Using reclaimed or recycled soft or hardwoods has a low impact on the environment, since you're using a material that was already harvested long ago. This means no new trees need to be cut to install your floor. Reclaimed woods can typically be salvaged from old properties; you can even get great deals if you shop around.
Bamboo looks and feels a lot like hardwood, but since bamboo is a grass and not a tree, it's easily replenished. The bamboo used in flooring is harvested from managed plantations and grows back in about four years. (More on bamboo flooring, including a picture)
Cork is manufactured from the bark of living trees (without hurting the tree itself), so it's an ideal sustainable material. In fact, the harvesting of cork bark actually stimulates the growth of the tree. (More on cork flooring)
Recycled Glass Floors
Today, old beer and wine bottles are being recycled and transformed into glass floor tiles. The cracking and bubbling that is a result of the recycling process adds visual interest to the floor.
Linoleum is made from linseed oil, wood flour, pine resin, and ground limestone, which is spread on top of a jute backing. Linoleum doesn't release toxic fumes, and it is biodegradable.
Made from sisal, sea grass, jute, and coir, natural-fiber flooring enables Third World countries to benefit from their local sustainable resources. The products are also biodegradable.
Recycled Rubber Flooring
You can get rubber carpet padding and rubber flooring (which usually comes in interlocking tiles or mats) that is made from shredded tires. Every 100 square feet of flooring keeps 7.5 tires from going into land fills. Recycled rubber is popular for home gym areas, or any place a bit of padding underfoot is desirable.
Source: The Flooring Handbook: The Complete Guide to Choosing and Installing Floors
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