Deconstruction: Instead of dramatic building demolition a la Fight Club, green builders carefully disassemble the building piece by piece. Safety precautions are strict, as a lot of buildings have asbestos and other dangerous chemicals floating around. The sites are also dangerous. Think about what is in an abandoned building: burst pipes, raw sewage, rodents and insects. Sometimes squatters come in and make the building home, leaving behind needles and condoms.
Despite these dire conditions, there is almost always salvageable material to be found. Reconstructors sell as much of the old furniture and equipment as they can. Sometimes the frame of the building can be sold as a whole to make a new building. Otherwise, a steel frame can be recycled or a wood frame can be sold to builders and do-it-yourselfers at about 40% of what it would be at Home Depot.
Reconstruction: As mentioned above, some builders use an old frame rather than create a new one. In Ottawa, the local MEC(Mountain Equipment Co-op) is built around the frame of an old grocery store. The proponents of green buildings use design for disassembly so when the building is at the end of its life, it can be easily pulled down and its parts reused.
Why hasn't this trend taken off, and why is it more popular in North America than in countries with less space? There are many people against green buildings. Constructing them requires a whole new set of skills, and the traditional trades are fighting it. One green architect was asked not to mention some of his deconstruction techniques at a trade show. The organizer said it would cause too much controversy. Since around 25% of our landfills are stuffed with construction waste, it seems like this is the only reasonable way to ensure sustainable building. Hopefully the construction industry will work and grow with the trend instead of fighting to stop it.