For centuries, it hasn’t seemed like much of a problem to dig out the earth, erect structures and cap them with impervious asphalt roofs. But with population growth and ensuing urban development, it has become extremely problematic. Storm-water runoff, flooding, polluted watersheds, violent temperature contrasts, increased heating and cooling energy consumption and costs, gusting winds and stripped habitats are all by-products of the replacement of earth with concrete.
Of these complications, storm-water runoff has been the most challenging. When rain falls on our waterproof concrete jungles it picks up pollutants as it flows off roofs, walls and gutters and runs straight into storm drains and on to its final destination - our lakes, rivers and oceans. With nothing to slow down heavy downpours, wastewater systems flood, dumping raw sewage into local bodies of water.
The other major problem to contend with is the urban heat-island effect. Asphalt rooftops can reach 150oF, contributing to warmer temperatures in cities than their surrounding regions - a 10o difference in some areas. This translates to higher energy consumption and costs to cool buildings.
How to mitigate these environmental extremes is something city planners and architects worldwide have been grappling with for years. The solution? Green roofs!
Green roofs, also called living roofs, solve the flooding and water pollution problems by mimicking meadows. Soil composites and vegetation absorb water, filter and cleanse it, slow it down, and even store some of it for use during dry spells. They help the energy consumption quandary by acting as insulation thus reducing energy costs by as much as 20%. They even improve air quality by absorbing carbon dioxide. Water savings also come in to play in buildings where rainwater is collected and reused for watering exterior plants or flushing water for toilets.
Stay on top of the news of the day
Subscribe to our free, daily e-newsletter to get Milwaukee's latest local news, restaurants, music, arts and entertainment and events delivered right to your inbox every weekday, plus a bonus Week in Review email on Saturdays.
Not as quantifiable, but just as important, is the many aspects of beauty and relaxation that green roofs provide. Supplementing the environmental and economic incentives to implement green roofs, is a shift in consciousness that is taking place in society today. People no longer want their cities to be the antithesis of nature. They want to work and live in a place that is beautiful, alive and healthy.
When looking out over the city from your office or apartment would you rather see a sea of gray or green? If you need a break and some fresh air would you prefer to walk out to the hustle and bustle of the city streets or head up to the tranquility of your green roof. Do you want to live and work in a city that is lifeless or one that is populated with several species of birds, trees, flowers and plants?
Urban garden and landscaping projects abound at ground level. It’s time to take it to the skies where thousands of acres of potential green space awaits. Green roofs can be installed on any scale - from a bus shelter to a cottage to a Walmart.
Consider adding one to your home. The installation costs will be outweighed by energy savings and the extension of your roof’s life.
In depth list of green roof benefits
Take a tour of the Milwaukee Public Library’s green roof
Here are some examples:
A Green roof bus shelter in San Francisco
A Portland building:
