Energy use in cities (Climate Change and Urban Energy Systems)

Cities play a central role in driving global energy demand, but historically there has been relatively little information published on energy use in individual cities or urban areas. The OECD (1995) was one of the first organizations to estimate total urban energy demand around the world (74 percent), although the methodology supporting this estimate is unclear. More recently, the focus of aggregate urban-scale analysis has shifted to the level of greenhouse gas emissions attributable to cities, based largely on calculations of energy use in these cities.

In most cities around the world, data on local energy consumption or supply levels either have not been compiled or provide only a partial picture of the local situation. In the case of the latter, this is partly a function of the underlying goals of some of this research – it may be a residential sector-focused analysis, for instance – but it also reflects the many challenges inherent in obtaining these data. These include difficulties accessing proprietary market data held by the private companies serving a city and definitional questions related to what actually constitutes energy use resulting from activity in a city. Analyses may also focus narrowly on marketed fuels and technical energy, while fuels such as biomass and charcoal and non-technical sources (such as draft animals or other non-motorized transport modes in general) may be under-documented despite representing a large share of total local energy use.

There is also the issue of whether the urban system is defined as a spatial territory or functional unit and whether cities must account for all primary and/or embodied energy consumed within their borders (Parshall et al., 2010; Kennedy et al., 2009a). The notion that cities are ascribed responsibility for this use is considered problematic by some, arguing that such views diminish the energy efficiency benefits offered by urban lifestyles, given smaller dwelling sizes, reduced travel distances, increased access to public transportation, etc. (Satterthwaite, 2008; Dodman, 2009). The notion of holding a city accountable for local energy use can also be seen as problematic, as it is the behavior of individuals or institutions in cities that is at the root of this level of energy usage, rather than the city itself.

This argument speaks to the fact that analyses of urban energy usage are helpful primarily because of the spotlight they shine on the need for energy and climate policies that respect the unique attributes of urban areas. City-specific analyses focus even more directly on this point, using local energy supply and use data to inform local energy efficiency strategies or climate change mitigation or adaptation plans. In some cases, cross-city comparisons are employed because they provoke questions among local policymakers about how they can attain energy use or emission levels comparable to those in other cities. Per capita electricity use is a metric commonly employed to highlight such comparisons between cities (see Figure 4.2), although such comparisons are most useful if they account for differences in climate or level of economic development.

Managing CO2 emissions from buildings: Lessons from the UK, USA, and India

This synopsis is based on the research paper commissioned by the World Bank and presented in the 5th Urban Research Symposium on Cities and Climate Change held at Marseille in June 2009.

In 2002, buildings were responsible for 7.85 Gt, or 33 percent of all energy-related CO2 emissions worldwide and these emissions are expected to grow to 11 Gt (B2 scenario) or 15.6 Gt (A1B scenario) by 2030 (IPCC, 2007). However, as the housing market in the UK, USA, and several other developed countries has gone into deep and prolonged recession, the opportunity for very substantial investment into improving the existing building stock has opened up. In fact according to the Fourth Assessment Report (AR4) of the IPCC (2007), approximately 29 percent of CO2 emissions can be saved economically, or at a net benefit to society, even at zero carbon price. Mitigation measures in the residential and commercial sectors can save approximately 1.6 billion and 1.4 billion tons of CO2 emissions, respectively, by 2020 (Urge-Vorsatz et al., 2007). While the magnitude of these large potentials that can be captured has been known for decades, many of these energy efficiency possibilities have not been realized. This is because of certain characteristics of markets, user behavior, and a lack of critical evaluation of the available tools and models that could be used by planners, building designers, and policymakers to measure, benchmark, target, plan, and monitor energy-related CO2 emissions and forecast reductions from existing buildings. This research paper therefore comparatively evaluates the building-related CO2 measurement, benchmarking, and reduction approaches available in the USA, UK, and India, to share the lessons learnt in implementing CO2 reducing policies in each of these countries, by:

• Establishing what tools, approaches, and methodologies are available for measuring energy use and CO2 emissions from existing buildings in the UK, USA, and India.

• Reviewing and comparing benchmarks of annual energy consumption (kWh/m2 per year) and CO2 emissions (kgCO2/m2 per year) from buildings-in-use in the case study countries.

• Developing more rigorous standards for existing buildings (to reduce their energy consumption), which could be adopted by developed and rapidly developing cities taking account of building type, local climate and occupancy.

• Evaluating various strategies and measures available for maximising CO2 emission reductions in existing buildings (above 80 percent in developed countries) through improved energy efficiency, low and zero carbon technologies, as well as non-technical solutions (education and awareness, behavioral change), and to identify barriers for their implementation.

• Finally, recommending policy measures that would increase uptake of the selected CO2 reduction strategies in existing buildings.

