Urban Metabolism

Understanding the theories and research behind the urban metabolism of a city is essential for those in the planning field profession. This is because urban metabolism will aid planners and policy-makers in making effective decision-making and policy-planning in regards to sustaining the environment (especially the urban environment) for the present and future generations.

Urban metabolism is defined as “…the sum total of the technical and socioeconomic processes that occur in cities, resulting in growth, production of energy, and elimination of waste” (Kennedy et al, 2007, p. 44). There are several key factors that should be measured in calculating the urban metabolism in order to describe the resource consumption and waste generation of the Auckland region. They include water, materials, energy and nutrients. Water is considered as the largest component of urban metabolism. Most of the water output within a city is discharged as wastewater (Kennedy et al, 2007). This is evident in studies conducted in several cities which show that wastewater is represented between 75 percent and 100 percent of water inflow; hence, the water component impacts the sustainability of a city substantially. Another factor that is significant when calculating urban metabolism is materials. In particular, construction materials are significant in the development of infrastructure within a city. Although it is proven that cities have become material-intensive, the amount of construction waste generated depends on the city’s recycling schemes (Kennedy et al, 2007). On the other hand, energy is another significant component of urban metabolism that has been studied comprehensively. Transportation energy is the main source of anthropogenic energy outflow of a city. This is due to the increasing transport demand as the urban sprawls away from central business district due to the pressures of population increase (Kennedy et al, 2007). There are however other forms of energy consumption that should be measured within a city such as energy used for heating and cooling, while the effect of ‘urban heat island’ is also significant in terms of quantifying energy balance of cities (Kennedy et al, 2007). Lastly, the flow of nutrients is another significant component of urban metabolism as it is essential in measuring urban sustainability of a city (Kennedy et al, 2007).The most common source of nutrients within the urban environment is from agricultural fertilisers which are accumulated in either soils or groundwater (Kennedy et al, 2007).

Different stages of development or age of the city influence the metabolism rate of the cities. As population increase and cities grow from small settlements, there are changes to the water, materials, energy and nutrients components of urban metabolism. An example is the relationship between urban activities and the underlying aquifers varies depending on the extraction and addition of water which then affects the water table of a city. Increased extraction of water due to increasing demand for water often results in overexploitation of ground water while increasing population also means that there are increases to discharges of wastewater therefore results in ground water being polluted, hence the metabolism rate of a city increases (Kennedy et al, 2007). Kennedy et al (2007) argues that as the city evolves, ground water can either be exploited or could potentially cause flooding of the urban environment. On the other hand, the flow of energy and outflow of construction waste within a city intensifies as the city evolves. This is because as cities grow, so does transport and building infrastructure therefore the quantity of materials and energy used are also increasing, hence increasing the metabolism rate of a city. As argued by Kennedy et al (2007), “...city is like a plant stretching its roots out further and further until its resource needs are met...” (p. 51). This quote is significant because as cities grow older and bigger, the quantity of energy production & consumption and elimination of wastes increases therefore metabolism rate increases.

Urban metabolism is considered as a measure of energy and material flows that are significant in measuring urban sustainability of a city. Ministry for the Environment (MfE) (2008) argues that the use of the urban metabolism approach is vital in understanding how urban areas can contribute to local and global sustainability. This is because urban metabolism provides us with “...insights into what shapes, regulates and governs the flow of inputs and outputs to and from cities” (MfE, 2008). It is important for the local authorities, planners and policy makers in Auckland to understand the physical, biological and human basis of the region through the urban metabolism approach. This is to ensure that they are using resources efficiently and to what extent theses resources are close to exhaustion (Kennedy et al, 2007). By gaining knowledge of Auckland’s metabolism rate, the local government can focus on how to minimise the adverse impacts of increasing urban activities on the environment, hence aid in the development of sustainability initiatives and strategies to slow the exploitation of the natural and physical resources (MfE, 2008; Kennedy et al, 2007).

Sahely et al (2003) indentified several constraints and limitations on the use of an urban metabolism model for informing understanding of urban sustainability. They are:

• There are concerns over the commensurability of data from different cities, particularly for waste streams.
• Limitations on the accuracy and availability of the data.
• Measurements of reliance on the imports available.
• Assumptions made particularly on the calculations of food consumption. It is important to consider that cultural differences and spending will result in the outliers in the data.
• Urban metabolism is focused more on the physical and biological factors within a city. The significance of considering social and economic factors when undertaking an urban metabolism study should be stressed by urban policy makers.
• There is no measurement on the liveability of a city.

Apart from the importance of an urban metabolism study in highlighting future problems and trends in using the environment, there are other factors that should be considered in developing an urban sustainability network in Auckland. Socio-economic factors such as the measurement of human welfare and social conditions should be considered as it gives an insight on what the society will need in the future. The understanding of the differences in culture is also an important factor to consider when developing an urban sustainability network as different cultures will have diversifying needs. Technology and innovations is another factor that plays a huge part in promoting sustainable development. And lastly, the differences in the geographic location and climate variations of cities should be considered. Through incorporating all these factors mentioned above, improvements can be made by treating the economy, environment, society & culture and technology as a whole in terms of developing an urban sustainability framework and promoting sustainable practices in the management of the natural and physical resources (MfE, 2008).

References:
Kennedy, C., Cuddihy, J. And Engel-Yan, J. (2007) The Changing Metabolism of Cities, Journal of Industrial Ecology, 11: 2, 43-59.
Ministry for the Environment, (2008) Characteristics of sustainable and successful urban areas, http://www.mfe.govt.nz/issues/urban/sustainable-development/characteristics-areas.html, (date accessed: 26/05/2010).
Sahely, H., Dudding, S. and Kennedy, C. (2003) Estimating the urban metabolism of Canadian cities: GTA case study, Canadian Journal for Civil Engineering, 30, 468-48.

PRT - sustainable transportation option in the future?

Personal Rapid Transit (PRT)

As described further by the video above, PRT, also known as a podcar (typically a four-seater) is a public transportation system designed to work as an automatic vehichle on a network of specially-built guide ways. They are designed to make a non-stop journey to the individual's selected destination. Heathrow will host the world's first PRT trial; this system would bring significant benefits such as the provision of a quick and comfortable service and also contributing to improved environmental benefits.

Key features of PRT include:

• Energy efficiency - 4 times less energy usage compared to an average car.


• No pollution and/or less pollution generated as electric power plants are getting cleaner with development of renewable sources.


• Faster travel time - 3.5 times faster than a normal bus and 2-3 times faster than an automobile.


• Safer than other forms of transport due to automation, moderate and constant speed, operation on rails, no fuel on board, redundant design and seperation from pedestrians.


• Light wieght - less than 600kg (half the weight of a small automobile).


• Initial cost is high but it is considered to be cheaper in the longer term as they have a longer life span than an average car due to very few moving parts.


• Takes up a very small area of land and there is no need for car parks. 0.02% of land use compared to 30% for the automobile.


• Convenience - 24 hour service and the ease of use.

I reckon we probably will see more of PRTs installed all over the world if the Heathrow trial run is successful. I believe that this could be a start to building sustainable urban environments as it will minimise congestion and lead to the improvements of the air quality (less ghg emissiions).

Check this website for more details on PRT http://www.personalrapidtransit.com/. It's pretty impressive what PRTs can do :)

HOME - must see documentary!

Home is a 2009 documentary directed by Yann Arthus-Bertrand. It is about how human activities are threathening the ecological balance of the earth. The main theme that is stressed throughout the film is how the Earth is a system and therefore all living things form a mutual relationships with each other. However, due to the pressures of population increase and intensifying resource consumption, with a focus on global warming, the ability for the planet to sustain us is threatened. The film concludes that action should be taken now and shows several examples of how various countries are dealing with these impacts through sustainable development practices.

