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Article

Exploring the Impacts of Lifestyle Changes in the Global Energy Transition: Insights from a Model-Based Analysis Using PROMETHEUS

by
Panagiotis Fragkos
*,
Eleftheria Zisarou
and
Andreas Andreou
E3Modelling S.A., Panormou 70-72, PO 11523 Athens, Greece
*
Author to whom correspondence should be addressed.
Climate 2024, 12(12), 193; https://doi.org/10.3390/cli12120193
Submission received: 11 October 2024 / Revised: 13 November 2024 / Accepted: 19 November 2024 / Published: 21 November 2024
(This article belongs to the Section Climate Adaptation and Mitigation)
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Abstract

:
A global clean energy transition is required for achieving ambitious climate goals and ensuring sustainable development. While technological advancements are crucial, they are not sufficient on their own to meet Paris Agreement (PA) climate targets. Integrating lifestyle changes, particularly in sectors such as transport and residential use of energy, into climate policies and energy modeling framework is gaining recognition in energy transition research. This study explores the impact of lifestyle changes on the global energy system and CO2 emissions using the PROMETHEUS model, an advanced energy–economy–environment system model. In this research we present scenarios in which lifestyle changes, such as reduced private car use and increased adoption of public transport and energy-savings behavior in households, are gradually introduced and complement technological and policy measures within the energy transition framework. We explore the impacts of scenarios with different levels of climate policies and lifestyle changes to evaluate the effects of various behavioral shifts on global energy consumption and CO2 emissions. Results show that even under current climate policies, lifestyle changes can reduce global energy demand by 5% by 2030 and 10% by 2050. When combined with ambitious decarbonization policies, the reductions are much more significant, leading to a 35% reduction by 2050 compared to the baseline scenario. Overall, the findings suggest that lifestyle changes, when effectively integrated with climate policy measures, can reduce energy demand and carbon emissions, alleviate the pressure on energy supply, and reduce the cost burden for energy producers and consumers.

1. Introduction

The global energy transition, based on the shift from fossil fuels to renewable energy sources, is essential to mitigate climate change, as discussed at the Climate Change Conference (COP28) [1]. This requires a comprehensive understanding on how energy systems can evolve to meet future energy demand while reducing greenhouse gas emissions. In this direction, countries and industries have focused on reducing carbon emissions with the deployment of renewable technologies [2], energy efficiency improvements [3] and policy interventions such as carbon pricing mechanism [4]; however, the recent literature suggests that technological advancements alone may not be sufficient to drive the necessary changes [5,6,7]. This has led to an increasing focus on the role of consumer behavior and lifestyle choices in shaping energy demand towards the success of the energy transition efforts.
These factors have started to gain ground in energy transition research and are highlighted in the International Energy Agency’s (IEA) Net Zero Emissions by 2050 (NZE) scenario [8], where lifestyle changes are expected to cut CO2 emissions and moderate the future growth in energy demand, especially in the transport and residential sectors which collectively account for a significant share of greenhouse gas emissions. Daily habits like transportation choices and residential energy use play a critical role in determining the energy patterns of societies. Examples of environmentally friendly lifestyle changes and daily habits may include the shift from private cars usage to public transportation and the adoption of energy efficient household practices by optimizing heating and cooling practices and minimizing wasteful energy consumption. These changes can contribute to reducing energy demand and CO2 emissions from the transport and residential sectors while addressing challenges associated with existing carbon-intensive assets [6] and the need for rapid growth in the clean energy supply. The above statements highlight the important role of these sectors towards delivering deep emissions reductions based on the adoption of environmentally friendly lifestyles.
The role of lifestyle changes in energy transition has been recognized [9] as an essential contributor to meeting the Paris Agreement (PA) climate targets [10]; this has triggered new research aiming to integrate lifestyle changes into energy system modeling frameworks [11] that are commonly used to assess the impacts of mitigation action. However, most studies often rely on small-scale models or regional analysis/case studies that do not fully capture the global impact of these changes, and often lack depth in how consumer behavior and lifestyle changes are represented. A comprehensive review in [11] highlighted that Integrated Assessment Models (IAMs) and Energy System Models (ESMs) have been widely used to study the broader energy transition but they often overlook a detailed representation of behavioral factors and their potential to reduce energy demand globally. Similarly, the authors of [12,13,14] emphasized that IAMs often underrepresent lifestyle changes because they rely more on technological pathways and focus on supply-side mitigation options (rather than demand-side). These limitations are also evident in [14], which presented scenarios where lifestyle changes in developed countries may lead to substantial decreases in emissions especially in the transport sector. However, this study also highlighted regional differences, noting that emissions in developing countries could further increase due to economic development and rising standards of living. Additionally, one study [15] utilized energy end-use models and cost-optimization tools to investigate the impact of lifestyle changes in the UK energy system up to 2050. Another study showed that lifestyle changes alone are insufficient to meet the UK’s 80% CO2 reduction goal [16] without further systemic changes. Moreover, a third study [17] underscores the necessity of integrating both technological measures and behavioral changes within energy modeling frameworks and scenarios to achieve deeper emissions reductions globally.
Building on these findings, in this study we use the PROMETHEUS global energy system model to analyze the role of lifestyle changes in the global energy transition. The model allows the exploration of how lifestyle shifts combined with technological advancements and climate policy measures can influence global energy consumption patterns, energy system development, and associated emissions. PROMETHEUS captures the nuances of consumer behavior and its response to policy measures, enabling a more accurate assessment of how behavioral shifts contribute to emissions reductions. This focus is particularly important given studies that show lifestyle changes alone are insufficient to meet ambitious emissions reduction targets. Moreover, PROMETHEUS was selected for this study because of its comprehensive ability to simulate the impacts of lifestyle changes on energy system dynamics over long-term horizons. This model is well-suited for capturing the interplay between supply- and demand-side factors, which is essential for analyzing the broader implications of behavioral changes, in contrast to other models that emphasize only supply-side dynamics. While alternative approaches and models exist, PROMETHEUS is perfectly suited for an in-depth examination of how lifestyle changes affect emissions and energy demand, making it an appropriate tool for the specific research objectives of this study. We combine different levels of ambition of climate policies with lifestyle changes to provide a comprehensive view of their impact in achieving a sustainable and low-carbon future and assess the potential benefits (and trade-offs) of integrating lifestyle changes into mitigation strategies. The study also provides insights of how behavior changes interact with broad decarbonization efforts, offering valuable information for policymakers and stakeholders.
The PROMETHEUS model and the scenarios examined in the study are described in Section 2. The model-based projections under the alternative scenarios are included in Section 3, while Section 4 discusses the main results and policy implications, and Section 5 describes future work and concludes the article.

