more than 50 per cent. The household-appliance share of energy consumption in residential homes vary from 21 per cent in China in 2000, to 25 per cent in the EU in 2004 and 27 per cent in the USA in 2005 (von Weizsäcker et al. 2009).
Managing energy supply and demand Energy use and emission patterns are affected by a building’s environmental performance and its energy load (on the demand side) or by the extent of its use of green sources of energy (on the supply side). Recent developments in design and technology offer significant potential to change the way energy demand and supply is managed in buildings.
On the demand side, there is growing evidence that energy consumption can be reduced by modifying the specification of technologies, appliances and fittings within buildings – in addition to designing the built form in a more sustainable way. Leading Information & Communication Technology (ICT) Infrastructure firms produce software for command centres, which can actively help to reduce a building’s carbon footprint by monitoring and controlling all components of a building’s energy use, from heating/cooling demand, to lighting and printing.
But the pattern of energy use in buildings varies considerably among regions and countries according to geographical location, climate, consumption patterns and state of development and urbanisation (IPCC 2007). Space heating is a dominant component of energy use in Europe and northern China, while water heating is of great significance in Japan (WBCSD 2009). In these areas, effective means of controlling energy demand and emissions include the improvement of heat-recovery systems, optimising daylight penetration with shallower buildings, substituting incandescent lighting with more energy-efficient systems such as CFL and LED lamps and introducing solar shading to reduce overheating.3 In addition to these design solutions, smart metering, which provides utility customers with information in real-time about their domestic energy consumption, has also proved effective at reducing overall household electricity consumption, with a 5-10 per cent drop recorded in private households in Germany and the UK (Luhmann 2007). In contrast, buildings located in warmer regions do not usually require space heating and require less hot water. Energy needs in low- income rural communities are largely determined by cooking (70 per cent) and other household activities (15 per cent) (Nekhaev 2004). In these locations, the impact of energy use will be more radically affected by introducing greener and cleaner fuel sources and
3. For example, as part of the Serbian Energy Efficiency Programme (SEEP 1) (IDA Credit and IRBD loan), 28 schools and hospitals were refurbished in Belgrade in 2005-09 with average energy savings of 39 per cent.
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more efficient domestic appliances than by introducing green building technologies.
On the supply side, there has been a significant shift in some countries in favour of renewable energies with bio-fuel and solar heating technologies becoming competitive with conventional sources (European Renewable Energy Council 2008). Photovoltaic (PV) technology is still relatively expensive but with the increasing volume of installed capacity and improvements in production, prices are lowering steadily.4
District heating and cooling systems5 that link
buildings are also proving effective at reducing energy costs, notably in Iceland, where 94 per cent of heat demand is now provided by these technologies (Euro Heat & Power 2009).
Retrofitting and new construction In developed countries, opportunities for greening the building sector are found mainly in retrofitting existing buildings to render them more environmentally efficient by reducing energy demand and using renewable energy sources. The urbanised regions of northern Europe and North America are no longer increasing their building stock rapidly. In the UK, for example, 75 per cent of the existing building stock is expected to be in use in 2050. In such circumstances, retrofitting existing buildings becomes a critical area of intervention to reduce energy demands and thus GHG emissions (Ravetz 2008).
For the majority of non-OECD countries, which have a significant housing deficit, the greatest potential to reduce energy demand will come from new generations of buildings with more efficient design performance standards (WBCSD 2007a). It follows that the major environmental and business case for the OECD residential and commercial sector will depend on retrofitting existing buildings, while non-OECD countries will have to invest heavily in new forms of sustainable design that goes beyond the performance of individual buildings (as discussed in the Cities chapter). Nonetheless, there are significant opportunities for retrofitting buildings in some of the bigger cities of the developing world by adopting energy efficiency design measures such as solar technology, clean water supplies and reducing
4. Grid parity, where the electricity produced by PV panels is available at the same cost level as electricity provision from the grid, is predicted to be achievable by 2013-14 based on data from Germany (Bhandari and Stadler 2009).
5. District heating and cooling describes systems distributing heat and/or cold generated in a centralised location for heating and combined heat and power respectively. District heating serves both, space and domestic water heating. Moreover, commercial and industrial as well as public buildings can be supplied with process heat. The heat often comes from combined heat and power plants (CHP) and therefore has the ability to achieve higher efficiencies and lower emissions than a separate heat and power production. Historically, district heating stations are dependent on fossil fuels but in the last years renewable sources were introduced.