Are the materials or components renewable? Does its harvesting or manufacturing contribute to the degradation of the environment? Are there any harmful byproducts or dangers to human or animal health?
Positive contribution to indoor air quality
Does the material or product emit VOCs or offgas in the application or through its lifespan?
Does it last and stand up to more than just normal wear and tear? Does it outlast other similar products? A building product is only environmentally sound if it lasts.
Will it contribute to a long-lasting pleasure in your home? It is only environmentally sound if you're not tempted to rip it out and replace it with something else.