The traditional way to demolish a building is to bring in the 'Cat' to smash and crash its way through the structure ending up with a huge mixed debris pile that is transferred to dumpsters and trucked to the landfill.
Many times hazardous waste gets thrown into the mix and there is a real danger of ground and water contamination at the landfill.
The 'best practices' and sustainable alternative to demolition is "Deconstruction". The goal of deconstruction is to take apart the structure in such a way that most of the original building materials can be reused or recycled in some way. The landfill is the last resort and is only used for a very small percentage of building materials which could not be reused or recycled. In the first stage of the deconstruction, reusable and recyclable materials are stripped from the building and sold, donated, reused or reintegrated into the project. In the second stage the envelope is is deconstructed and sorted into piles (i.e. concrete, wood, metal and glass).