Energy Use in Cities
The world is facing a crisis in regards to getting a handle on, and reducing, our carbon emissions. On the off chance that you don’t believe in climate change (although this would not be the best opinion to express on one of my posts), then you should instead be motivated by peak oil, the loss of fossil fuels and the future of national energy security, for whatever country you happen to live in. One way or another, our energy use needs to reduce.
Of course most single individuals can’t begin to get their heads around the nature of the actual problem. Sure, there are plenty of calculators that let you understand your own energy use, and that’s important. But there are other forms of energy use brought about by the way we live, work, and play that are not going to be addressed by single individuals. Energy creation, distribution, and use is as much a national problem as an individual one.
Of course a nation uses energy in many different ways. And in respect to this blog, and my own particular interests, the shape of a place, or the way a place is designed has a significant impact on its energy use. Cities use energy differently from other built forms. If we are to design with energy efficiency in mind, it is important to understand what physical factors lead to increased or decreased energy use.
Since 1993, the International Energy Agency (IEA) has provided medium to long-term projections about global energy use using a World Energy Model (WEM). The IEA uses the WEM to produce an annual World Energy Outlook which uses a scenario approach to examine future trends in energy with a projection period to 2030 (OECD/IEA, 2010a). In 2008, the World Energy Outlook devoted an entire chapter to ‘Energy use in cities’ as they project that by 2030, due to growing urban populations, urban energy use will account for nearly three quarters of total energy use worldwide. They also recognize that factors that influence city energy use are different from the energy uses of the countries the cities are in as a whole (OECD/IEA, 2008).
Understanding energy use in cities is complex. Indicative data suggests that in 2006, about two-thirds of the world’s energy was consumed in cities, accounting for over 70% of global GHG emissions, even though only around half of the world’s population lived in urban areas. City residents consume more coal, gas, and electricity than the global average, but less oil. However, these global totals do not clearly express what is happening in cities country by country. In industrialized countries, the energy use per capita of city residents is slightly lower than the national average, for example, in the United States, most of the European Union, Australia, and New Zealand. By contrast, residents in China use almost twice as much energy per capita as the national average due to higher average incomes and better access to modern energy services (OECD/IEA, 2008). In industrialized countries where most citizens have a high standard of living, city energy consumption per capita is typically less than the national average. In developing countries where citizens may have a lower standard of living, cities represent technological development and residents of cities in developing countries tend to have higher per capita energy consumption than the national average.
To provide their populations with the myriad of services demanded, cities need large amounts of energy which is predominantly fossil fuel based. Globally, the natural gas and electricity consumed in cities is higher than the average of all fuels, and much higher than the share of the world’s population living in cities. This is due to the more extensive infrastructure in cities for energy distribution and higher appliance ownership rates in developing cities relative to rural areas. The oil consumed in cities is smaller than the average of all fuels due to higher penetration of electricity for heating and cooking and wider use of urban public transport networks (OECD/IEA, 2008).
It is not easy to isolate emissions for cities due to the fact that some emissions are generated outside of the metropolitan region for goods or services used within the city and vice versa. There is irregularity in the accounting of Scope 3 emissions (Kennedy et al., 2009). Some studies show that if Scope 3 emissions were to be included, the energy use attributed to cities could be as much as double, but these are very difficult to quantify as many Scope 3 emissions can not solely be attributed to a single city alone.
The World Bank has been working on a standardized system of accounting for city GHG emissions and has been collecting and assembling data that has been peer reviewed and is considered comparable (The World Bank, 2010). This work shows that there are clear and often substantial differences when considering national GHG per capita emissions compared to corresponding cities:
|Country/City||GHG Emissions (tCO2e/capita)||Year|
|Rio de Janeiro||2.1||1998|
|Toronto Met. Area||11.6||2005|
|Greater London Area||9.6||2003|
|New York City||10.5||2005|
In general you can see from the above table a clear (peer reviewed, certified) comparison of city emissions compared to the national average which proves the above but also leads to some other very interesting conclusions.
Firstly, in the case of American cities, it is clear that urban living (even the worst offenders) still puts the per capita emissions below the national average. What’s interesting about this is that no one is doing a similar study for all the suburban or rural areas of the country. If the city numbers are included in the national average, that means that the areas that are ‘not city’ are actually much worse than the national average, exacerbating the nature of the problem and making the performance of the cities even better.
Second, with all of this ‘good news’ about energy use in cities, why does the IEA say that 2/3 of the world’s energy was consumed in cities for only half the population? Because this shows the staggering impact of the urbanization of developing countries. The population numbers in these countries far surpasses those in already industrialized nations. So while for the developed world, urbanization is a way to reduce our already high energy consumption, in the developing world, this explosion of urbanization has a frighteningly detrimental impact on energy consumption.
Third, before anyone get too excited about the numbers, it’s important to remember what we should be aiming for by way of emissions per capita if we are to arrest man’s impact on the climate. According to David MacKay, in the UK for example, we should be getting that number down to 1 ton per person per year (MacKay, 2009). Of course the cleaner to energy, the lower the emissions- so it’s partly about reduction and partly about production. But either way, don’t let small gains fool you as to the true scale and nature of the problem we face, and the level of change that will be needed to overcome it.
So what can be learned from this? I suppose it entirely depends on the focus of your interest. For existing cities and urban environments in developed nations, looking at factors influencing reduction of energy use in cities can show a way for us to improve our national consumption. For those interested in developing countries, it is critical to work into the development of places now, at this stage, ways to try to reduce energy use as much as possible to try and pull back the impact.
As an interesting addition to this article, Lloyd Alter over at Treehugger recently put together a well documented article on the significance of location/urban design on energy use citing many current studies that are out there which helps illustrate part of the reason for energy use reduction in urban areas of developed countries. It’s well worth a look if you are interested in the subject.