2. Materials and Methods

2.1. PROMETHEUS Model Description

PROMETHEUS is an advanced global system simulation model designed to capture the complex interactions between energy demand, supply, and prices on both regional and global scale [18]. The model serves three primary objectives: (1) Assess climate change mitigation pathways and low-emission development strategies for the medium and long-term; (2) analyze the energy system and economic and emission implications of a wide spectrum of energy and climate policy measures, differentiated by region and sector; and (3) explore the economics of fossil fuel production and quantify the impacts of climate policies on the evolution of global energy prices.
PROMETHEUS delivers detailed projections of energy demand, supply, power generation mix, energy-related carbon emissions, energy prices, and investment requirements for the global energy system under alternative scenarios. As a comprehensive energy demand and supply model, it is designed to address various aspects of energy system analysis, including energy price projections, power generation planning, and climate change mitigation policies. The model integrates a broad range of variables for all the main quantities, which are of interest in the context of energy systems analysis. These include demographic and economic activity indicators, primary and final energy consumption by main fuel, fuel resources and prices, CO2 emissions, and technology dynamics (for power generation, road transport, hydrogen production, and industrial and residential end-use technologies).
PROMETHEUS quantifies CO2 emissions from fossil fuel combustion and industrial processes [19] and incorporates environmentally oriented emission abatement technologies (like various forms of renewable energy sources, electric vehicles, Carbon Capture and Storage (CCS), energy efficiency options in demand sectors, heat pumps, biofuels, hydrogen, and fuel shifts) as well as a broad range of energy and climate policy instruments. The latter include both market-based instruments, such as carbon pricing or taxation, cap and trade systems with differential application per region, and sector-specific regulatory measures focusing on specific carbon emitting activities.
PROMETHEUS describes the full energy system and CO2 emissions balances for 10 geographical regions throughout the world, including:
  • European Union (+Norway and Switzerland)
  • China
  • India
  • North America (USA and Canada)
  • Western Pacific (Japan, Republic of Korea, Australia, New Zealand)
  • Commonwealth of Independent States (e.g., the Former Soviet Union, excluding the Baltic Republics)
  • The Middle East (from the Mediterranean to the Iranian border with Afghanistan and Pakistan) and North Africa (Egypt, Libya, Tunisia, Algeria, Morocco)
  • Emerging Economies: This region broadly includes Türkiye, almost the whole of Latin America, Southeast Asia (excluding Indonesia), and Southern Africa.
  • Rest of world: All other countries, mostly in Africa and South East Asia.
Energy demand and related emissions at the world level is the sum of all regions and international air and maritime bunkers, which are represented separately.
PROMETHEUS is designed to provide medium- and long-term energy system projections and system restructuring up to 2050, from both the energy demand and supply sides. The model produces analytical quantitative results in the form of detailed energy balances annually through the period of 2020 to 2050. The model can support the impact assessment of specific energy and environment policies and measures, applied at regional and global level, including price signals, such as taxation, subsidies, technology and energy efficiency promoting policies, RES supporting policies, environmental policies, and technology or energy efficiency standards [20,21].
In this analysis, PROMETHEUS has been enhanced with an elaborate split of energy uses in buildings and transport sectors, enabling a more accurate and reliable estimation of the effects of lifestyle changes on energy service demand, energy consumption, and associated CO2 emissions for major emitters and globally. The modeling enhancements focused on disaggregating the energy consumption in the transport and residential sectors to the different energy uses and the changes in (exogenous and endogenous) model parameters to simulate the impacts of lifestyle changes (e.g., to reduce thermostat set-points in households, or replace the use of private cars with public transport and active mobility modes) [22].

2.2. Data Sources

The primary data used in this study comes from established international and European databases, including the European Commission’s EU Reference scenario 2020 and socioeconomic data from the Shared Socioeconomic Pathways (SSP2), as outlined in [23]. These sources provide comprehensive projections for GDP and population, essential for ensuring reliable baseline assumptions. In addition, the energy related data (including energy demand by sector and fuel, power generation mix, technology capacity, primary fuel production, trade, etc.) come from the IEA energy database, while CO2 energy-related emissions are derived from the EDGAR database.
The socio-economic assumptions were standardized across scenarios to facilitate comparability. For non-EU regions, PROMETHEUS used GDP and population data aligned with the SSP2 scenario, updated to include the impacts of recent historical trends, such as the COVID-19 pandemic, based on approaches described in [24]. For the EU, the socio-economic assumptions were incorporated from the EU Reference scenario 2020 [25], which aligns with the European Commission’s 2021 Ageing Report [26] and the Spring 2020 Economic Forecast [27]. These assumptions provide a consistent framework for population and economic growth projections while also using more recent data sources for the short-term projections, such as EUROPOP 2019 [28] and DG ECFIN’s Autumn Forecast 2022 [29].
Moreover, PROMETHEUS used technology data from PEU’s Reference scenario 2020 for the transport and residential sectors. This data source offers detailed, validated inputs on technology costs, efficiencies, and market trends relevant to scenario development. The technology database can be accessed at [25].
PROMETHEUS model temporal scope extends from 2015/2020 to 2050, with optional reporting beyond 2050 to evaluate long-term trends. This timeframe allows the model to capture the progressive impacts of policy and lifestyle changes. The analysis is conducted at both the EU and global levels, providing insights into the interaction of lifestyle changes and climate policies across various regions.