A comparative analysis is undertaken to evaluate the strengths and weakness of methods such as BREEAM/CSH in the UK, LEED in the USA, and TERI-GRIHA and LEED-India in India. Robust performance-based standards (in terms of kWh/m2 per year or kgCO2/m2 per year) are recommended for reducing the energy consumption of existing buildings present in both developed and rapidly urbanising cities. A range of policy instruments and measures are suggested to remove or lower barriers and encourage uptake of various CO2 reduction strategies in existing buildings. Among these are: appliance standards, building energy codes, appliance and building labelling, pricing measures and financial incentives, utility demand-side management programs, and public sector energy leadership programs including procurement policies. Because culture and occupant behavior are major determinants of energy use in buildings, these policy approaches need to go hand in hand with programs that increase consumer access to information, awareness, and knowledge. At present, however, there is particularly a lack of accurate information about exactly how much variation occupant behavior introduces to a building’s energy consumption.

It is realized that the UK is world-leading in its CO2 reduction policy for buildings but lacks good-quality bottom-up data sets of real energy consumption and CO2 emissions in buildings. The USA on the other hand has excellent data sets by EIA and DoE, but needs to have national-level policies and targets for CO2 reduction from buildings. India is working on both policy and data collection given that the energy data are quite polarized between the urban and rural. In fact the Bureau of Energy Efficiency is working with USAID’s ECO-III program to benchmark a range of commercial and institutional buildings -although the focus is primarily on energy efficiency and not CO2 reduction. Hopefully, robust targets for CO2 reduction and policies to achieve those targets will be set soon.

The role of data and analysis is particularly emphasized, since the building sector is not considered as an independent sector and there is a lack of consistent data, which makes it difficult to understand the underlying changes that affect energy consumption in this sector. It is essential to make available comprehensive building energy information to allow suitable analysis and efficiently plan energy policies for the future. In fact, regularization of data collection and analysis for the building sector can help quantify technology performance, its cost-effectiveness, role of barriers, identification of beneficiaries, and targeting of government and industry policies, programs, and measures. In that respect, studies developed by the EIA on the energy consumption of residential and commercial buildings in the USA are a valuable reference (EIA, 2001, 2003, 2006, 2008a, b).

It is hoped that findings from this project will help to expedite the process of achieving significant reductions in energy use and CO2 emissions from the existing building stock by formulating policies that address the conventional barriers to implementation and increase the uptake of low carbon systems (heat pumps, solar hot water, solar PV, micro-combined heat and power, micro-wind) in buildings and cities. There is a need for adaptive policies to be mainstreamed through all  development and environmental policies such as retrofitting existing building stock to ensure that it remains resilient to climate change impacts. On the longer term, the data archive of this study will be of immense value to all those with a stake in a low-carbon future, be it policy, practice or academic understanding. No doubt the ultimate aim is to make the global building stock become low-energy, low-carbon and more resilient to climate change effects.

Tracking urban energy consumption

Despite these challenges, there are several studies that have sought to examine urban energy consumption at different scales.

In 2008, the International Energy Agency (IEA) calculated global urban energy use, concluding that 67 percent of global primary energy demand – or 7,903 Mtoe – is associated with urban areas (IEA, 2008; see Table 4.2). By 2030, urban energy consumption is expected to increase to 12,374 Mtoe, representing 73 percent of global primary energy demand and reflecting dramatic anticipated growth in urban population levels around the world.

Figure 4.2: Per capita electricity consumption in MWh/capta.

Regional or country specific analyses have also focused on aggregate urban scale energy consumption. Dhakal (2009) estimated that the urban share of total commercial energy use in China is 84 percent, while in the USA, urban areas are responsible for between 37 and 86 percent of national direct fuel consumption in residential, commercial, and industrial buildings, and between 37 and 77 percent of national on-road gasoline and diesel consumption (Parshall et al., 2010).3 Such studies frequently contrast energy use in urban and non-urban areas of a country. For example, a Brookings Institution study showed that large metropolitan areas in the USA have smaller per-capita energy consumption and carbon emissions compared with the national average (Brown et al., 2008). By contrast, Dhakal (2009) found dramatically higher rates of energy use in Chinese cities compared to rural areas.

Other studies focus narrowly on detailing the fuel mix in specific cities. ICLEI (2009b) compiled energy use data in 54 South Asian cities, identifying the absolute quantities of each fuel type broken out by sector (see Table 4.3). Kennedy et al. (2009a, 2009b) compared energy use and emissions data in ten cities in Africa, Asia, Europe, and North America, while other individual local authority analyses have been published as part of each city’s sustainability or climate initiatives or as part of ongoing public reporting efforts on different key performance indicators (for example, see Mairie de Paris 2007; Shanghai Municipal Statistics Bureau, 2008).

There is information that is less commonly available that is helpful when crafting city-specific mitigation and adaptation policies. New York City’s sustainability plan breaks out building-related energy use by function and sector; that is, how much energy is expended on lighting versus heating, cooling, and other types of specific energy demand in different types of buildings (see Table 4.4). This information is useful because it can help a local authority prioritize its scarce time and financial resources when implementing a sustainability plan. Diurnal information, or a further breakdown of how energy is used by different applications (e.g., heating, lighting, etc.) over the course of the day, can also be helpful in highlighting opportunities to employ different types of energy efficient technology within a building or on a citywide scale (Parshall, 2010).

Table 4.2: World energy demand in cities by fuel.