Saturday, 27 February 2016

Cities in Motion Index: South African Cities rank 104, 117 and 119th.

The Cities in Motion index has been developed to measure and rank world cities in terms of their future sustainability and standard of living. The index is made up of the following ten criteria:

1. Governance and the People’s Participation
2. Urban Planning
3. Public Management
4. Technology
5. The Environment
6. International Outreach
7. Social Cohesion
8. Mobility and Transportation
9. Human Capital
10. The Economy

The index ranks London, Tokyo and New York in the top three. Cities are also categorised in terms of whether they are Challengers, High Potential, Consolidated or Vulnerable, as shown in the graphic below.

African cities such as Cairo and Johannesburg are classified as Vulnerable and High Potential. South African cities such as Pretoria, Johannesburg, Durban and Cape Town are ranked from 104 to 119, with Durban performing best, and Cape Town, worst.  A review of the spider diagram provided for Pretoria below indicates that reasons for low performance are the poor scores for social cohesion, international impact, human capital, environment and technology.

A review of these criteria reveals that perhaps some of the criteria are loosely named. For instance, social cohesion performance is represented by measuring the number of deaths per 1,000 inhabitants, the Gini coefficient; the unemployment rate, and the consumer expenditure on housing per capita, in millions of constant dollars per inhabitant in 2013. It is not clear how these indicators provide a measure of the social cohesion which is normally defined in terms of trust, consensus or intensity of social interaction within a population.

The basis for the inclusion of criteria is also not explicit. For instance, the indicators for ‘International Outreach’ are thousands of air passengers, number of meetings and thousands of tourists. While ‘International Outreach’ may be a good measure of business or tourism activity it is unclear why this is an indication of future sustainability, as increased air travel is associated with increased carbon emissions rather than improved sustainability. Here, other indicators such as the type and scale of information and communications technology (ICT) available, may more suitable as this enables meetings and economic activity through video conferencing, email and the internet without the carbon emissions associated with travel.

It could be argued that long term sustainability can be enhanced by investing in capability for increased resource efficiency. For instance, investments by cities in better ICT, more energy efficient buildings, improved public transportation and renewable energy can support high levels of economic activity while reducing carbon emissions and pollution at the same time. Criteria that measured this type of capability may be a better indicator of long term sustainability than current business activity. This idea is explored in the development of the BEST and SBAT indicator systems.

More information:

Rainwater harvesting: Playing a valuable role in increasing the resilience and sustainability of water supply

South African is a water scarce country and studies indicate that 98% of available water supplies are already exploited. In addition, a number of South African cities, such as Johannesburg, are vulnerable to water shortages if a severe drought occurs (Department of Environmental Affairs, 2011).

NY Times
Therefore, it is important to understand how water can be used as efficiently as possible and to explore alternatives to municipal piped water supplies. Rainwater harvesting provides a simple way of capturing and storing water which can be used to supplement, or replace municipal water supplies. It can be used to reduce the pressure on municipal systems and provides a valuable buffer for households and businesses against drought and local water shortages.

This article describes how rainwater harvesting can play a valuable role in increasing the resilience and sustainability of water supply. The different types of rainwater harvesting systems are described and advantages and disadvantages of the technology listed. Some of the key design and operational principles are presented to enable the practicality and applicability of systems to be understood. Finally, conclusions are drawn and policy, and other, recommendations are made to support the increased adoption of rainwater harvesting systems in South Africa.

Full article can be accessed here

Water in Sustainable Buildings

Water systems in sustainable buildings are different in a number of ways from conventional buildings. Characteristics of water systems in sustainable building include:

  • Self sufficiency: Sustainable buildings may aim to meet all, or most of their water needs from rainwater harvesting.  
  • Water quality: The quality of water is matched with use. For instance, the best quality water may be used for drinking and cooking and poorer quality water, such as grey water, used for flushing toilets and irrigation. 
  • Onsite retention: In natural environments vegetation and soil absorb and retain a large proportion of rainwater that falls on to it. Sustainable buildings aim to emulate this by ensuring that buildings and sites absorb and retain rainwater on site and avoid generating large quantities of runoff.
  • Evaporation and transpiration: Air can be cooled and the humidity increased through evaporation of water and transpiration from plants. This may be used in sustainable buildings to improve comfort levels without the use of mechanical systems.

