A green roof, or 'living roof' really helps regulate the temperature of a house or building, keeping it cooler in the summer and warmer in the winter. You can even graze your goats on them! Indeed: goats can climb ladders, they are quite agile! generally only grass or wild plants that do not require deep soil are used or found on living roofs, and it is better to plan a building from the beginning to accomodate a green roof, retro-fitting is an expensive idea...but you can also have plant boxes on your roof, and even consider living walls! inside or out.