Editing IPCC:AR6/SR15/Chapter-4 (section)

==== 4.3.3.2 Urban infrastructure, buildings and appliances ====

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Buildings are responsible for 32% of global energy consumption (IEA, 2016c) <sup>[[#fn:r304|304]]</sup> and have a large energy saving potential with available and demonstrated technologies such as energy efficiency improvements in technical installations and in thermal insulation (Toleikyte et al., 2018) <sup>[[#fn:r305|305]]</sup> and energy sufficiency (Thomas et al., 2017) <sup>[[#fn:r306|306]]</sup> . Kuramochi et al. (2018) <sup>[[#fn:r307|307]]</sup> show that 1.5°C-consistent pathways require building emissions to be reduced by 80–90% by 2050, new construction to be fossil-free and near-zero energy by 2020, and an increased rate of energy refurbishment of existing buildings to 5% per annum in OECD (Organisation for Economic Co-operation and Development) countries (see also Section 4.2.1).

Based on the IEA-ETP (IEA, 2017g) <sup>[[#fn:r308|308]]</sup> , Chapter 2 identifies large saving potential in heating and cooling through improved building design, efficient equipment, lighting and appliances. Several examples of net zero energy in buildings are now available (Wells et al., 2018) <sup>[[#fn:r309|309]]</sup> . In existing buildings, refurbishment enables energy saving (Semprini et al., 2017; Brambilla et al., 2018; D’Agostino and Parker, 2018; Sun et al., 2018) <sup>[[#fn:r310|310]]</sup> and cost savings (Toleikyte et al., 2018; Zangheri et al., 2018) <sup>[[#fn:r311|311]]</sup> .

Reducing the energy embodied in building materials provides further energy and GHG savings (Cabeza et al., 2013; Oliver and Morecroft, 2014; Koezjakov et al., 2018) <sup>[[#fn:r312|312]]</sup> , in particular through increased use of bio-based materials (Lupíšek et al., 2015) <sup>[[#fn:r313|313]]</sup> and wood construction (Ramage et al., 2017) <sup>[[#fn:r314|314]]</sup> . The United Nations Environment Programme (UNEP3) <sup>[[#fn:3|3]]</sup> estimates that improving embodied energy, thermal performance, and direct energy use of buildings can reduce emissions by 1.9 GtCO <sub>2</sub> e yr <sup>−1</sup> (UNEP, 2017b) <sup>[[#fn:r315|315]]</sup> '','' with an additional reduction of 3 GtCO <sub>2</sub> e yr <sup>−1</sup> through energy efficient appliances and lighting (UNEP, 2017b) <sup>[[#fn:r316|316]]</sup> ''.'' Further increasing the energy efficiency of appliances and lighting, heating and cooling offers the potential for further savings (Parikh and Parikh, 2016; Garg et al., 2017) <sup>[[#fn:r317|317]]</sup> .

Smart technology, drawing on the internet of things (IoT) and building information modelling, offers opportunities to accelerate energy efficiency in buildings and cities (Moreno-Cruz and Keith, 2013; Hoy, 2016) <sup>[[#fn:r318|318]]</sup> (see also Section 4.4.4). Some cities in developing countries are drawing on these technologies to adopt ‘leapfrog’ infrastructure, buildings and appliances to pursue low-carbon development (Newman et al., 2017; Teferi and Newman, 2017) <sup>[[#fn:r319|319]]</sup> (Cross-Chapter Box 13 in Chapter 5).

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