/BTU/deg diff
Inside air0.68hrs/BTU/deg diff
Total R3.27hrs/BTU/deg diff
U0.31BTU/hr/deg diff
times247.34BTUs/deg day
times 732453754BTUs/heating season
divided by 341315.75KWHRs/heating season
times .12$1.89Cost/heating season/sq. ft.
   
   
Layers#sUnits
Outside air0.25hrs/BTU/deg diff
Glazing0.06hrs/BTU/deg diff
Trapped air, 2″0.50hrs/BTU/deg diff
Glazing0.06hrs/BTU/deg diff
Trapped air, 1/2″0.80hrs/BTU/deg diff
Glazing0.06hrs/BTU/deg diff
Trapped air, 1/2″0.80hrs/BTU/deg diff
Glazing0.06hrs/BTU/deg diff
Trapped air, 1/2″0.80hrs/BTU/deg diff
Glazing0.06hrs/BTU/deg diff
Inside air0.68hrs/BTU/deg diff
Total R4.13hrs/BTU/deg diff
U0.24BTU/hr/deg diff
times245.81BTUs/deg day
times 732442561BTUs/heating season
divided by 341312.47KWHRs/heating season
times .12$1.50Cost/heating season/sq. ft.

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