More information on water systems in sustainable building can be accessed here. 

Characteristics of Sustainable Building Envelopes

Building envelopes in sustainable buildings are different from conventional buildings in that they aim to achieve a wider range of objectives and work in a different way.

Some characteristics of sustainable building envelopes are:
  1. Responsive: Green building envelopes are designed to respond to their local context and work with external and internal conditions to achieve optimum environments within and around the building. Therefore, the building envelope may have additional acoustic treatment in areas which receive noise from external environments and have strong visual and physical connections (through balconies, windows and external doors) where external light and thermal conditions support human comfort.  
  2. Dynamic: In order to achieve optimum conditions on an ongoing basis, green building envelopes are dynamic and adapt to changing conditions. Thus, more of the building envelope may have shading in summer than in winter to minimise unwanted heat gains. In winter, the envelope may allow more sunlight to enter the building than in summer to allow this to warm the building.  
  3. Controllable: Providing users with greater control over local environments is a central strategy in most green buildings. Building envelopes, therefore, are likely to have large numbers of operable windows that can be easily opened and closed by occupants. They may also have controllable internal blinds and external solar shading which can be used to maximise internal daylight quality and avoid glare and solar gain. 
  4. Ecological: Green building envelopes aim to support the development of ecosystems and plant and animal life around the building. Therefore, the envelope may be used to create habitat for animals such as birds and the roof and balconies may be planted. 
  5. Breathable: Designers of green building often try and achieve the same performance qualities found in good outdoor clothing. The outer layer of the building envelope, like a raincoat and umbrella, provide protection against weather such as wind and rain. The middle layer, like shirts and jerseys, provide warmth and thermal insulation. The inner layer, like a vest, is comfortable to touch and wicks away excess moisture. 
  6. Microclimatic: The building envelope is used to support the development of local microclimates. Thus, envelopes may be used to create sheltered, sunlit spaces around buildings as amenity areas for occupants.  They may also be used to create vegetated, shaded areas from which cool, fresh air can be drawn into the building. 
  7. Energy generation: Building envelopes provide excellent opportunities to generate renewable energy for use in the building. This is done through photovoltaic and solar water heating panels and wind turbines. Ideally these are integrated in the design of the building envelope to improve the aesthetic quality of the building and minimise material requirements. 

A brief introduction to sustainable building envelopes can be accessed here.

Sustainable Food Environments

Food consumption patterns can have a significantly negative impact on the environment, as well as beneficial impacts on human health and well-being. For instance, locally grown food has much lower carbon emissions associated with it compared to imported, highly processed, foods. Similarly, a balanced and nutritious diet ensures health and wellbeing while a poor diet leads to increased susceptibility to ill-health and disease.

Achieving sustainability will, therefore, require food that both promotes health and has low negative environmental impacts (sustainable foods). Built environments can hinder, or support, access to these foods.

The Ecological Footprint measure can be used to define preferred, or more sustainable, food and diets. This can be used to propose ‘measures to promote sustainable diets’ such as:
  • Neighbourhoods should include a retailer of, or access to, fresh vegetables, fruit, beans and pulses, bakery products and milk, cheese and eggs.  The cost of these products should be affordable for the local population. 
  • Highly processed, non-local food products, oil, tea, coffee, beers, juice and wine, meat and fish should be more difficult to access than locally grown fresh fruit and vegetables. 
  • A proportion of household gardens and open space within the neighbourhood should be allocated to vegetable and fruit production. 
  • Restaurants with menus based on locally produced fruit, vegetables and include vegetarian, dairy and egg-based dishes, should be given preference over restaurants which have menus based on high ecological footprint items such as meat and imported items.  
Further analysis can be used determine built environment configurations and characteristics that promote access to sustainable foods and to develop ‘sustainable food environment criteria’ which can be used to assess built environments.

Further detail on this study, and the sustainable food environment criteria, can be accessed here.