Green Infrastructure or blue-green infrastructure is a network providing the “ingredients” for solving urban and climatic challenges by building with nature. The main components of this approach include storm-water management, climate adaptation, less heat stress, more biodiversity, food production, better air quality, sustainable energy production, clean water and healthy soils. Nature can be used to provide important services for communities by protecting them against flooding or excessive heat, or helping to improve air, soil and water quality. Green infrastructure also serves to provide an ecological framework for social, economic and environmental health of the surroundings. High-performing green spaces can provide real economic, ecological and social benefits such as Urban forestry in an urban environment can supplement managing storm water and reduce the energy usage costs and runoff in result. Bio-retention systems can work to create a green transportation system.
A study in 2012 that focused on 479 green infrastructure projects across the United States, found that 44% of green infrastructure projects reduced costs compared to the 31% that increased the costs. The most notable cost savings were due to reduced storm-water runoff and decreased heating and cooling costs. Ideas for green urban structures began in the 1870s, with concepts of urban farming and garden allotments.
There are mainly three types of green infrastructure:
Urban forests: Urban forests are forests located in cities. Urban forests use appropriate tree and vegetation species, instead of noxious and invasive kinds, which reduce the need of maintenance and irrigation. In addition, native species also provide aesthetic value while reducing cost, it was found that urban trees can provide up to 47% energy savings.
Constructed wetlands: Constructed wetlands are manmade wetlands, which work as a bio-filtration system. They contain wetland vegetation and are mostly built on uplands and floodplains. Constructed wetlands try to replicate natural wetland ecosystems. They are built to improve water efficiency and water quality.
Green roofs and green walls: Green roofs improve air and water quality while reducing energy cost. The plants and soil provide more green space and insulation on roofs. Green roofs also help reducing city runoff by retaining rainfall.
In planning an approach, The Green Infrastructure approach analyses the natural environment in a way that highlights its function and subsequently seeks to put in place, through regulatory or planning policy, mechanisms that safeguard critical natural areas. Plans may be propose how these can be put in place through landscaped and/or engineered improvements. Within an urban context, this can be applied to re-introducing natural waterways and making a city self-sustaining particularly with regard to water, for example, to harvest water locally, recycle it, re-use it and integrate storm-water management into everyday infrastructure. In result, high performing green spaces work to create a balance between built and natural environments.