This is a very complex question. And it depends on what elements are being measured. Often people interchange the words “cement” and “concrete”. But Portland cement is only one of the ingredients that make up concrete. Because cement gets quite a bad rap – because of its carbon dioxide emissions – it is often thought that concrete is not a green building material. But the end product of the manufacture of concrete presents a very green building alternative. Concrete is sustainable and because it is long-lasting, energy efficient and versatile, recyclable, it can help builders achieve LEED certification. Concrete is the foundation of modern life. Combined with steel, it is what holds up buildings, keeps dams from splitting open, and our electrical grid intact. But like everything, concrete needs to be used correctly and in harmony with nature.