A report called Cities Alive: Green Building Envelope, reviews green infrastructure schemes across five global cities; London, England; Los Angeles, California; Berlin, Germany; Melbourne, Australia and Hong Kong, China to quantify the benefits of green building envelopes. It is the fourth report in the ‘Cities Alive’ series which looks at ways to help shape a better world.
The report shows that the contribution of green building envelopes, such as moss and vegetated walls, vertical farming and roof gardens, has been underestimated.
Worldwide, 3.7 million premature deaths in 2012 were attributed to exposure to poor air quality. Approximately 200,000 of these were in Europe and 900,000 in Southeast Asia.
Green envelopes, often dismissed as “architectural window dressing,” can reduce localized air pollution by up to 20 per cent in some locations, rapidly reducing toxic air at street level.
Advanced computer software was used to provide a visual representation of the flow of gasses, and help determine the effectiveness of green building envelopes to reduce pollutant concentrations. The report highlights plant species, such as pine and birch, which are particularly effective because of their ability to capture large quantities of particulate matter, including during winter when pollution concentrations are highest.
The study also highlights that green envelopes can reduce sound levels from emergent and traffic noise sources by up to 10 decibels in certain situations. To the human ear, this could make traffic sound half as loud. Increasing the quantity of vegetation in a city can also reduce temperatures. According to a U.S. study, urban areas with a population exceeding 1 million can be up to 54 F warmer in the evening than surrounding areas, and in particularly dense centers, green infrastructure could reduce air temperature by up to 52 F. Green envelopes can also reduce peak energy consumption in traditional buildings by up to 8 percent.
As cities become more densely populated and increasing pressure is put on existing parks and open spaces to make way for further development, the report shows how green buildings can play a significant part in reducing urban stress and keeping people connected with nature. Vertical and urban farming are also highlighted as great ways of being able to create community spaces.