To answer to this question, you need to decide what is more important to you. Carpet and Tile can both be green, if you make the right decisions.
Tile is a great alternative to natural stone. Most tile is made from locally mined clay, and glazed locally. If you find a company that produces tile locally, it can be a very green choice. Also consider tile made from recycled glass, which can be both beautiful and durable.
Try to avoid natural stone unless you know where it came from. Italian Marble sounds elegant, until you realize how much fuel it takes to float a big rock on a boat from Italy to the U.S. Then, it just seems silly. Even locally mined stone can cause environmental impact. Mines can cause wildlife displacement, disruption of water tables and river flows, and cause other unintended environmental problems. Do your homework if you want to go with natural stone. Let your concience guide you on this one.
Carpet is soft and cushy. It feels warmer and is more comfortable to sit on and walk on. It also traps dust mites, pet hair, dirt, and mold. There is also concern that carpet can trap pesticides and herbicides that travel into your home on your shoes, causing a danger to children and pets. These dangers can be avoided with regular cleanings, but even cleanings can cause their own problems if not done correctly.
If you decide you need carpet, check out PET carpet. PET (polyethylene terephthalate) carpet is made entirely from recycled 2-litre soda bottles. The carpet feels soft and cushy, but is stain-resistant, static-proof, and, because it is entirely plastic, doesn’t harbor the mites and mold that cotton or wool carpet can. It also causes less of an impact to produce, and the dyes used to color it give off fewer VOC (volitile organic compounds) than those used to dy textile carpets.
In the end, it’s a personal decision. What is important to you? Is it imperative that you have granite or marble? Maybe a glass or ceramic tile is better. Do you need carpet? Or can you do a solid floor with a couple of throw rugs? Make the choice by balancing research and personal taste, and you will make the decision best suited for you.
As for me, I’m a hard surface floor with throw rugs kind of guy, but that’s just me.