The Mandel Center for Nonprofit Organizations was constructed with some “green” technology – literally. The roof has a partial cover of plants that make it appear green from space. Green is also the focus of the Tinkham Veale University Center, which is scheduled to break ground this semester and includes an entire roof of plants, known as a vegetative roof.

Vegetative roofs are roofs that are covered in soil and plants. Vegetative roofs are built primarily for the environmental benefits: they help improve air and water quality and control runoff volume. In urban environments, they help reduce the urban heat island effect, lowering the demand for air conditioning by up to 75 percent in the summer.

Vegetative roofs come in three main types: intensive, extensive, and modular block. Intensive vegetative roofs are roof gardens with trees and shrubs chosen for both their environmental and aesthetic value. This adds a considerable amount of weight to the roof – around 80 to 150 pounds per square foot – due to the irrigation and drainage systems required to maintain them.

Intensive vegetative roofs, on the other hand, are built primary for the environmental benefits and are lower in weight, typically around 15 to 50 pounds per square foot. These roofs consist of hardy plants and thick grasses that are only accessible for maintenance.

The last type of vegetative roof is modular block. This type is held within portable units, which are placed directly on top of the roof. Modular block roofs are the most lightweight at around 12 to 18 pounds per square foot. Because they consist of portable units, these roofs are the easiest to use in conjunction with existing roofs on a low budget.

There is another, different type of green roof, called a cool roof. Cool roofs reflect sunlight and heat better than average roofs, and have a high thermal emittance. These factors allow cool roofs to stay 50 to 60 degrees Fahrenheit during the summer. Cool roof technology has been used on Tomlinson Hall and the nursing school’s Health Sciences Center, both of which received a white reflective coat over their black roofs, and we hope to see this technology put to use elsewhere on campus.