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Where I am living, there are a lot of sheep, hence enough wool to go around for everybody. I saw a show at some point stating that sheep wool is one of the best natural insulates for homes.

Is this true? What kind of treatment does it need to go through from the natural state to the final product?

UPDATE:

For completeness reasons: a follow up question related to this one: best insulation

and also this one: newspaper insulation

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    Wool insulation is available in New Zealand, probably from several different manufacturers. I don't know much more though, so have made this a comment. – Highly Irregular Jun 2 '13 at 9:51
  • This is another one that falls into the category of "all-natural isn't necessarily very sustainable". There simply aren't enough sheep to produce enough wool to insulate our homes. Even if you happen to live in an area with a high ratio of sheep to humans, that's not scalable in any way, and if you limit your question to highly localized environments, doing almost anything can be considered "sustainable". – Nate Jun 2 '13 at 10:02
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    @Nate , thank you for your response...currently the farmers are burning the wool because nobody wants to do anything better with it. I think insulating a house is far better than that ;). – user503413 Jun 2 '13 at 13:54
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    @user503413, you're right, that burning it (which you didn't put in your question) is a waste. That said, the amount of wool needed to insulate a home is enormous. There's no possibility that such a scheme would ever scale to more than a tiny fraction of homes. As such, it's not really sustainable. Unfortunately, a great many on this site seem to confuse "all natural" with sustainable, which I think is a shame. If your question was about producing insulated jackets with excess wool, I would feel differently, as that solution does scale. – Nate Jun 25 '13 at 20:42
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Is it one of the best natural insulators? Well, that would depend on your definition of best. But it's certainly an effective insulator, and one with a commercial market.

It does have the advantage of being much more comfortable to work with than glass fibre.

I know of one installer who describes its comfort as a disadvantage too, because it's far too tempting to curl up in it for a little sleep while installing.

In Britain, it's sometimes sold as a blend of wool and recycled plastic. Others produce it as a 95% wool blend. From the pdf datasheet for that 95% blend, a 250mm layer has a U-value of 0.16 (= an R-value of 6.41)

Note that sheepswool is flammable, is biodegradable, is attractive to moths, and it does absorb water (without significantly impairing its thermal resistivity). So it will generally need treating to keep out mould and pests, and to give sufficient fire-resistance to be usable as a building material.

Its advantages (along with the comfort) also include the ability to lock in volatile organic compounds); additionally, most of the supply-chain is both self-reproducing and delicious.

And, as noted in the comments on the question, sheep are rarely farmed primarily for their wool any more, so the wool is a waste product: hence, reusing it for insulation (as long as the transport costs are not prohibitive) can improve the sustainability of sheep-farming.

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I use sheep wool to insulate my little cottage and it works great, it might seem you need a thicker layer though - as long as the beams can hold it, I will just add more wool on top. I use wool from my own sheep, so its free and the transportation cost is 50 meters :)

It is very important to discard bits of wool that have muck or sheep droppings on them.

It is very very important to treat the wool with Borax or other similar substance to make it unhabitable for moths. I didn't and I "enjoy" a massive number of moths flying out of my attic every spring.

The amount of mice living in the wool is very comparable to a similar setup using rock wool (experience from my last house).

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