2.3. Scenario Design

The developed scenarios aim to cover in detail the impact of lifestyle changes on energy consumption and associated CO2 emissions under alternative climate policy contexts. They aim to reassess and improve the latest international energy, climate, and economic development pathways, with a proper integration of achievable lifestyle changes. The alternative scenarios examine the impacts of behavioral shifts in the residential and transport sectors under two climate policy contexts; the baseline (current policies) and the decarbonization scenario that meets the Paris-compatible carbon budget of 650 Gt [30] from 2020 until the year of net-zero emissions (Table 1). This study explores the additional benefits, in terms of final energy use reduction and CO2 emissions abatement, gained from shifts in consumer lifestyles at the global level and in major economies.
The design of the scenarios in this study was informed by established EU policy frameworks and targeted analysis to explore the impacts of lifestyle changes in the residential and transport sectors. In this analysis we focus on the transport and residential sectors because of their significant contribution to overall energy consumption and emissions. These sectors are critical to understanding the potential impacts of lifestyle changes because they encompass daily activities that are directly influenced by consumer behavior and policy interventions. The transport sector is a major source of GHG emissions due to its reliance on fossil fuels, and it presents considerable opportunities for emission reductions through shifts to low-carbon technologies and behavioral changes, such as increased use of public transportation or active mobility options. The residential sector, on the other hand, contributes to energy use through heating, cooling, and appliance usage. Lifestyle changes, including energy saving practices and investments in energy-efficient technologies, can lead to substantial emissions reductions in this domain.
In the PROMETHEUS model, lifestyle changes are calculated by incorporating a mix of empirical data, literature reviews, and expert insights, focused on behavioral shifts and their impact on energy consumption and carbon emissions, especially in the transport and residential building sectors. The initial step involves data collection, including feedback from the Campaigners app, which tracks energy-saving behaviors such as remote working and increased public transport use [33]. These data are complemented by findings from various studies, including the SLIM scenarios [14], which provide benchmarks for quantifying reductions in energy use and emissions. Insights from the NAVIGATE [34] project also help validate the assumptions of the study to ensure they reflect realistic and hypothetical lifestyle changes. The process of the development of lifestyle change scenarios is summarized in Table 2.
In the transport sector, reductions in private vehicle use are modeled based on remote working trends, the adoption of congestion charges, and the promotion of active transportation modes like cycling and walking. These reductions are calibrated using insights from studies such as the High Shift scenario [35], which assumes significant decreases in urban vehicle travel, although adjustments are made for rural populations where travel distances remain longer. Freight demand is reduced based on consumer behavior changes, following the Modern Trucking scenario [36], which estimates reductions in road freight activity based on decreased demand for goods. Public transport usage is expected to increase due to lifestyle changes, supported by improvements in infrastructure and policy measures like free or reduced fares. Aviation demand is assumed to decline compared to the basic scenarios, due to fuel taxes, and improved virtual connectivity, referencing the “Green Push” scenario [37]. Additionally, ride-sharing and car-sharing are modeled to increase car occupancy rates, using insights from [38], regarding the potential impact of autonomous vehicle technology on ride-sharing behavior (Table 3).
In the residential building sector, lifestyle changes are modeled through adjustments in setpoint temperature for heating and cooling. Energy savings are linked to information campaigns that promote reduced thermostat settings, based on studies such as [39] which explore the effects of smaller temperature shifts on energy use. Renovation rates are assumed to increase in the lifestyle change scenarios, leading to more energy-efficient buildings. The reduction in residential floor space per capita is modeled based on scenarios like LED/SSP1 [40,41,42], where co-housing arrangements and shared spaces reduce the overall demand for floor area. Hot water conservation is modeled by reducing shower times following similar assumptions as in [39]. The scenarios also incorporate changes in appliance use, where households adopt eco-mode settings for washing machines and dishwashers, using data from the European Product Registry for Energy Labelling [43]. Additionally, standby power consumption is modeled to decrease based on LBNL’s [44] review of standby electricity use across different appliances.
Each lifestyle change is integrated into the model by adjusting energy demand, emission factors, and technology adoption rates in the baseline and decarbonization scenarios. This allows for the assessment of how different levels of lifestyle change influence energy consumption and associated emissions by 2050. The modeling is rooted in detailed literature reviews and data from both real-world and hypothetical scenarios, ensuring that the calculations reflect realistic potential outcomes in energy transition strategies.
Overall, four scenarios (Table 4) were quantified with the PROMETHEUS energy system model, combining two climate policy contexts (baseline and decarbonization) with two assumptions for behavioral change (with or without lifestyle changes (Table 4)). The lifestyle change scenarios use specific assumptions about the various lifestyle changes in the residential and transport sectors, as discussed above and presented in Table 3. The four scenarios explored (Table 3) are named: “Base”, “Decarb”, “Base_LC”, and “Decarb_LC” with the last two referring to scenarios integrating lifestyle changes on top of baseline and decarbonization policies.
The Medium Ambition lifestyle change scenario envisions a future where a portion of consumers adopt lifestyle changes that contribute to reductions in energy consumption and carbon footprints, particularly in the transport and buildings sectors. This scenario is designed to represent a realistic yet optimistic trajectory, assuming that by 2050, a considerable shift in consumer behavior toward more sustainable living has occurred (Table 5). It should be noted however that the assumptions about behavioral changes might be optimistic, as changing human behavior is complex and often unpredictable and depends on a multitude of factors that cannot be fully quantified with the current generation of energy system modeling tools.

3. Model-Based Results

The current section describes the model-based projections for the period until 2050 under the alternative policy scenarios described above.

3.1. Impacts on Energy Consumption

Figure 1 presents the projected changes in global final energy consumption for the various scenarios described above using the PROMETHEUS model. Under the baseline scenario, PROMETHEUS projects a 44% increase in final energy consumption by 2050 compared to 2020 levels driven by rising global GDP, urbanization, and higher standards of living (particularly in emerging and developing economies). The more people gain access to private vehicles and household equipment (such as heating and cooling systems), the more energy is needed [47]. This finding is consistent with research [48] that observed similar trends of energy demand growth driven by economic development and urbanization in developing regions.
The introduction of lifestyle changes (particularly in the passenger transport and residential building sectors) moderates this energy demand growth. The adoption of more environmentally friendly behaviors (such as using public or active transport instead of private cars, adjustment of thermostat settings, reducing water heating and stand-by appliances, or reducing aviation activity) significantly influences the energy consumption patterns. In the baseline climate policy context, these behavioral shifts result in a 5% reduction in global final energy consumption by 2030 and a 10% reduction by 2050 as lifestyle changes are progressively implemented. However, the impact of decarbonization policies on final energy use is anticipated to be more substantial than that of lifestyle changes alone as shown in Figure 1.
In the Decarb scenario which incorporates ambitious climate policies, global final energy consumption is projected to decline slightly below 2020 levels by both 2030 and 2050. Specifically, global energy requirements could be reduced by 20% in 2030 and 35% in 2050 compared to baseline levels. This significant reduction is driven by the adoption of more efficient, low-carbon technologies, such as electric vehicles and heat pumps, as well as investments in energy efficient measures, including improved building insulation and industrial energy management.
When combining decarbonization policies with lifestyle changes, even greater reductions in energy demand are expected. In the Decarb_LC scenario which integrates both sets of measures, global final energy use is projected to be 7.5% lower in 2050 compared to Decarb scenario and 42% lower than the Base scenario. This approach could yield positive effects on the energy economy system, including reduced energy consumption, decreased energy imports [49], lower pressure on energy supply systems (resulting in reduced investment needs), and an overall decrease in energy system costs, encompassing both capital expenditures (CAPEX) and operating expenditures (OPEX).
Figure 2 presents the modeling results on the impacts of lifestyle changes on sectoral energy demand. As expected, the impacts on energy demand increase over time, as lifestyle change assumptions are implemented gradually in the scenarios without rapid and radical changes. This is evident in all sectors and scenarios. The impacts of integrating lifestyle changes are higher in the Base policy scenario compared to the decarbonization scenario, as the latter already involves large energy demand reductions, so the additional impact from lifestyle changes is more limited compared to the baseline scenario. In the latter, the adoption of lifestyle changes would lead to a 10% reduction of global final energy use in 2050, while in the decarbonization scenario the reduction is more limited at 7% compared to the Decarb scenario without lifestyle changes. In terms of sectors, transport registers the largest impact on energy consumption (13–19% reduction in 2050 due to lifestyle changes). This is mostly driven by the modal shifts away towards public transport and active transport modes (e.g., walking, biking) replacing the use of private cars, while aviation activity is also set to decline (replaced by high-speed rail, which is less energy intensive) and car-sharing schemes emerge with profound impacts on all regions. In the buildings sector, lifestyle changes are estimated to drive an 11–12% decline in sectoral energy demand by 2050, resulting mostly from reduced space and water heating needs due to changing thermostat set-points and higher renovation rates, but also from reduced standby power and higher eco-mode use.
Figure 3 presents the results on the impacts of lifestyle changes on energy consumption by region in 2050 both in the baseline policy and in the decarbonization context. The analysis shows that the impact of lifestyle changes is higher in the baseline context compared to decarbonization in all regions, as the latter already achieves large energy savings in all sectors and the possibilities for further demand reductions are relatively limited. The model-based analysis shows that all major emitting regions behave similarly (in terms of energy demand reductions) when lifestyle changes are adopted, as there is no large differentiation in lifestyle change assumptions across regions. However, we observe that demand savings are relatively larger in developed economies (e.g., EU, North America) as in these regions, households already consume high amounts of energy for transport and heating, as a result of their high incomes and climate factors, and there is large potential for energy savings and wide adoption of environmentally-friendly behaviors (e.g., the reduced aviation activity influences the developed economies relatively more compared to low-income countries where air traffic is very limited).

3.2. Impacts on Energy Supply

Figure 4 shows that the global power generation requirements are influenced both by the ambition of climate policy and by the assumed adoption of lifestyle changes. In the baseline scenario, PROMETHEUS shows that global power generation is projected to double over the 2020–2050 period, driven by increasing energy requirements, especially from developing countries, increasing GDP, rising standards of living, and the emergence of electric technologies in all end-use sectors (including electric cars). In the Decarb scenario, the electrification of energy and transport end-uses accelerates significantly, driven by the rapid uptake of electric vehicles, heat pumps and electrified industrial processes, and this leads to a further increase in global electricity supply compared to the baseline scenario by 5% in 2030 and 14% in 2050. The adoption of lifestyle changes would lead to reduced use of electricity (especially in residential buildings and transport), and thus global power requirements are projected to stand at about 4–6% lower in 2050 in the two lifestyle change (LC) variants compared to the basic scenarios (Base and Decarb, respectively).
The reduced electricity demand and supply would lead to lower pressure in the energy supply system, both in power generation and in transmission and distribution grids. Lifestyle changes can reduce investments required in power generating capacity, especially in decarbonization scenarios, by up to 9% in 2050 compared to the Decarb scenario without lifestyle changes (Figure 5). This showcases the important role of lifestyle changes in alleviating the pressure on the power sector in an increasingly electrified energy system. In particular, in the Decarb_LC scenario global installed power capacities are around 400 GW (2030) and 1600 (2050) GW lower than in Decarb, amounting to capital cost savings of about USD 2 trillion cumulatively by 2050. Overall, lifestyle changes can reduce electricity costs through lower capital investment in power capacities and grids and reduced fuel expenses.

3.3. Impacts on CO2 Emissions

The adoption of lifestyle changes would lead to reduced CO2 emissions both from energy supply and energy demand sectors. Figure 6 presents the scenario projections for global energy-related CO2 emissions in alternative scenarios in the period 2020–2050. The Base scenario would lead to a modest increase in global emissions, driven by increasing GDP and energy demand, combined with the relatively limited uptake of clean energy technologies in the absence of ambitious climate policies. In this context, the adoption of lifestyle changes would reduce CO2 emissions as a result of lower energy consumption and supply by around 3.5% in 2030 and 7% in 2050. The imposition of ambitious climate policies in the Decarb scenario would lead to rapid and massive emission reductions of around 43% in 2030 and 85% in 2050 below the Base scenario levels.
Decarbonization policies are the main driver for emission reductions required to meet the Paris Agreement goals. Lifestyle changes can play a complementary role to strong decarbonization policies and further reduce global emissions by 3% in 2030 and 6% in 2050 in Decarb_LC compared to Decarb scenario. Behavioral changes can support a faster transition in the medium-term and drive a reduction of cumulative emissions of around 20 GtCO2 by 2050, which may be important to alleviate part of the overall decarbonization burden and reduce residual emissions by mid-century, easing the transition towards a global net-zero economy.
The adoption of lifestyle changes by consumers would drive large CO2 reductions in the transport and buildings sectors, as these are directly influenced by the behavioral changes that consumers increasingly adopt in the LC scenarios (Figure 7). In particular, in the Base context, lifestyle changes are projected to reduce transport and buildings-related emissions by around 7–9% in 2030 and 19–20% in 2050. These changes would also drive a reduction in CO2 emissions from energy supply, which are projected to decline by around 2% in 2030 and 2050 from their Base scenario levels, as a result of reduced energy supply requirements, related both to electricity generation but also the extraction of fossil fuels and the manufacturing of petroleum products. In the decarbonization context, lifestyle changes would lead to a further reduction of emissions, especially in the buildings and transport sectors, with relatively more limited effects on supply-side emissions as energy supply is to a large extent already decarbonized through the massive uptake of renewable energy, while the impacts on emissions from the industry sector are only marginal.

3.4. Impacts on Energy System Costs

The model-based analysis shows that lifestyle changes can reduce the total energy system costs by around 4% in 2030 and 7–8% in 2050 in both baseline and decarbonization contexts. In the Base context, total energy system costs (including investment, operating and maintenance costs, costs to purchase fuels, and carbon costs) as a percentage of global GDP are projected to moderately increase by 2030 before returning to their current levels by 2050. The imposition of strong carbon pricing in the Decarb context would drive total energy system costs upwards by about 1.0–1.3% over 2020–2050, with a significant increase in investment expenditure as a result of the high capital intensity of low- and zero-carbon technologies (e.g., solar PV, wind power, electric vehicles) counterbalanced by a reduction in operating expenditure, due to reduced fossil fuel consumption in all sectors.
The adoption of lifestyle changes would reduce total energy system costs in both climate policy contexts (Figure 8). The cost savings result primarily from reduced fuel purchases in the lifestyle change variants, especially in transport and buildings sectors, and to a lesser extent from reduced capital expenditure, e.g., reduced power generation capacities and lower investment in electricity grids. In this context, lifestyle changes can be an important measure for reducing the energy import dependency of major economies, while lowering the energy bills of consumers and reducing the risk of energy poverty for vulnerable, low-income households. However, caution is needed for the interpretation of the model-based projections as the analysis does not include the costs for changing the norms and behaviors of consumers (e.g., through informational campaigns) or developing the required infrastructure to support the adoption of sustainable lifestyle changes (e.g., public transport, bike lanes) as the current literature is scarce and inconclusive in providing such cost estimates for supporting infrastructure.

