Green and Blue Roofs

Water conservation is always a trending topic. In some places this due to a lack of water. In others, it is simply to save money. There are a number of ways to cut costs in the long run with a good design. Green and blue roofs are two examples of ways to conserve water.

As any good landscaping designer will tell you, “green and blue roofs” are rooftop systems that help manage storm water drainage in addition to many other benefits. They both offer an insulating layer on top of a roof to help trap energy in the winter and reflect sunlight in the summer. And, both of these options help manage storm water. They do so by gathering it as rainfall and releasing it gradually over time.

What’s the difference?

The difference is that green roofs offer an opportunity for biodiversity and food production. Although, the water gathered by blue roofs can be used for irrigation, cleaning sidewalks or reducing potable water use by filling washing machines or toilets.

Green roofs are a vegetative layer that grows in a specially-designed soil. Specific soil is needed in order to not sink the roof or cause damage due to weight. This soil sits on top of a drainage layer. Green roofs are more costly than conventional roofs but they are capable of absorbing and retaining large amounts of storm water.

blueroofUnlike green roofs, blue roofs are non-vegetated systems that help control storm water drainage. Wires along the roof and drain can create temporary ponding and control a gradual release of storm water. Blue roofs are less costly than green roofs. Coupled with light colored roofing material they can provide sustainability benefits through rooftop cooling.

What are the Benefits?

There are many benefits to green and blue roofs.

Green roofs last longer than conventional roofs and create natural installation, which reduces energy costs. In replacement of the unused harsh looking roofs, green roofs create peaceful retreats for people and animals. Because of the greenery, living roofs contribute to storm water management. Green roofs improve air quality. And, they are being implemented to help fight the Urban Heat Island Effect. This is a condition in which city and suburban developments absorb and trap heat.

green-roof2There are also many benefits to blue roofs. Blue roofs require no additional land area, so they work well in areas that need the water management the most. In addition, they are easy to install and maintain. Although it is an additional cost, blue roofs cost considerably less than other measures. Blue roofs also provide similar storm water benefits as green roof and have a low carbon footprint.

For designers, both blue and green roofs offer elegant solutions for property owners that can offer benefits and savings into the future.

A Green Blue Roof

A green and blue combination roof system was recently designed for a building in New York City. Initially, there was concern about the added weight to the roof.

To limit the additional weight a tray system for both blue roof and green roof elements was used. This system allowed for easy distribution of the additional weight to spaces on the roof that could bare more. Designers are expecting, with proper maintenance, the rooftop system to outlast the life of the roof membrane, in excess of 30 years. The tray system also enables repairs, tray replacement and a change of weight distribution if needed.


Leave a Comment