Blowing past the speed limit on the highway lowers your car's fuel efficiency. So...

Cherry, maple, oak, elm and other deciduous trees fall into this category of wood. They are slower-growing trees than softwood conifers such as pine, and are sources of durable, valuable, and undeniably good-looking timber for flooring and furniture. The market for hardwoods has led to damaging forestry practices the world over, but some logging companies harvest more gently; when shopping for hardwood products, look for those certified by Forest Stewardship Council (FSC)-a sign that the wood came from a sustainable, well managed forest. Salvaged hardwood (rescued from buildings scheduled for demolition, for example) is another tree-friendly choice.

Mold isn't just a patch of blue to indicate your bread's gone bad. There are molds that grow on...