4. Discussion

The PROMETHEUS results reveal significant insights into the impact of lifestyle changes on global energy demand and the broader energy system. The insertion of lifestyle changes in the current climate policy scenario moderates the projected energy demand growth resulting to a 10% reduction in final energy consumption by 2050 (Figure 2). This highlights the potential of behavioral shifts to trigger the adoption of more sustainable practices such as the increased use of public transportation, energy-efficient home heating and reduced reliance on air travel to mitigate the increasing energy demand. The importance of such behavioral changes has been also emphasized by the authors of [50], who underscored that demand side interventions (including lifestyle changes) are critical for achieving energy savings and reducing CO2 emissions to meet the Paris Agreement goals.
The current study demonstrates that ambitious climate policies have a more profound effect on energy demand than lifestyle changes alone. The implementation of stringent climate policies leads to a 35% reduction in global energy consumption by 2050 compared to the baseline (Figure 1), mainly through the adoption of low-carbon and energy-efficient technologies in all end-use sectors (buildings, transportation, and industrial processes) and energy efficiency improvements such as building retrofits, industrial energy management, and efficient appliances and lighting. The combination of ambitious climate policies and technological advancements with lifestyle changes has also been mentioned by the authors of [42] as a key option for deep decarbonization. The combination of lifestyle changes (Decarb_LC scenario) results in more pronounced demand reductions compared to the scenario without lifestyle changes. This result underscores the synergistic effect of combining behavioral changes with policy-driven technological advancements in achieving substantial energy savings by also maximizing the overall reduction of carbon emissions, as shown in [51].
The sectoral analysis further supports these findings by showing that the transport sector experiences the most significant energy consumption reductions due to lifestyle changes with a 13–19% reduction by 2050 (Figure 2). This is primarily driven by shifts away from private car usage towards public and active transport, alongside reductions in aviation activity, as seen in [52], which demonstrated the potential of modal-shifts in reducing transport-related emissions. In the residential sector, lifestyle changes would lead to an 11–12% decline in energy demand (Figure 2), mainly through more efficient heating practices and reduced stand by power usage.
The impact of lifestyle changes is more pronounced in developed economies, where higher initial energy consumption levels per capita offer greater potential for energy savings. In contrast, emerging economies, while still benefiting from lifestyle changes, show relatively smaller reductions in energy demand due to the already lower per capita consumption and the projected rapid growth in energy needs driven by economic development. This aligns with the findings of [53] that emphasized the importance of context-specific strategies in addressing energy-demand across different regions.
Lifestyle changes would also impact energy supply developments. The reduction in electricity demand due to lifestyle changes alleviates the pressure on the global power generation system and leads to lower required investments in power generation capacity and infrastructure. This is particularly evident in the Decarb_LC scenario, where a 9% reduction in installed power capacity by 2050 (Figure 5) translates into substantial cost savings, amounting to approximately USD 2 trillion cumulatively (Figure 5). Similar potential cost-savings have been also noted by IEA [54], which reported that demand-side measures could significantly reduce the need for new infrastructure and lower operational expenses. The above findings suggest that lifestyle changes not only contribute to lower energy consumption but also enhance the overall efficiency and cost-effectiveness of the energy system by reducing the need for new infrastructure and lowering operational expenses.

5. Conclusions, and Future Work

Lifestyle changes are an essential component for the clean energy transition and can complement ambitious climate policies and more technology-focused measures. Behavioral transitions towards environmentally friendly lifestyles would directly reduce energy consumption and greenhouse gas emissions, while also alleviating the pressure on the energy supply system (due to lower investment needs for power capacities and grids) and on energy producers and consumers (due to lower capital and operating expenditures). By shifting behaviors such as adopting public transportation or changing the thermostat setting in households, individuals and communities can significantly lower their carbon footprints. This is also recognized by policymakers, who are increasingly incorporating lifestyle factors into climate strategies and plans (including Nationally Determined Contributions and Long-Term Strategies), emphasizing the importance of public engagement, informational campaigns, and education in driving behavioral changes. In energy system modeling, integrating lifestyle changes into modeling tools allows for a comprehensive understanding of future energy demand and emissions scenarios.
The scenario analysis offers a crucial perspective on the interplay between lifestyle changes and climate policy. It shows that while both elements are significant to reduce emissions and achieve the Paris Agreement goals, their combined effect is more powerful in reducing global energy consumption and carbon emissions. Beyond the reductions in energy use and system costs, the findings emphasize the broader systemic benefits that lifestyle changes can bring to the global energy landscape, such as the improved resilience, reduced import dependence, lower consumer prices, and accelerated decarbonization.
This study also highlights the importance of early and sustained action. The gradual implementation of lifestyle changes alongside decarbonization efforts can create a virtuous cycle where reduced energy demand facilitates the adoption of clean energy technologies in all sectors, which in turn supports further behavioral shifts towards sustainability. This approach ensures meeting ambitious climate targets and enhances energy security by lowering the dependence on energy imports and stabilizing energy prices.
In addition to the environmental benefits in terms of reduced emissions and air pollution, the promotion of environmentally-friendly lifestyle changes has the potential to foster a culture of sustainability that transcends individual sectors and regions by influencing broader societal values and behaviors. This cultural shift could pave the way for more comprehensive solutions to global energy challenges that make sustainability an integral part of daily life and decision-making processes of citizens. The study also underscores the necessity of carefully integrating lifestyle considerations into medium- and long-term system planning and climate policy making (e.g., in the new NDCs to be submitted in 2025, or the national long-term targets). By doing so, governments and other organizations can create more holistic strategies that address the root causes of energy demand and contribute to the creation of a sustainable, low-carbon future for all.
Beyond the model-based insights provided in this study, it is essential to acknowledge the broader context of implementing lifestyle changes to achieve significant emissions reductions. Practical strategies for the adoption of lifestyle changes include policy measures such as financial initiatives including subsidies and tax rebates for energy-efficient home retrofitting, energy-efficient home appliances and investments in public transportation infrastructure. Public engagements and education campaigns are also crucial to encourage sustainable behaviors at the community level. Government-led awareness campaigns can educate the public on the benefits of sustainable behaviors, fostering a culture of energy conservation [55]. The effectiveness of stricter emissions standards and the implementation of low-emissions zones are examined in [56], which highlighted that these measures can significantly enhance the transition to cleaner transportation options. However, potential barriers to widespread adoption of lifestyle changes must be considered. These include, among others, economic constraints faced by lower-income households, resistance to behavioral change, and limitations in existing infrastructure. Future work can better align modeling outcomes with real-world applications to address the above challenges.
While the current study provides valuable insights into the potential impacts of lifestyle changes and decarbonization policies, several areas need further research to enhance our understanding and inform policy making. Future studies should delve deeper into the behavioral dynamics that drive lifestyle changes, particularly in different cultural and socioeconomic contexts. The varying impacts across different economies should be explored in greater detail considering equity implications and the specific challenges faced by developing countries in balancing economic growth with sustainable energy use. Although this area has been touched upon by [50], more work is needed to understand how these factors interact in different regions, especially in developing economies where lifestyle changes may have different implications. Moreover, it is important to acknowledge that more robust sensitivity analysis could further enhance the understanding of these findings. Future research should consider incorporating comprehensive sensitivity analysis to examine how variations in key parameters about lifestyle changes might influence the results. This could validate the robustness of scenario outcomes and strengthen the applicability and reliability of model-based insights for decision-making. Finally, as lifestyle changes are widely recognized as key component of the energy transition, future work should focus on developing more sophisticated models that capture the complex interactions between behavior, technology, and policy. This could include the improvement of representation of social dynamics in IAMs and ESMs, as also highlighted in [41].

