By Daniel Gregory, Sunset senior editor

The cavernous XtremeHomes factory at Oroville, an hour north of Sacramento, was full of activity last Monday as the media gathered for an update on mkLotus, the latest green prefab. We saw the fully installed folding glass panels, which are called Nanawalls, "Disapparate"—to use a J. K. Rowling term—three sides of the living-dining room. They silently glide away to unite inside and outside: this is how to live large in a small space. Bedroom and living room walls are almost completely taped. Next will come the cabinets, flooring, siding, plumbing fixtures, appliances, and paint. And soon the house will roll down the highway to West Coast Green. It was exciting to see the progress and though the drive back to SF took a while, a timely root beer float kept the occupants of my hybrid happy. How green, I mean, cool, is that?!