Editing IPCC:AR6/WGIII/Chapter-9 (section)

=== 9.7.2 Links Between Mitigation and Adaptation in Buildings ===

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Adaptation options interacts with mitigation efforts because measures to cope with climate change impacts can increase energy and material consumption, which may lead to higher GHG emissions ( [[#Kalvelage--2014|Kalvelage et al. 2014]] ; [[#Davide--2019|Davide et al. 2019]] ; [[#Sharifi--2020|Sharifi 2020]] ). Energy consumption is required to adapt to climate change. Mitigation measures, in turn, influence the degree of vulnerability of buildings to future climate and, thus, the adaptation required.

Studies have assessed the increases in energy demand to meet indoor thermal comfort under future climate ( [[#de%20Wilde--2012|de Wilde and Coley 2012]] ; [[#Li--2012|Li et al. 2012]] ; [[#Clarke--2018|Clarke et al. 2018]] ; [[#Andrić--2019|Andrić et al. 2019]] ). Higher cooling needs may induce increases in energy demand ( [[#Wan--2012|Wan et al. 2012]] ; [[#Li--2012|Li et al. 2012]] ), which could lead to higher emissions, when electricity is fossil-based (International Energy Agency 2018; [[#Biardeau--2020|Biardeau et al. 2020]] ), and generate higher loads and stress on power systems ( [[#Dirks--2015|Dirks et al. 2015]] ; [[#Auffhammer--2017|Auffhammer et al. 2017]] ). In this regard, increasing energy efficiency of space cooling appliances and adopting dynamic cooling setpoint temperatures, can reduce the energy needs for cooling and limit additional emissions and pressures on power systems ( [[#Davide--2019|Davide et al. 2019]] ; [[#Bienvenido-Huertas--2020|Bienvenido-Huertas et al. 2020]] ; [[#Bezerra--2021|Bezerra et al. 2021]] ) ( [[#9.4|Section 9.4]] , Figure 9.11 and Supplementary Material Tables 9.SM.1 to 9.SM.3). This can also be achieved with on-site renewable energy production, especially solar PV for which there can be a timely correlation between power supply and cooling demand, improving load matching ( [[#Salom--2014|Salom et al. 2014]] ; [[#Grove-Smith--2018|Grove-Smith et al. 2018]] ).

Mitigation alternatives through passive approaches may increase resilience to climate change impacts on thermal comfort and reduce active cooling needs ( [[#Wan--2012|Wan et al. 2012]] ; [[#van%20Hooff--2016|van Hooff et al. 2016]] ; [[#Andrić--2019|Andrić et al. 2019]] ; [[#González%20Mahecha--2020|González Mahecha et al. 2020]] ; [[#Rosse%20Caldas--2020|Rosse Caldas et al. 2020]] ). Combining passive measures can help counteracting climate change driven increases in energy consumption for achieving thermal comfort ( [[#Huang--2016|Huang and Hwang 2016]] ).

Studies raise the concern that measures aimed at building envelope may increase the risk of overheating in a warming climate ( [[#Dodoo--2016|Dodoo and Gustavsson 2016]] ; [[#Fosas--2018|Fosas et al. 2018]] ) ( [[#9.4|Section 9.4]] ). If this is the case, there may be a conflict between mitigation through energy efficiency building regulations and climate change adaptation ( [[#Fosas--2018|Fosas et al. 2018]] ). However, while overheating may occur as a result of poor insulation design, better insulation may actually reduce overheating when properly projected and the overheating risk can be overcome by clever designs ( [[#Fosas--2018|Fosas et al. 2018]] ).

Strengthening building structures to increase resilience and reduce exposure to the risk of extreme events, such as draughts, torrential floods, hurricanes and storms, can be partially achieved by improving building standards and retrofitting existing buildings ( [[#Bjarnadottir--2011|Bjarnadottir et al. 2011]] ). However, future climate is not yet considered in parameters of existing building energy codes ( [[#Steenbergen--2012|Steenbergen et al. 2012]] ). While enhancing structural resilience would lead to GHG emissions ( [[#Liu--2018|Liu and Cui 2018]] ), so would disaster recovery and rebuilding. This adaptation-mitigation trade-off needs to be further assessed.

Since adaptation of the existing building stock may be more expensive and require building retrofit, climate change must be considered in the design of new buildings to ensure performance robustness in both current and future climates, which can have implications for construction costs ( [[#Hallegatte--2009|Hallegatte 2009]] ; [[#Pyke--2012|Pyke et al. 2012]] ; [[#de%20Wilde--2012|de Wilde and Coley 2012]] ; [[#de%20Rubeis--2020|de Rubeis et al. 2020]] ; [[#Picard--2020|Picard et al. 2020]] ) and emissions ( [[#Liu--2018|Liu and Cui 2018]] ). Building energy codes and regulations are usually based on cost-effectiveness and historical climate data, which can lead to the poor design of thermal comfort in future climate ( [[#Hallegatte--2009|Hallegatte 2009]] ; [[#Pyke--2012|Pyke et al. 2012]] ; [[#de%20Wilde--2012|de Wilde and Coley 2012]] ) and non-efficient active adaptive measures based on mechanical air conditioning ( [[#De%20Cian--2019|De Cian et al. 2019]] ) ( [[#9.4|Section 9.4]] , Figure 9.11 and Supplementary Material Tables 9.SM.1 to 9.SM.3). However, uncertainty about future climate change creates difficulties for projecting parameters for the design of new buildings ( [[#Hallegatte--2009|Hallegatte 2009]] ; [[#de%20Wilde--2012|de Wilde and Coley 2012]] ). This can be especially relevant for social housing programs ( [[#Rubio-Bellido--2017|Rubio-Bellido et al. 2017]] ; [[#Triana--2018|Triana et al. 2018]] ; [[#González%20Mahecha--2020|González Mahecha et al. 2020]] ) in developing countries.

The impacts on buildings can lead to higher maintenance needs and the consequent embodied environmental impacts related to materials production, transportation and end-of-life, which account for a relevant share of GHG emissions in buildings lifecycle ( [[#Rasmussen--2018|Rasmussen et al. 2018]] ). Climate change induced biodegradation is especially important for bio-based materials such as wood and bamboo ( [[#Brambilla--2020|Brambilla and Gasparri 2020]] ) which are important options for reducing emissions imbued in buildings’ construction materials ( [[#Peñaloza--2016|Peñaloza et al. 2016]] ; [[#Churkina--2020|Churkina et al. 2020]] ; [[#Rosse%20Caldas--2020|Rosse Caldas et al. 2020]] ).

Although there can potentially be conflicts between climate change mitigation and adaptation, these can be dealt with proper planning, actions, and policies. The challenge is to develop multifunctional solutions, technologies and materials that can mitigate GHG emissions while improving buildings adaptive capacity. Solutions and technologies should reduce not only buildings’ operational emissions, but also embodied emissions from manufacturing and processing of building materials ( [[#Röck--2020|Röck et al. 2020]] ). For instance, some building materials, such as bio-concrete, can reduce lifecycle emissions of buildings and bring benefits in terms of building thermal comfort in tropical and subtropical climates. Also, energy efficiency, sufficiency and on-site renewable energy production can help to increase building resilience to climate change impacts and reduce pressure on the energy system.

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