Chapitre 2 • A4:Mise en page 1
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> 2 Baseline income rural areas of Africa, India and China the main energy source for more than 70% of the population is traditional biomass such as wood, animal dung and crop waste (Figures 2.5 and 2.6). In addition, kerosene and paraffin are still widely used for lighting in the rural areas of developing countries. By using wood biomass these practices contribute to deforestation and desertification processes, decreasing the capacity of existing carbon sinks to absorb CO2 from the atmosphere. Today, around 2.4 billion people depend on biomass – wood, agricultural residues and dung – for cooking and heating. That number is expected to increase to 2.6 billion by 2030. According to a forecast presented by the IEA (2002), in 2030 biomass use will still represent over half of residential energy consumption in developing countries. The change of this trend largely depends on efforts to alleviate rural poverty and improve the living conditions of these populations (Figure 2.7). This chapter describes the overall use of energy by the building sector. After analyzing how energy is consumed over the building’s life cycle, it explores how energy consumption is distributed among different building sectors and types. Attention is primarily given to the operational phase of the building, and the shares of energy consumed for heating, cooling, lighting and other appliances in different countries and by different types of buildings. These analyses are complemented with practical examples, which illustrate energy sources in different building phases and sectors, as well as the effects of climate, building type and building technology.
EVERY YEAR, THE WORLD consumes around 7,500 Mtoe (million tons of oil equivalent) of en-ergy (Figure 2.1). In 2003, three countries – China, Russia and the United States – were the leading producers and consumers of world energy. Altogether, these three countries produced 39% and consumed 41% of the world's total energy supply (IEA 2002, 2005; EIA 2005). While primary energy consumption will grow by almost 50% from 2005 to 2030 (Figure 2.2), the shares of different energy sources are not expected to change significantly in the near future. This means that, in the near future, more fossil fuels will be used to meet energy demands, increasing the greenhouse gas emissions further. The building sector is responsible for a large share of the world’s total energy consumption. The International Energy Agency (IEA 2005) estimates that buildings account for 30-40% of the worldwide energy use, which is equivalent to 2,500 Mtoe every year. Accordingly, studies carried out by the OECD suggest that residential and commercial building sectors are responsible for about 30% of primary energy consumed in OECD countries, and for approximately 30% of the greenhouse gas emissions of these countries (OECD 2002b, 2003). These studies also indicate that energy consumption by the building sector in OECD countries has continually increased since the 1960s and will continue to do so in the coming years. In non-OECD countries the situation is also worrying. On one hand, many middle-income countries rely on fossil fuels to meet the energy demand in their building stocks. On the other hand, in the low-
Coal Oil Natural gas
(Mtoe)
Nuclear Hydro Renewable Energy etc
18000 16000
4% 2%
14000 4% 3%
12000
3% 3%
10000 3% 3%
8000
4000 Fig. 2.1 Outlook for world energy supply / demand by fuel.
4
2% 2%
1% 18% 49%
2000
6% 28%
7%
27%
25%
7% 23%
6000
5%
38%
39% 26%
294%
38%
38%
24%
24%
29%
0 1971
2000
2010
2020
2030
Source : IEA/World Energy Outlook 2002 (Agency for Natural Resources and Energy, Government of Japan 2006).