[Ar.Axel Ritter]

The materials that can be recycled or are manufactured from waste are sustainable building materials.

The local dump is a great place to look for such stuff because it is often perceived as valueless. Our local dump actually has an area set aside for potentially reusable items, and they encourage people to sort through it. We found our kitchen sink there, in perfectly good condition, except for a little chip in the corner that I covered with tile. The virtue of recycling used building materials lies in diminishing the need for industry to recreate it. All of the energy that is spent in manufacturing and transporting something can be saved. The raw materials that would be drawn from the earth can be saved. The need to cover the item in the local landfill can be saved.

An example of how a building can transform mechanical energy into electrical energy is the project Hybrid Muscle by the French architects R&Sie : a 3t counterweight placed In a building was raised by a white buffalo and provided enough electricity from a dynamo-electric generator for the lighting, a laptop and a telephone system.

There are also a few instances where the energy comes from humans, for example by converting their movements into electrical energy; this could be during sport or whilst walking. A current interpretation along the lines of this theme is provided by the architect Mitchell Joachim with
his idea of a floating fitness studio. The sporting muscle power of the people using the gym is converted by suitable means into electrical energy and used to drive the RiverGym NY, which - sheltered against the weather by a transparent protective cupola - is able to change its surroundings again and again.