Author Contributions

Conceptualization, P.F., E.Z. and A.A.; methodology, P.F., E.Z. and A.A.; software, P.F.; validation, P.F., E.Z. and A.A.; formal analysis, P.F., E.Z. and A.A.; investigation, P.F., E.Z. and A.A.; resources, P.F., E.Z. and A.A.; data curation, P.F., E.Z. and A.A.; writing—original draft preparation, P.F., E.Z. and A.A.; writing—review and editing, P.F., E.Z. and A.A.; visualization, P.F., E.Z. and A.A.; supervision, P.F.; project administration, P.F.; funding acquisition, P.F. All authors have read and agreed to the published version of the manuscript.

Funding

This research was funded by the [CAMPAIGNers project] grant number [101003815] and the [Multifutures project] grant number [101137713].

Data Availability Statement

Data in the study are available upon request.

Acknowledgments

The research leading to this study has received funding from the CAMPAIGNers project, funded under the European Union’s Horizon 2020 research and innovation programme GA No: 101003815, and the Multifutures project, funded under the European Union’s Horizon Europe programme GA No: 101137713.

Conflicts of Interest

The authors declare no conflict of interest.

Glossary

NOAMNorth America (USA, Canada)
WPACWestern Pacific (Japan, Republic of Korea, Australia, New Zealand)
CHNChina
INDIndia
CISRussia and Community of Independent States
RestRest of the world.

