Eco-friendly green roof an age-old concept

Recent years have seen a clear and defined shift to a more ecologically conscious building industry. More and more people are looking for products and technologies that not only effectively do the job they are meant to do but also reflect an eco-friendly awareness when doing it. The construction industry is responding.

There's no question that technological advancements in the building industry are allowing us to do more with less and are giving us more ecologically minded options but many of the green building advancements we see today are being created by the simple reintroduction of building practices that have existed all along.

Case in point: the green roof.

The green roof or "living roof" is commonly recognized as a modern, environmentally conscious alternative to a standard asphalt roof but the notion of having contemporary beginnings couldn't be further from the truth.

Archaeological findings on the northern tip of Newfoundland have unearthed the remains of Lief Eriksson's ancient Norse settlement and point to the use of sod roof dwellings by Viking explorers over a thousand years ago.

This is no surprise of course as it was a common building practice for the Scandinavians of yore to use sod atop structures of heavy timber and birch bark to create effective insulating and water resistant roof systems. For these ancient people, the green roof was a simple and effective sheltering system created from building materials that were readily at hand. The green roof as we know it today is clearly different from the sod roof of the past but the fundamental concept behind the two remains the same.

What we define as the "modern" green roof -- the integration of a growing medium over a waterproof roof membrane with the deliberate intent of supporting vegetation growth -- was first developed in Germany in the 1960s.

German designers were first drawn to the idea of a living roof purely along esthetic lines recognizing that the incorporation of a growing medium atop a building's roof would enhance the beauty of the building. But in 1970, the German landscape architect Hans Luz challenged this perception by suggesting that a green roof was far more than a simple decorative covering but rather a feature that would profoundly improve the quality of the urban environment. Today, more than 40 years later, the green roof has finally received mainstream recognition as an ecologically minded system that adds to any sustainable urban management plan.

The modern green roof possesses many benefits that make it an excellent environmentally conscious alternative.

A green roof greatly increases the insulating capacity of a roof system while protecting the waterproof membrane of the roof below. The added mass and thickness of the system provides for excellent sound insulation as well.

Storm-water runoff is greatly decreased by a living roof as the growing medium and vegetation retain large amounts of water that can be released back into the environment at a more manageable rate.

Much of this moisture is released through the process of evaporation which, in itself, creates a cooling effect that helps reduce the urban heat-island phenomena that is so common in our cities today. The large-surface tar and gravel roofs that blanket a typical city roofscape absorb solar radiation and re-emit it back into the city as heat. There's a reason cities are significantly warmer than the areas that surround them. A green roof helps reduce this heat gain.

A living roof is exactly that, a natural surface that provides a habitat for birds and insects while acting as a carbon sink by drawing carbon dioxide out of the air.

As we move forward to create a more ecologically friendly future we might be surprised to find that some answers lie in the past.