I recommend this documentary to everyone especially to planners as it highlights the harsh realities of how we are impacting the planet. Hence, planners must develop and implement plans and policies that will mitigate and adapt to the effects of climate change. The aerial shots used in this documentary are also amazing!! Highly recommended!! *****

For those who are interested in watching the full video, here's the link: http://www.youtube.com/watch?v=jqxENMKaeCU

Metropopular

There are very few cartoons and animations existing that can be used to explain planning issues and concepts. However, I found this really interesting animation called 'Metropopular' whilst browsing on the net.

Metropopular is about a popularity contest for a number of American cities. "It looks at the best and worst charactersitics of American cities from the cities' own perspective". I found this cartoon very entertaining and quite funny, hence I recommend you guys to watch it if you have spare time

Here's the video for those who are interested!

Images of Earthsong Eco-Neighbourhood

Here are a few photos that I took from the trip:

Typical 3-bedroom dwelling within the neighbourhood

Shared community open-space

Solar panels installed in each of the dwelling's roof

Stormwater pond

2-bedroom apartment complex

Plantings along the footpaths adds to the amenity

Trip to Earthsong Eco-Neighbourhood

As part of the Planning 403 Housing course, we visited New Zealand’s first cohousing neighbourhood, located in Waitakere City, West Auckland. Earthsong Eco-Neighbourhood’s vision is “to establish a cohousing neighbourhood based on the principles of permaculture that will serve as a model of a socially and environmentally sustainable community”. Resource consent was granted for the 1.67 hectare site in 1999 where a consensus decision-making process was adopted by the community in creating an innovative urban housing development. Construction of the first few houses started in 2000 and all 32 homes were completed in 2006. The homes in Earthsong promotes sustainable living as the houses were constructed using rammed earth, timber and non-toxic materials, and were designed to incorporate passive solar principles (warm in winter, cool in summer). On the other hand, Earthsong also promotes environmental sustainability as permaculture “…minimises environmental impacts by reducing stormwater runoff and encouraging self-sufficiency in water consumption, energy use and food production”. The housing arrangement in Earthsong is also significant as it is designed in a way that it encourages social sustainability. Community living is enhanced through having shared facilities such as the ‘Common house/Earthsong Centre’; having weekly common meals; and through a pedestrian-friendly environment.

I found the trip to the Earthsong eco-village very interesting and educational not only because it is the only cohousing community in New Zealand, but it also gave me a first hand insight on what an urban eco-neighbourhood is like. The trip definitely increased my understanding of sustainability in terms of demonstrating and promoting innovative community design and environmentally responsible construction. After the trip, I’ve now become more open-minded that creating socially and environmentally sustainable communities is possible if everyone in the community works together to achieve one goal. Adopting a consensus decision-making process is significant as it gives everyone in the community a fair and equal opportunity in making decisions towards achieving the community’s main vision.

There are however questions and issues that arise from the Earthsong Eco-Neighbourhood type of urban development in terms of adopting it within the New Zealand context. Firstly, will this type of housing arrangement work in a larger-scale community in New Zealand? Will most people living in New Zealand accept cohousing? How can we change the mentality of most people in order for them to accept and be open-minded about promoting community living? In what ways can we promote a social and environmental sustainable community in New Zealand?

In my opinion, I think that the idea of a cohousing development will not fit in the context of a larger scale community development in New Zealand. This is because I think that in order for a cohousing development to be successful, the people within the community must have fairly similar values and outlook on life and what kind of lifestyle they have. Hence, it would be very difficult to promote a cohousing type of community living in terms of building large-scale communities due to people’s conflicting views and stances. However, cohousing should definitely be encouraged in building small-scale communities and/or neighbourhoods in order to promote social sustainability in New Zealand. On the other hand, I think that promoting environmentally sustainable urban environments should not be encouraged. It is important that New Zealand should catch up with other countries on building and developing sustainable homes as not only will it decrease environmental impacts, but also will be economically cheaper in the long-run.

Overall, I think that the development of the Earthsong Eco-Neighbourhood is a big step in terms of promoting environmental and social sustainability in New Zealand. Earthsong Eco-Neighbourhood could serve as a model in creating sustainable communities that encourages a more cohesive and co-operative urban communities.

Planning key words...