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Figure 1. Global final energy demand in alternative scenarios over 2020–2050. Source: PROMETHEUS model.
Figure 1. Global final energy demand in alternative scenarios over 2020–2050. Source: PROMETHEUS model.
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Figure 2. Impacts of lifestyle changes on sectoral energy demand in 2030 and 2050.
Figure 2. Impacts of lifestyle changes on sectoral energy demand in 2030 and 2050.
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Figure 3. Impacts of lifestyle changes on regional energy demand in 2050.
Figure 3. Impacts of lifestyle changes on regional energy demand in 2050.
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Figure 4. Global power generation in alternative scenarios over 2020–2050.
Figure 4. Global power generation in alternative scenarios over 2020–2050.
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Figure 5. Global power capacity savings in Decarb_LC scenario compared to Decarb.
Figure 5. Global power capacity savings in Decarb_LC scenario compared to Decarb.
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Figure 6. Global energy-related CO2 emissions in alternative scenarios.
Figure 6. Global energy-related CO2 emissions in alternative scenarios.
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Figure 7. Impacts of lifestyle changes on CO2 emissions by sector in 2030 and 2050.
Figure 7. Impacts of lifestyle changes on CO2 emissions by sector in 2030 and 2050.
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Figure 8. Impacts on lifestyle changes on energy system costs.
Figure 8. Impacts on lifestyle changes on energy system costs.
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Table 1. Summary of climate targets integrated in the scenarios.
Table 1. Summary of climate targets integrated in the scenarios.
ScenarioDesign and RationaleSource of Targets and Policies
Baseline (Base)This scenario represents the continuation of existing climate policies, reflecting the National Energy and Climate Plans (NECPs) and Long-Term Renovation Strategies of EU countries and currently implemented policies as described in [24]. Policies are compatible with the latest EU Reference scenario which provides a benchmark for assessing energy, environmental and climate projections. Non-EU countries follow their currently implemented policies [31].The EU Reference scenario data and methodologies were used to capture existing commitments, targets, and measures of the latest available data, including policies like the Renewable Energy Directive (RED II) and the Energy Efficiency Directive (EED). For non-EU countries, currently implemented policies from the basis, drawing on international databases and policy reviews to represent each country’s commitments to climate and energy policy.
Decarbonization (Decarb)This scenario is structured to model the pathway required to meet stringent climate targets that align with limiting global warming to 1.5 °C. The decarbonization pathway is informed by a global carbon budget of 650 Gt CO2 from 2020–2100 (which is imposed globally to limit global warming to 1.5 °C) (based on IPCC, AR6) [32]. This budget constraint imposes a reduction trajectory designed to ensure compatibility with ambitious temperature targets globally. Within the EU, the scenario incorporates the 55% GHG reduction target by 2030, in line with the European Climate Law and the Fit for 55 package. This includes specific policies aimed at increasing renewable energy and energy efficiency, while also integrating carbon pricing mechanisms through the EU Emission Trading System (ETS) for both ETS1 and ETS2 sectors. The scenario reflects key measures outlined in the Fit For 55 legislative package, including updates to the ETS, the Social Climate Fund, and sector-specific regulatory measures for transport, industry, and buildings. Additionally, the carbon budget and policy measures are derived from a combination of IPCC recommendations for a 1.5 °C pathway and the EU policy documents (e.g., the European Green Deal and Climate Target Plan 2030), as well as insights from sectoral studies on decarbonization in the EU.
Table 2. Development of lifestyle changes scenarios.
Table 2. Development of lifestyle changes scenarios.
StepProcessDescription
1Empirical data and survey insightsData from user-driven sources, including the Campaigners app, provided real-world insights into current and potential future behavior patterns. These data [11] highlighted trends in energy consumption, transport choices, and home energy efficiency practices, serving as a foundation for realistic lifestyle scenarios.
2Behavioral literature and best practicesThe scenarios were informed by studies on sustainable behaviors and adoption rates of lifestyle changes, with reference to documented trends in behavioral economics and social sciences. This literature provided parameters for likely shifts in areas like public transport adoption, reduced car dependency, and increased use of energy-saving appliances.
3Scenario development with tiered ambition levelsNo change (Baseline): Assumes no significant behavior shifts, reflecting a continuation of current practices
Medium Ambition: Incorporates moderate lifestyle adjustments, such as modest increases in public and active transport and gradual adoption of energy-efficient appliances.
4Integration into the PROMETHEUS modelThe scenarios were then modeled in PROMETHEUS by adjusting parameters related to energy demand intensity, transport modal share, and technology uptake in accordance with each lifestyle scenario to allow for the assessment of direct and indirect impacts of these lifestyle changes on energy use and emissions.
Table 3. Assumptions about the various lifestyle changes included in the PROMETHEUS model.
Table 3. Assumptions about the various lifestyle changes included in the PROMETHEUS model.
SectorDomainLifestyle CategoryMost Important Lifestyle Changes
TransportMobilityTransport-mode shiftsShift from private cars to public transport
Shift from airplane to high-speed trains
Shift to active modes of transport
Shared-mobility Carpool commuting
Car-sharing (mobility-as-a-service)
Driving habitsEco-driving practices
ResidentialThermal Comfort“Avoid” energy-demand actionsConservation of hot water for showering, clothes, and dish washing
Adjustment of thermostat-temperature set points
Living in smaller dwellings
Table 4. Alternative scenarios modeled with PROMETHEUS.
Table 4. Alternative scenarios modeled with PROMETHEUS.
ScenarioClimate TargetLifestyle Changes
BaseCurrent climate policies in the EU and globally [45]No changes
Base_LCCurrent climate policies in the EU and globally Medium Ambition of lifestyle changes
DecarbGlobal decarbonization to meet Paris goals [46]; EU Climate neutrality in 2050; Fit for 55 targets in 2030No changes
Decarb_LCGlobal decarbonization to meet Paris goals; EU Climate neutrality in 2050; Fit for 55 targets in 2030Medium Ambition of lifestyle changes
Table 5. Lifestyle change scenario assumptions (changes from the levels of baseline and decarbonization scenarios without lifestyle changes in 2050).
Table 5. Lifestyle change scenario assumptions (changes from the levels of baseline and decarbonization scenarios without lifestyle changes in 2050).
SectorModeled Lifestyle ChangesMedium Ambtion Lifestyle Change
TransportDemand for private vehicle useA 10% reduction in passenger kilometers(pkm) for private cars by 2050, driven by congestion changes, remote working trends, and increased urban planning that favors alternative modes of transport.
Road freight activityA 7% reduction in road freight activity in 2050 compared to the baseline due to the reduction in consumer demand for goods.
Share of active modesThe share of active modes, such as walking, cycling and e-scooters, increases linearly to 5% of total pkm by 2050, encouraging healthier and more sustainable urban mobility.
Share of public transportPublic transport usage grows, with its share of pkm increasing by 10 percentage points compared to the baseline.
Passenger aviation activityA 15% reduction of aviation passenger activity by 2050 due to policies like fuel taxes, frequent flyer levies, and improved virual connectivity, encouraging people to choose less carbon-intensive forms of travel.
Ride and car sharingA 20% increase in occupancy rate of private cars by 2050 compared to baseline, facilitated by ride-sharing programs, autonomous vehicle technology, and carpooling incentives that reduce the need for individual car ownership and travel.
Residential buildingsSetpoint temperatureA 1 °C shift of thermostat setting for both heating (20 °C) and cooling (25 °C) is assumed, reflecting a moderate adoption of energy-saving behaviors in residential heating and cooling.
Renovation ratesAnnual renovation rates increase by 0.5 percentage points above the baseline, improving building energy efficiency.
Limiting floor spaceThe per capita residential floor space gradually converges to 40 m2 by 2050, emphasizing the trend towards shared living spaces and flexible building use.
Hot water conservationShower times are limited to 5 min by 2050, indicating a shift to water- and energy-efficient personal hygiene habits.
Stand-by powerAbout 50% of households eliminate standby power consumption by 2050, contributing to a reduction in electricity demand.
Eco-mode consumptionAbout 50% of households switch to eco-mode for clothes and dishwashing programmes by 2050, reducing their energy consumption per cycle.
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Fragkos, P.; Zisarou, E.; Andreou, A. Exploring the Impacts of Lifestyle Changes in the Global Energy Transition: Insights from a Model-Based Analysis Using PROMETHEUS. Climate 2024, 12, 193. https://doi.org/10.3390/cli12120193

AMA Style

Fragkos P, Zisarou E, Andreou A. Exploring the Impacts of Lifestyle Changes in the Global Energy Transition: Insights from a Model-Based Analysis Using PROMETHEUS. Climate. 2024; 12(12):193. https://doi.org/10.3390/cli12120193

Chicago/Turabian Style

Fragkos, Panagiotis, Eleftheria Zisarou, and Andreas Andreou. 2024. "Exploring the Impacts of Lifestyle Changes in the Global Energy Transition: Insights from a Model-Based Analysis Using PROMETHEUS" Climate 12, no. 12: 193. https://doi.org/10.3390/cli12120193

APA Style

Fragkos, P., Zisarou, E., & Andreou, A. (2024). Exploring the Impacts of Lifestyle Changes in the Global Energy Transition: Insights from a Model-Based Analysis Using PROMETHEUS. Climate, 12(12), 193. https://doi.org/10.3390/cli12120193

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