Staff Photo by Robin Rudd
Hamilton County Health Department.The County Commission will be asked Wednesday to approve the county Health Department’s plan to install a green roof to replace a section of worn-out roofing at its Third Street center. Approval should be an easy call. For a number of cost-efficient environmental reasons, roofs covered by vegetation are bound to become a national norm in the future, especially in cities. Hamilton County government should already be headed in that direction.
The lifetime value of green roofs reflects a range of benefits that easily offsets the marginal difference in up-front costs. Among the chief factors are longer life than traditionally finished flat roofs, energy efficiency, reductions in municipal costs for managing urban stormwater runoff and reductions in the “heat island” problem in cities.
The latter two are especially significant. And their advantages accrue to local governments and taxpayers in reductions of their tax costs and power bills. In fact, the potential savings are significant enough that progressive cities in North America and governments in other advanced countries have wisely begun requiring green roofs as a matter of public policy.
Properly constructed, green roofs last significantly longer than regularly constructed flat roofs because the plants used to vegetate the roofs protect the roofing material from the baking effects of the sun, and moderate the effects of winter cold. Roof vegetation also helps absorb and divert rain from storm-water runoff systems. It also reduces a building’s contribution to the “heat island” effect in cities. Those are hugely significant benefits. (For more savings, building owners often store rain-water in cisterns to serve roof-irrigation systems, gardens and gray-water use.)
Chattanooga, for example, has had to raise its stormwater fees and on-site stormwater retention requirements substantially because of the costs associated with treatment and overflow of the city’s combined stormwater and sewer system.