Mid Sem-2 Planning Green Cities

Cities are becoming more crowded, hotter and noisier and heatwave due to climate change strains human health, infrastructure, productivity and urban amenity. This often result in an expensive solution of air conditioning, that creates more pollution, noise and hotter outdoor spaces. Green infrastructure including green roofs, green walls, vegetated surfaces and street trees is an obvious solution that has been increasingly implemented in several cities all over the world. The Australian government has recognized and placed an agenda for it as part of Clean Air and Urban Landscape hub in National Environmental Science Program to green cities.

Hard surfaces, such as asphalt, concrete and stone that is common in cities, increase urban temperatures due to heat absorption and radiation back into the air. This can be solved by green infrastructure that regulates ambient air temperatures better. Street trees can lower surrounding temperatures up to 6℃ or 20℃ over roads. Additionally, foliage creates local cooling by evapostranspiration, in which the plants release water vapour into the surrounding air.

Green roofs and walls can cool buildings naturally, essentially decreasing air conditioning. Green infrastructure can improve storm water management and urban aesthetics, and provide habitat for wildlife and recreational activities for people. They also provide shade, take in carbon dioxide and decrease noise levels.

Although there are multiple benefits of urban greening, the Urban Developer's research shows that the planners are very cautious. The planners cautioned about uncertainty in delivering the technology The biggest obstacle was the inexperienced planning department in dealing with green infrastructure. They usually avoid it since it is not traditionally part of planning agendas and can create economic, environmental, institutional, legal and social issues.

It is further explained that it is hard to choose appropriate forms of vegetation based on drainage capacity, prevailing climatic conditions and species growth patterns. The root systems could damage underground utility networks and buildings, the trees might damage houses in a storm and the roofs needs to be strong enough to support rooftop gardens, which means external experts' advice is required. The socio-political barrier includes governance concerns, for example the political context of planning decision-making. Furthermore, management problems were of government's commitments to budget for green infrastructure delivery and management. Lastly, "public sentiment about green infrastructure can be influenced by perceptions of modified access, changed use or loss."

It is urgent to bring in the urban green infrastructure into the cities as they are getting hotter due to climate change. The research indicates that green infrastructure should be mandatory as an urban feature so the planners should collaborate with other government departments, residents and utility companies. They also need to manage stakeholder's expectations and ensure sharing cost where needed. Innovative solutions are needed for economic, environmental, legal and social challenges. As the planners increasingly provide green cities, they need to know its value and be prepared to lead and learn from new problems and solutions encountered for the habitability and urban comfort of urban residents.

Resources
http://www.theurbandeveloper.com/green-cities-urban-greening/