Green tech needed as CO2 emissions increase

Green tech needed as CO2 emissions increase

 

Carbon dioxide levels in the northern hemisphere hit 400 parts per million for the first time in human history, according to an article by the Sydney Morning Herald.

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The Future of Cityscapes Depend on Green Infrastructures

Green Infrastructures

An investigation by a research group called The Resilience of Cityscapes, published in the international Biotope City journal, showed that green roofs, living walls, and greened permeable pavements has a multitude of positive effects.

“The impact of green infrastructure on an urban fabric has been visualised by computer modeling tools. The computer model results showed that all tested green technologies provide benefits to the urban microclimate and water storage capacity,” the report said.

It showed that green infrastructure is the solution to the resilience of cityscapes worldwide. The report said there is a huge trend in urbanisation with more than 50 percent of the world’s population now living in cities.

“Two effects of this influx can be observed: the occupied city area grows and
density increases. At the same time citizens request more infrastructure from cities such as public transport, recreation and sewage systems. City planners are challenged to combine the pressure of growth and integration of satisfactory infrastructure.”

The research monitored 14 green roofs, five living walls and nine surface consolidation methods in the city of Vienna to see their microclimatic effects.

Compared to surfaces like plaster or brick, plants convert sun energy into oxygen and air humidity.

“It is assumed that plants ameliorate the urban microclimate (by adding humidity and reducing radiation and wind speed) while regular surfaces
reduce the thermal comfort of cities. Aside from the positive microclimatic effects plants are also able to store water.”

Plants also improve the predicted mean vote (PMV), which describes the human thermal wellbeing. The research tested an urban area in Vienna under different types of “scenarios”. These include the climate scenario, greening scenario, the minimum greening scenario, and the maximum greening scenario.

The tests found that green infrastructure can act as a buffer for climatic extremes.

“By means of computer simulation, the measurements at test sites have been transferred to representative urban typologies of the City of Vienna. To find out, which microclimatic effect could be achieved by green infrastructure, two greening scenarios have been applied on urban typologies and subjected to today’s and future climatic framework conditions. The simulations make clear, that the urban microclimate can be ameliorated by integration of green infrastructure.”

It emphasised that green infrastructure is the “one appealing solution to improve the resilience of cities against climate change”.

“Apart from the microclimatic effects and the positive influence on thermal comfort, green infrastructure provides a broad range of added values: water retention, health promotion and psychological effects (stress reduction), habitat and habitat connection for fauna and flora, biodiversity and urban farming.”

The report also realised the hindrances to the implementation of green infrastructures such as different types of value on facades where some are often protected. There are also things like different regulations in different cities or the fact that most buildings are privately owned and therefore needs incentives for their properties to be developed into green infrastructure.

These are things that need to be overcome as the report also said that just a single green infrastructure would not be effective in the bigger scheme of things. In order to have the full effect of the benefits of green infrastructures in cityscapes, “a combination of different types of green infrastructure and a network of green infrastructure throughout the city is necessary”. CTA_Full Treepit Library

Benefits of Green Roofs, Walls and Facades

Benefits of Green Roofs, Walls and Facades

Image from Fytogreen. This is Fytogreen’s vertical garden project in 1 Blight St, Sydney.

Winter is coming to Australia and with the cold weather comes heating costs. However, heating costs may soon be a thing of the past with an alternative greener concept.

Victoria’s Growing Green Guide, a project by The University of Melbourne, The Inner Melbourne Action Plan and several industry experts, is pushing for green roofs as a more cost-effective alternative to answer heating needs.

The guide provides technical advice on how to design, build and manage green roofs, walls and facades so they can provide multiple benefits over a long period of time.

According to the guide, green roofs, walls and facades provide several benefits to the community and its residents. Here are some excerpts from the report:

  • Building owners and developers are increasingly installing green roofs, walls or facades to add a point of difference, increase commercial returns, provide visual appeal and turn a building into a local landmark. It increases property value as well as other benefits for building owners. Green roofs can lengthen the lifespan of a traditional roof surface. They protect a roof’s waterproof membrane from solar radiation and add insulating materials to reduce severe temperature fluctuations on the roof surface. The report says early design discussions will help ensure that the roof, wall, or façade can be planned and incorporated in other building aspects such as drainage, irrigation, lighting and weight loading.
  • Green roofs absorb and retain rainwater and can be used to manage stormwater run-off in urban environments. They can also filter particulates and pollutants. Stormwater run-off can be reduced or slowed because it is stored in the substrate. Additional water storage capacity in green roof systems can be provided through incorporation of a water retentive layer or drainage layer at the base of the green roof.
  • It reduces building heating and cooling requirements. Green walls and facades can reduce heat gain in summer by directly shading the building surface. Green roofs reduce heat transfer through the roof and ambient temperatures on the roof surface, improving the performance of heating, ventilation and air conditioning (HVAC) systems.
  • Green walls, roofs and facades reduce the urban heat island effect. Temperatures can be reduced by covering a roof or wall with a layer of vegetation that shades building materials, which would otherwise absorb heat. Evapotranspiration provides cooling effects, as water is evaporated from the soil and plants transpire by taking water in through roots and releasing it through leaves. The report suggests a city-wide strategy to implement green roofs, walls and facades to help mitigate some of the negative consequences of the UHI effect.
  • Green roofs can contribute to and enhance biodiversity by providing new urban habitats and specific habitats for rare or important species of plants or animals. It can also provide a link or corridor across urban ecological deserts and assist in migration of invertebrates and birds.
  • These green infrastructures can increase amenity and provide opportunities for food production, recreation, relaxation or commercial ventures. Green roofs, walls and facades can be used for multi-level greenery designs that connect with ground level green spaces.
  • Finally, they also contribute to the removal of gaseous pollutants from the air. Plants with a high foliage density or with textured leaf surfaces that trap small particles also assist in removing particulate pollution, through dry deposition on the foliage or through rain wash.

The good news is that most building surfaces have the potential for greening. It’s just a matter of knowing how to do it properly to get the most benefits out of it. A copy of the guide is free to view for those interested.

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