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Spray Foam Went Well

rhl_ | Posted in General Questions on

Hi, 

I just wanted to thank all the authors and community members here. I’ve written here often, even had my house featured in an article:

https://www.greenbuildingadvisor.com/article/untangling-roof-insulation-goof

The issue in this article — was successfully addressed. We installed R-49 closed cell HFO foam under the roof sheathing, after checking it was dry.

The same contractor also installed above code quantities of HFO foam on our Rim Joists yesterday.

We are now going through a regime of aggressive air sealing and insulating!

The hope is to get to the point of net zero.. where our soon to be installed air to water heat pump will produce heat + ac + dhw, and reduce our load so much that our usage will be covered by our solar panels (maybe we will need to buy another small array).

Thanks GBA!

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Replies

  1. Expert Member
    BILL WICHERS | | #1

    I'm glad to hear your install went well! The one thing I'd recommend doing is check everything before you close stuff up to be sure that the spray foam hasn't seperated from the structure anywhere. If you have any little gaps, seal'em up with some canned foam. This isn't usually an issue, but every now and then it can pop up so it's worth checking.

    I wouldn't worry to much about net zero. I think sometimes that goal can actually discourage people. One example I usually use is solar and net metering: you don't need net metering for solar to make sense, solar can work fine on it's own in a peak-shave type of system. You still have a net benefit this way, but you can't go net zero this way. This is similar to the old saying "don't let the perfect be the enemy of the good".

    My advice regarding solar would be to size your system to run your load during the time the solar system is producing. Try to get on a "time of day" electric rate too, which will charge you more per kwh during the day (on weekdays), and less at night. This way your solar system is offsetting your load during the "expensive power" time, and you're saving money at night -- this maximizes your financial gain with a solar system without need of net metering.

    You'll end up with a more comfy house that is cheaper to win, and you're getting there by improving EFFICIENCY. This is a Good Thing! :-)

    Bill

  2. Jon_R | | #2

    > The hope is to get to the point of net zero

    Note that "net zero" is an arbitrary and usually inefficient line in the sand. It's doesn't mean zero emissions. It probably isn't the best thing to do for the environment with the "green" money you have to spend.

  3. rhl_ | | #3

    Well, the house will have zero direct emissions except in the case of an emergency for NG backup heat.

    All electricity will be produced by my panels.

    1. Jon_R | | #4

      I'll ignore "direct", since emissions are emissions no matter where they are shifted to.

      1 kWh supplied to the grid during sunny periods does not fully offset the emissions of 1 kWh taken from the grid during high use periods. And one needs to account for up-front emissions needed to get to "net zero kWh".

      > All electricity will be produced by my panels.

      You are running on batteries at midnight? Or are you borrowing from and loaning to the grid thinking that they cancel out on anything other than the irrelevant kWh metric?

      All this being said, a "net zero kWh" house does tend to have lower environmental impact. So I'm just encouraging you to look more closely at the details and achieve something more optimal.

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