Don’t know about which sources are being used, but I think an acre of timber is pretty extreme. Modern construction uses materials in a pretty efficient manner. OSB (orientated Strand Board) is a good example.
That said, I’ve seen ‘cobb’ and straw bale houses that are really solid and well insulated. I’ve been in a couple of structures at least as solid as my pre-WW2 lathe and plaster home which is framed with true 2 inch by 4 inch redwood boards.
Wood has its primary advantage being inexpensive, light in weight to transport and easily modified at the site.
I gather she heats it with a C size battery ~ (actually, not much more than that ~ you have to use triple glazed windows of course).
Just in case it gets really cold she also has an in ground heat exchanger hooked up to an ordinary forced air system..