Up on the Roof

This week's newspaper column:

Green roofs are the latest thing in sustainable building technology.

Well, not quite.

Planted roofs were around as long ago as the seventh century B.C. when King Nebuchadnezzar adorned roofs with vegetation in what famously became known as the Hanging Gardens of Babylon.

In Scandinavia and Iceland, people have utilized sod roofs to insulate homes from the extreme cold for centuries.

Fast forward to the twenty-first century and green - or “living” roofs - are making a big comeback.

Cities like Chicago and Portland, Oregon are aggressively encouraging the installation of green roofs on as many rooftops as possible. Ford Motor Company’s River Rouge manufacturing plant sports a 10 acre living roof, and you’ll even find a green roof on the Pentagon.

Why?

Green roofs offer a plethora of environmental, economic, and aesthetic benefits.

While conventional roofs bake in the summer sun hiking surface temperatures to well over 100 degrees Fahrenheit, a planted roof remains roughly the same temperature as you would find under a nice shady oak tree. Extreme heat and ultraviolet rays degrade roofing materials, but a roof protected by vegetation typically lasts two or three times as long, and the insulating characteristics of a green roof keep the inside of a building cooler in the summer and warmer in the winter saving energy year-round.

Municipal officials always complain about the ever-increasing costs of storm water drainage systems. Water falling on hard surfaces (such as concrete, asphalt and roofing) rushes into underground drainpipes that must be sized for maximum capacity. Collectively, green roofs (along with planted areas on the ground) relieve the system of that extreme sudden surge of water runoff minimizing the need for costly expansions of underground piping.

Urban spaces act as “heat islands” and are typically several degrees hotter than the surrounding countryside. Planted roofs lower the ambient temperature of the surrounding area while simultaneously improving the air quality as they absorb carbon dioxide and emit oxygen.

And green roofs have aesthetic qualities too, as vegetation softens the hard edge of the built environment. As living roofs grow more popular, they’ve even been utilized as private patio gardens and as bonus public recreational space.

The cost?

Green roofs can be installed for as little as $10 per square foot and can easily be accommodated on new construction. If added to an existing building, it might be necessary to beef up the structure as planted roofs add at least 25 pounds per square foot to the roof load when saturated.

Want more information? Go to www.greenroofs.com or just type in “green roof” on your computer’s browser and you’ll find a wide variety of interesting planted roofs and resources.

Think about a green roof next time you’re planning a building project; the idea is old, but the benefits are timeless.

Update: A link from Robert to an article about a very cool Richard Neutra house with a green roof:

http://www.treehugger.com/files/2009/03/nothing-new-about-green-roofs.php

Green Retrofit

Green design is not just for new buildings. This 100+ year old structure has been enhanced with a series of green building technologies including new energy-efficient mechanical systems and lighting, operable windows resulting in a savings of over $1000 per month on energy costs.

This spring, the solar panels and green roof will be installed. Most of the green roof is a low-maintenance roof using indigenous plants and wildflowers that grow heartily without the need for constant supervision. (Think about the plants you see along the highway that grow just fine without being watered by anyone except mother nature.)

We've carved out a 30' x 90' section for a roof garden and "fair-weather classroom" for the five-and-under year old students served by the agency.

The solar panels will supplement the facility's power needs. The amount of power generated will depend on the level of funding generated for the project over the next few months. In the end, this building will not be entirely energy self-sufficient, but close.

Green Roofs

Its a jungle up there – or at least it could be.

Green roofs have their advantages according to Chicago’s mayor Richard M. Daley.

"As well as saving building owners money, green roofs…improve the environment and contribute to a healthy city," said Mayor Daley. "These are the kinds of things that improve the quality of life in a city. Our trees, flowers, fountains and benches soften the city's rough edges, add some color and make people feel more at peace with the urban environment."

What is a green roof? In essence, a green roof is composed of indigenous plant life and soil over a waterproof membrane – all on the rooftop of a building.

Environmentally, green roofs offer many benefits. The insulated thermal mass keeps building temperatures warmer in the winter and cooler in the summer. Vegetation in an urban environment counteracts the “heat sink” affect of concrete and asphalt. Green roofs reduce storm water runoff; they clean pollutants from the air and pump additional oxygen into the urban environment.

Functionally, planted roofs lengthen the lifespan of the roof and provide extra patio space for the inhabitants. And urban gardens, including herbs and vegetables, make great use of city rooftops.

Structure must be considered in any green roof adaptation. Smaller plant life takes less soil and can generally be installed on most roofs. Larger trees with bigger root balls should be located above existing structural elements (a column or large beam) so the weight can be transferred to the ground.

A few years ago, Chicago started a grant program (up to $5000) to encourage the installation of green roofs across the city. Chicago City Hall sports a green roof installed by the city in 2001. Since then, the city has saved tens of thousands of dollars on energy costs for this building alone.

Here’s a link for Chicago’s green roof program.

http://www.artic.edu/webspaces/greeninitiatives/greenroofs/main_map.htm

And a link to a site devoted to green roofs.

http://greenroofs.com/