Solar Energy Perspectives - IEA

Chapter 4: Buildings
Figure 4.3 Building sector energy consumption by fuel and by scenario
Solar
Biomass and waste
Heat
Electricity
Natural gas
Oil
Coal
Mtoe
5 000
4 500
4 000
3 500
3 000
2 500
2 000
1 500
1 000
500
0
2007
2030
Baseline
2030
BLUE Map
2050
Baseline
2050
BLUE Map
Note: Heat here represents only commercial heat, in district heating.
Source: IEA, 2010a.
Key point
Direct fuel use in building is considerably reduced in the BLUE Map Scenario.
The largest energy savings by end use in the BLUE Map Scenario in the residential sector
come from space heating. In the service sector, the largest savings come from lighting and
miscellaneous energy use. Highly energy efficient buildings have very low heat losses both
through the building envelope thanks to insulation and improved windows, and through air
exchange thanks to heat recovery systems. Current building regulations ensure that new
buildings are more efficient than existing ones, but much greater energy efficiency
improvements are feasible with “passive” solar concepts (Figure 4.4).
Passive solar buildings also maximise the free inputs of solar energy as heat during cold
seasons, and protect the building’s interior from too much sunshine in the warm seasons,
while allowing enough daylight to reduce the need for electric lighting (see Box: Day
lighting). Letting the sun heat buildings in winter and letting daylight enter them to displace
electric lighting is the least-cost form of solar energy. In some cases passive solar design can
help cut up to 50% of heating and cooling loads in new buildings. The necessary additional
investment costs are low when the products are mass-manufactured, and are largely
compensated for by the reduction in capacity of the heating/cooling system they allow – not
to mention the energy bill reductions for decades to come.
Buildings should also be thermally massive (i.e. with greater capacity to absorb and retain
heat) to avoid overheating in summer and oriented preferably toward the Equator. The glazing
should be concentrated on the equatorial side, as should the main living rooms. Passive
cooling techniques are based on the use of heat and solar protection techniques, heat storage
in thermal mass, and heat dissipation techniques. However, excess thermal mass could lead
to under-heating in winter, and should be avoided.
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© OECD/IEA, 2011