Lucas Hamilton is Manager, Building Science Applications for CertainTeed Corporation
Often, when I am conducting seminars on sustainable solutions for buildings, the question comes up regarding the benefits of a vegetative roofing system. One of the major benefits starting to take place provides a boost to a company or building owners’ bottom line – reduced water bills!
Some major municipalities such as Portland, Oregon are beginning to reward building owners with reduced water bills when systems are put in place in or on the building to reduce the storm water run-off. The reason for this is many municipalities have a co-mingled system where storm water and sewer discharge are carried through the storms drains to the treatment plant together. Very often, in a significant rain event, the capacity of the system is overwhelmed. As a result, the overflow of raw effluent runs into estuaries and the municipality can incur fines because the storm drains were overloaded.
What I have seen is that companies who take measures to control the rainwater run-off on their sites are starting to be rewarded for their efforts. One practice which is gaining in popularity is the utilization a vegetative or live roof and municipalities are rewarding companies for installing vegetative roofs by reducing water rates. That can be a significant savings for a large, multi-tenant building.
When you think about it, this is a very interesting angle that municipalities are taking to promote the use of green roofs. It is a win-win in that it controls utility costs for the building owner which offsets the cost of the installation of the vegetative roof. It is a positive for the community because it helps to maintain and prolong the life of the utility systems by not overloading them. It also can provide a nice environment for occupants if they have access to the roof.