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

=== Box 9.3 | Emerging Energy Demand Trends in Residential Buildings ===

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Literature assessed points to three major energy demand trends:

'''Cooling energy demand'''

In a warming world ( [[#IPCC--2021|IPCC 2021]] ) with a growing population and expanding middle-class, the demand for cooling is likely to increase leading to increased emissions if cooling solutions implemented are carbon intensive ( [[#Santamouris--2016|Santamouris 2016]] ; [[#Sustainable%20Energy%20for%20All--2018|Sustainable Energy for All 2018]] ; [[#Dreyfus--2020b|Dreyfus et al. 2020b]] ; [[#Kian%20Jon--2021|Kian Jon et al. 2021]] ; [[#UNEP%20and%20IEA--2020|UNEP and IEA 2020]] ). Sufficiency measures such as building design and forms, which allow balancing the size of openings, the volume, the wall and window area, the thermal properties, shading, and orientation are all non-cost solutions, which should be considered first to reduce cooling demand. Air conditioning systems using halocarbons are the most common solutions used to cool buildings. Up to 4 billion cooling appliances are already installed and this could increase to up to 14 billion by 2050 ( [[#Peters--2018|Peters 2018]] ; [[#Dreyfus--2020b|Dreyfus et al. 2020b]] ). Energy efficiency of air conditioning systems is of a paramount importance to ensuring that the increased demand for cooling will be satisfied without contributing to global warming through halocarbon emissions ( [[#Campbell--2018|Campbell 2018]] ; [[#Shah--2015|Shah et al. 2015]] , 2019; [[#UNEP%20and%20IEA--2020|UNEP and IEA 2020]] ). The installation of highly efficient technological solutions with low global warming potential (GWP), as part of the implementation of the Kigali amendment to the Montreal Protocol, is the second step towards reducing GHG emissions from cooling. Developing renewable energy solutions integrated to buildings is another track to follow to reduce GHG emissions from cooling.

'''Electricity energy demand'''

Building electricity demand was slightly above 43 EJ in 2019, which is equivalent to more than 18% of global electricity demand. Over the period 1990–2019, electricity demand increased by 161%. The increase of global electricity demand is driven by the combination of rising incomes, income distribution and the S-curve of ownership rates ( [[#Wolfram--2012|Wolfram et al. 2012]] ; [[#Gertler--2016|Gertler et al. 2016]] ). Electricity is used in buildings for plug-in appliances, in other words, refrigerators, cleaning appliances, connected and small appliances and lighting. An important emerging trend in electricity demand is the use of electricity for thermal energy services (cooking, water and space heating). The increased penetration of heat pumps is the main driver of the use of electricity for heating. Heat pumps used either individually or in conjunction with heat networks can provide heating in cold days and cooling in hot ones. ( [[#Lowes--2020|Lowes et al. 2020]] ) suggests electricity is expected to become an important energy vector to decarbonise heating. However, the use of heat pumps will increase halocarbon emissions ( [[#UNEP%20and%20IEA--2020|UNEP and IEA 2020]] ). [[#Connolly--2017|Connolly (2017)]] , [[#Bloess--2018|Bloess et al. (2018)]] , and [[#Barnes--2020|Barnes and Bhagavathy (2020)]] argue for electrification of heat as a cost-effective decarbonisation measure, if electricity is supplied by renewable energy sources ( [[#Ruhnau--2020|Ruhnau et al. 2020]] ). The electrification of the heat supplied to buildings is likely to lead to an additional electricity demand and consequently additional investment in new power plants. [[#Thomaßen--2021|Thomaßen et al. (2021)]] identifies flexibility as a key enabler of larger heat electrification shares. Importantly, heat pumps work at their highest efficiency level in highly efficient buildings and their market uptake is likely to require incentives due to their high up-front cost ( [[#Hannon--2015|Hannon 2015]] ; [[#Heinen--2017|Heinen et al. 2017]] ).

'''Digitalisation energy demand'''

Energy demand from digitalisation occurs in data centres, which are dedicated buildings or part of buildings for accommodating large amount of information technologies equipment such as servers, data storage and communication devices, and network devices. Data centres are responsible for about 2% of global electricity consumption ( [[#Avgerinou--2017|Avgerinou et al. 2017]] ; [[#Diguet--2019|Diguet and Lopez 2019]] ). Energy demand from data centres arises from the densely packed configuration of information technologies, which is up to 100 times higher than a standard office accommodation ( [[#Chu--2019|Chu and Wang 2019]] ). Chillers combined with air handling units are usually used to provide cooling in data centres. Given the high cooling demand of data centres, some additional cooling strategies, such as free cooling, liquid cooling, low-grade waste heat recovery, absorption cooling and so on, have been adopted. In addition, heat recovery can

Box 9.3

provide useful heat for industrial and building applications. More recently, data centres are being investigated as a potential resource for demand response and load balancing ( [[#Zheng--2020|Zheng et al. 2020]] ; [[#Koronen--2020|Koronen et al. 2020]] ). Supplying data centres with renewable energy sources is increasing ( [[#Cook--2014|Cook et al. 2014]] ) and is expected to continue to increase ( [[#Koomey--2011|Koomey et al. 2011]] ). Estimates of energy demand from digitalisation (connected and small appliances, data centres, and data networks) combined vary from 5% to 12% of global electricity use ( [[#Gelenbe--2015|Gelenbe and Caseau 2015]] ; [[#Malmodin--2018|Malmodin and Lundén 2018]] ; [[#Ferreboeuf--2019|Ferreboeuf 2019]] ; [[#Diguet--2019|Diguet and Lopez 2019]] ). According to ( [[#Ferreboeuf--2019|Ferreboeuf 2019]] ) the annual increase of energy demand from digitalisation could be limited to 1.5% against the current 4% if sufficiency measures are adopted along the value chain.

Digitalisation occurs also at the construction stage. ( [[#European%20Union--2019|European Union 2019]] ; [[#Witthoeft--2017|Witthoeft and Kosta 2017]] ) identified seven digital technologies already in use in the building sector. These technologies include (i) Building Information Modelling/Management (BIM), (ii) additive manufacturing, also known as 3D printing, (iii) robots, (iv) drones, (v) 3D scanning, (vi) sensors, and (vii) internet of things (IoT). BIM supports decision making in the early design stage and allows assessing a variety of design options and their embodied emissions ( [[#Basbagill--2013|Basbagill et al. 2013]] ; [[#Röck--2018|Röck et al. 2018]] ). 3D printing reduces material waste and the duration of the construction phase as well as labour accidents ( [[#Dixit--2019|Dixit 2019]] ). Coupling 3D printing and robots allows for increasing productivity through fully automated prefabricated buildings. Drones allow for a better monitoring and inspection of construction projects through real-time comparison between planned and implemented solutions. Coupling drones with 3D scanning allows predicting building heights and energy consumption ( [[#Streltsov--2020|Streltsov et al. 2020]] ). Sensors offer a continuous data collection and monitoring of end-use services (i.e., heating, cooling, and lighting), thus allowing for preventive maintenance while providing more comfort to end-users. Coupling sensors with IoT, which connects to the internet household appliances and devices such as thermostats, enable demand-response, and flexibility to reduce peak loads ( [[#IEA--2017a|IEA 2017a]] ; [[#Lyons--2019|Lyons 2019]] ). Overall, connected appliances offer a variety of opportunities for end-users to optimise their energy demand by improving the responsiveness of energy services ( [[#IEA--2017a|IEA 2017a]] ; [[#Nakicenovic--2019|Nakicenovic et al. 2019]] ) through the use of digital goods and services ( [[#Wilson--2020|Wilson et al., 2020]] ) including peer-to-peer electricity trading ( [[#Morstyn--2018|Morstyn et al. 2018]] ).

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