Blue roofs can be used in combination with [[green roofs]] by employing a scaffold system to keep the vegetation rooting layer out of the ponded water. Blue roofs could also be employed in combination with a [[rainwater harvesting]] system which had daily usage demand. This could offset some part of the cistern capacity. | Blue roofs can be used in combination with [[green roofs]] by employing a scaffold system to keep the vegetation rooting layer out of the ponded water. Blue roofs could also be employed in combination with a [[rainwater harvesting]] system which had daily usage demand. This could offset some part of the cistern capacity. |