Replies

1. GBA Editor
   Martin Holladay | Nov 10, 2015 07:29pm | #1

   Tim,
   Here are links to two articles on the topic:

   Deep Energy Makeover: One Step At A Time

   Brand New Appearance and Performance for An Older Duplex

   .

   
2. 
   charlie_sullivan | Nov 11, 2015 01:02pm | #2

   A disadvantage of spray foam and XPS is that they are both made with blowing agents with very high global warming potential (> 1000X worse than CO2). So EPS, polyiso, and mineral wool are preferable from an environmental impact point of view.

3. 
   TimL_in_ND | Nov 11, 2015 04:01pm | #3

   Thanks Charlie,
   I've been trying to make a comparison of using spray foam to the equivalent burning of gasoline in a car based on: one gallon of gas will emit 18 lbs of CO2.

   For my project:
   2200 sq ft 3" thick in cubic ft is: 2200*0.25 = 550 ft^3.
   Assuming 2lbs of foam per cubic ft: 1100 lbs of foam.

   How much CO2 equivalent is released per board ft of spray foam? Couldn't find a conversion in my limited searching. Certainly more complicated that the above but is useful for comparing the impact of spray foam to something tangible - filling the tank at the gas station.

   Thanks
   Tim

4. 
   charlie_sullivan | Nov 11, 2015 04:49pm | #4

   That's a good question. Rather than calculating it myself I looked around and found this article,

   https://www.chemours.com/Formacel/en_US/assets/downloads/201109_Life_Cycle_Analysis_Spray_Foam.pdf

   Fig. 3 shows 22 lb CO2 equivalent per square foot per R-13, or in other words, 1.7 lbs per (sq foot R value). I'm not sure what R-value you had planned, but for R-16 and 2200 square feet, that's 60,000 lbs. of CO2, or 300 gallons of gas, or 120,000 miles of driving at 40 mpg.

   At that rate, you could buy EPS one sheet at a time, and drive 800 miles round trip to get each sheet, and still come out ahead! (On global warming emissions--not on your time or your sanity.)

   The article I used is from DuPont. They are unlikely to exaggerate the impact of the blowing agents they sell, so it's likely that result is conservative.

5. 
   TimL_in_ND | Nov 11, 2015 05:32pm | #5

   Thanks Charlie,
   One math correction...
   60,000 lbs of CO2 / 18 lbs per gallon gas >3000 gallons of gas! Yikes.

   For propane, its 12.7 lbs CO2 per gallon. 60000/12.7= 4700 gallons propane.

   If current use is 1000 gallons per season and is cut in half by adding insulation (and new windows that are planned), then the CO2 emitted by insulating would be made up by less propane use in ~10 years.

   Useful discussion. I don't feel quite as guilty going with the spray foam - will be less CO2 overall in 10 to 15 years.

   Tim

6. 
   charlie_sullivan | Nov 11, 2015 08:16pm | #6

   But why wait 10-15 years to get the benefit when you could have it in the first year with EPS...or with open cell spray foam.