Featured Research

from universities, journals, and other organizations

How 'living roofs' help build better cities

Date:
June 9, 2014
Source:
Virginia Tech
Summary:
With more people moving into cities, architects need tools to make good decisions about green roofs. An architectural researcher said with weather extremes becoming unpredictable, vegetated roofs build resilience into a changing world.

The green roof atop Atlanta City Hall offers an amenity to city residents while also providing stormwater runoff reduction benefits.
Credit: Elizabeth Grant/Virginia Tech

Hot town, summer in the city -- it's nothing new, but ways to handle the heat, humidity, and stormwater haven't changed much since the invention of the sewer system.

Related Articles


One solution offered by architectural researchers is known as a "green roof" -- a roof covered in living, growing plants to soften the effects of heat, flooding, noise, and stormwater runoff.

Elizabeth J. Grant, an assistant professor of architecture and design at Virginia Tech, will present ways for architects to determine the most effective depths of green roofing for stormwater control on Thursday at the International Conference on Building Envelope Systems and Technologies -- also known as ICBEST -- in Aachen, Germany.

"With growing numbers of people moving into cities, it is crucial to give architects and builders tools to make good decisions about green roofs," Grant said. "These systems are on the rise not just because they represent a link to the natural world that is scarce in the city, but because they work. Extremes of temperature and rainfall are becoming unpredictable as climates change, and vegetated roofs help us build resilience in a rapidly changing world."

With Kenneth Black and Jim Jones of the School of Architecture + Design, the team generated equations that can predict the effectiveness of vegetated roof installations to control stormwater runoff relative to temperature, humidity, and frequency of sunlight and rainfall.

Green roofs use the sun to transform water into water vapor, which provides cooling as a byproduct. In the same way, these vegetated roofs reduce stormwater runoff and flow rates, which in turn helps prevent sewers from overflowing and stream banks from eroding.

"Our research should give architects and designers justification that they are helping the environment by incorporating green roofs in their plans," Grant said. "We are bridging the gap between science and design."

The researchers built a variety of test platforms with depths of green roofing ranging from about 2.5 inches to 6 inches deep at the Research and Demonstration Facility managed by the College of Architecture and Urban Studies in Blacksburg, Virginia.

Alongside the platforms were a weather station and a rain gauge to measure rainfall, temperature, humidity, wind speed and direction, and solar radiation.

Of 74 rainfall events included in the study, all of the treatment platforms, including the unplanted, growing-medium-only roof, retained significantly more runoff than a white reflective roof membrane with no vegetation or growing medium used for comparison.

Deeper platforms hold more stormwater runoff, but overall green roofs retain about 50 percent of the stormwater compared with about 6 percent for the normal, flat roof.

Light colored roofs or reflective roof surfaces have also been mentioned as solutions to sweltering city temperatures, but recent studies warn that they may merely redistribute heat without reducing it, and they don't address runoff problems as well as vegetated roofs.

The next step in the research is to analyze the data at five-minute intervals to compare the delays in runoff at the treatment platforms, which is important for understanding sewer-system loads and stream erosion.


Story Source:

The above story is based on materials provided by Virginia Tech. The original article was written by John Pastor. Note: Materials may be edited for content and length.


Cite This Page:

Virginia Tech. "How 'living roofs' help build better cities." ScienceDaily. ScienceDaily, 9 June 2014. <www.sciencedaily.com/releases/2014/06/140609205021.htm>.
Virginia Tech. (2014, June 9). How 'living roofs' help build better cities. ScienceDaily. Retrieved October 30, 2014 from www.sciencedaily.com/releases/2014/06/140609205021.htm
Virginia Tech. "How 'living roofs' help build better cities." ScienceDaily. www.sciencedaily.com/releases/2014/06/140609205021.htm (accessed October 30, 2014).

Share This



More Earth & Climate News

Thursday, October 30, 2014

Featured Research

from universities, journals, and other organizations


Featured Videos

from AP, Reuters, AFP, and other news services

Deadly Mudslide in Sri Lanka Buries Houses

Deadly Mudslide in Sri Lanka Buries Houses

AP (Oct. 29, 2014) A mudslide triggered by monsoon rains buried scores of workers' houses at a tea plantation in central Sri Lanka on Wednesday, killing at least 10 people and leaving more than 250 missing, an official said. (Oct. 29) Video provided by AP
Powered by NewsLook.com
Galapagos Tortoises Bounce Back, But Ecosystem Lags

Galapagos Tortoises Bounce Back, But Ecosystem Lags

Newsy (Oct. 29, 2014) The Galapagos tortoise has made a stupendous recovery from the brink of extinction to a population of more than 1,000. But it still faces threats. Video provided by Newsy
Powered by NewsLook.com
Saharan Solar Project to Power Europe

Saharan Solar Project to Power Europe

Reuters - Business Video Online (Oct. 29, 2014) A solar energy project in the Tunisian Sahara aims to generate enough clean energy by 2018 to power two million European homes. Matt Stock reports. Video provided by Reuters
Powered by NewsLook.com
Obama: The US Will Not 'run and Hide' From Ebola

Obama: The US Will Not 'run and Hide' From Ebola

AP (Oct. 29, 2014) Surrounded by health care workers in the White House East Room, President Barack Obama said the U.S. will likely see additional Ebola cases in the weeks ahead. But he said the nation can't seal itself off in the fight against the disease. (Oct. 29) Video provided by AP
Powered by NewsLook.com

Search ScienceDaily

Number of stories in archives: 140,361

Find with keyword(s):
Enter a keyword or phrase to search ScienceDaily for related topics and research stories.

Save/Print:
Share:

Breaking News:

Strange & Offbeat Stories


Plants & Animals

Earth & Climate

Fossils & Ruins

In Other News

... from NewsDaily.com

Science News

Health News

    Environment News

    Technology News



    Save/Print:
    Share:

    Free Subscriptions


    Get the latest science news with ScienceDaily's free email newsletters, updated daily and weekly. Or view hourly updated newsfeeds in your RSS reader:

    Get Social & Mobile


    Keep up to date with the latest news from ScienceDaily via social networks and mobile apps:

    Have Feedback?


    Tell us what you think of ScienceDaily -- we welcome both positive and negative comments. Have any problems using the site? Questions?
    Mobile: iPhone Android Web
    Follow: Facebook Twitter Google+
    Subscribe: RSS Feeds Email Newsletters
    Latest Headlines Health & Medicine Mind & Brain Space & Time Matter & Energy Computers & Math Plants & Animals Earth & Climate Fossils & Ruins