6 Residential and commercial buildings
Status of the sector and emission trends
In 2004, direct GHG emissions from the buildings sector (ex- cluding emissions from electricity use) were about 5 GtCO2-eq/yr (3 GtCO2-eq/yr CO2; 0.1 GtCO2-eq/yr N2O; 0.4 GtCO2-eq/yr CH4 and 1.5 GtCO2-eq/yr halocarbons). The last figure includes F-gases covered by the Montreal protocol and about 0.1–0.2 GtCO2-eq/yr of HFCs. As mitigation in this sector includes many measures aimed at saving electricity, the mitigation potential is generally calculated including electricity saving measures. For comparison, emission figures of the building sector are often presented including emissions from electricity use in the sector . When including the emissions from electricity use, energy-related CO2 emissions from the buildings sector were 8.6 Gt/yr, or 33% of the global total in 2004. Total GHG emissions, including the emissions from electricity use, are then estimated at 10.6 Gt CO2eq/yr (high agreement, medium evidence) [6.2].
Future carbon emissions from energy use in buildings
The literature for the buildings sector uses a mixture of baselines. Therefore, for this chapter, a building sector baseline was defined, somewhere between SRES B2 and A1B2, with 14.3 GtCO2-eq GHG emissions (including emissions from electricity use) in 2030. The corresponding emissions in the SRES B2 and A1B scenarios are 11.4 and 15.6 GtCO2. In the SRES B2 scenario (Figure TS.17), which is based on relatively lower economic growth, North America and Non-Annex I East Asia account for the largest portion of the increase in emissions. In the SRES A1B scenario, which shows rapid economic growth, all the CO2 emissions increase is in the developing world: Asia, Middle East and North Africa, Latin America, and Sub-Saharan Africa, in that order. Overall, average annual CO2 emission growth between 2004 and 2030 is 1.5% in Scenario B2 and 2.4% in Scenario A1B (high agreement, medium evidence) [6.2, 6.3].
Figure TS.17: CO2 emissions (GtCO2) from buildings including emissions from the use of electricity, 1971–2030 [Figure 6.2].
Note: Dark red – historic emissions; light red – projection according to SRES B2 scenario. EECCA=Countries of Eastern Europe, the Caucasus and Central Asia.