I like that term "freezing point." Meshes nicely with the loss of percolation in adaptive pathways, which we are going to experience as available energy decreases. All of the industrial ecology made possible by cheap energy will "freeze" and collapse, just as we are collapsing the older biological ecologies. It is a true phase transition, just like the process of freezing or thawing.
This piece considers that industrialisation could only happen with cheap fuels, and by looking at the countries of the world, tries to figure out just how cheap fuel has to be before lots of people start using it – before a country can industrialise with fossil fuels. The flipside to this is seeing how expensive fuel must be before it deindustrialises. This then gives us a clue to if and when will industrial society will end.
By an “industrial society” I mean one in which machines are powered not by human or animal motion and are a part of everyday life, and we design our homes and cities with machines in mind. A non-industrial society may have some machines, but it's not designed around machines; a Kalahari Bushman can happily use a radio, but he does not live in an “industrial society”, whereas his cousin who moves to Johannesburg and takes the bus to work does, even if she has no radio.
Going from a mostly-manual or animal economy to an industrial one, you can think of it as like the melting of ice into water at 0°C. When there's enough heat (cheap energy) it melts (becomes industrial). But does the reverse apply? If you cool water down to 0°C, it'll freeze. So if the cheap fuel becomes expensive, will we lose all that industry? Does industrial society have a freezing point, a point at which the heat (energy) has been drawn out of it, and so it changes from liquid (industrial) to solid (non-industrial)?
http://anz.theoildrum.com/node/3228