check out the green building talk forums (external website), lots of folk around there who know more and can help.

We just built an ICF home and love it. Super quiet, super strong, and energy efficient. We are in Canada though.

what is ICF?

Go to greenbuildingtalk.com and post on the ICF forum.

An ICF house, if built correctly, will be very quiet and usually fairly energy efficient. Best, it will also last much longer than typical wood framed houses - like hundreds of years vs 50-70. Overall they are very nice houses to live in.

On the energy efficiency side it really depends on how much foam there is on the interior and exterior, how the penetrations for windows, doors and other stuff is handled, as well as attachments like floor joists and roofing trusses. An ICF can also be done as a PERSIST which is probably the ultimate.

For windows & doors you'd probably want to stick to Optiwin, Zola or similar for the best energy efficiency. For double hung then Loewin is probably your best option.

Make sure either the sub doing the ICF work or the architect/designer have experience with ICF's and are involved in the project from the beginning of design. There are a lot of little things that are different about ICF construction that are good to be aware of up front.

How do they hold up in earthquakes?

Like any concrete wall of the same specs. Our walls are 8" of concrete with re-bar on 16" centers both horizontal and vertical. Way overkill in our area. The ICF forms themselves aren't structural.

Insulated Concrete Form. Architect and builder must have experience with this and must be strongly recommending or else I would bail.