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View Diary: "Winter Deep Freeze Will Cause Breakdown of German Electric Grid" (245 comments)

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  •  Not correct. (10+ / 0-)

    Not that it's a bad idea, but in the vast majority of situations simple payback for insulation is much more than a year or two.

    The only way you get a rapid payback is if you use a very expensive heating fuel (e.g.: fuel oil, electricity) and increase your insulation from next-to-nothing to very good, for example: from R-5 to R-38.

    Most of us start out somewhere in the middle. We have a gas furnace and maybe our roof insulation is R-19 and we increase it to R-38. In typical cases like that simple payback takes 5 to 8 years.

    Outside of a dog, a book is man's best friend. Inside of a dog, it's too dark to read. - Groucho Marx

    by Joe Bob on Wed Feb 08, 2012 at 06:07:25 PM PST

    [ Parent ]

    •  The payback is based on cost of subsidized energy (0+ / 0-)

      which is very low. If you double your house insulation you cut your energy cost in half. If you quadruple it, you reduce it by 4 times. Instead of subsidizing fossil fuels we should be subsidizing insulation.
      Also a heat pump lasts 15 years but house insulation lasts the life of the house--+50 years. It makes no sense to go to a heat pump if the payback is 20 years.
      OTOH, solar PV lasts about 25-30 years.

      •  I'm all for insulating our houses. I did that and (0+ / 0-)

        my bill dropped...15%. Worth it. But no doubling (went from ZERO insulation to R-13).

        You don't double your insulation and halve your bill; quadruple it and reduce it by another 25%. Insulation doesn't work like that.

        This is why those promises should be banned from advertising. Insulation on your home is good because it WILL lower your heating (and AC) bills. But by how much depends other factors and how much you are spending to begin with; if you live in very cold climates, etc.


        Dr. Isaac Asimov: "The most exciting phrase to hear in science, the one that heralds new discoveries, is not 'Eureka!' but 'That's funny ...'"

        by davidwalters on Thu Feb 09, 2012 at 10:15:36 AM PST

        [ Parent ]

        •  You have to insulate the WHOLE house and leakproof (0+ / 0-)

          it. If you went from an uninsulated R-6 and put in R-13 fiberglass batts(which are only good for R-9 due to thermal bridging) your wall heat loss should go down by 60%.
          Insulation is a LOT trickier than just blowing some insulation in the attic and you have to air seal very carefully. That includes doubling the window R values, insulating the basement walls, floor.

          But if you really double all your insulation R values by the laws of physics you should cut your heating/SC bills by half.

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