Life Cycle Energy Use Research Articles

Digital Twin Technology in Built Environment: A Review of Applications, Capabilities and Challenges

Digital Twin (DT) technology is a pivotal innovation within the built environment industry, facilitating digital transformation through advanced data integration and analytics. DTs have demonstrated significant benefits in building design, construction, and asset management, including optimising lifecycle energy use, enhancing operational efficiency, enabling predictive maintenance, and improving user adaptability. By integrating real-time data from IoT sensors with advanced analytics, DTs provide dynamic and actionable insights for better decision-making and resource management. Despite these promising benefits, several challenges impede the widespread adoption of DT technology, such as technological integration, data consistency, organisational adaptation, and cybersecurity concerns. Addressing these challenges requires interdisciplinary collaboration, standardisation of data formats, and the development of universal design and development platforms for DTs. This paper provides a comprehensive review of DT definitions, applications, capabilities, and challenges within the Architecture, Engineering, and Construction (AEC) industries. This paper provides important insights for researchers and professionals, helping them gain a more comprehensive and detailed view of DT. The findings also demonstrate the significant impact that DTs can have on this sector, contributing to advancing DT implementations and promoting sustainable and efficient building management practices. Ultimately, DT technology is set to revolutionise the AEC industries by enabling autonomous, data-driven decision-making and optimising building operations for enhanced productivity and performance.

Primary Energy and Carbon Impacts of Structural Frames with Equivalent Design Criteria: Influence of Different Materials and Levels of Prefabrication

This study aims to analyze the life-cycle primary energy and climate impacts of structural frames, paying particular attention to the design and prefabrication of different structural materials. The study considers an existing single-story office building with a composite concrete–steel structure and compares it with two functionally equivalent structures, i.e., a conventional reinforced concrete structure and a conventional steel structure. The existing building is located in San Felice sul Panaro, Italy. This study integrates dynamic structural analysis and life-cycle assessment (LCA). The study finds that the use of different materials can reduce the life-cycle primary energy use and CO2-eq emissions by up to 12%. Furthermore, the benefits derived from the recovery and recycling of materials can reduce the primary energy use and CO2-eq emissions by up to 47% and 36%, respectively. The prefabrication of structural elements can also reduce the primary energy use and CO2-eq emissions in the construction stage. A sensitivity analysis considers changes in the electricity supply system and shows that the primary energy and CO2-eq emissions due to prefabrication decrease when assuming marginal electricity based on renewable energies. This analysis supports the development of sustainable structural design to meet the standards concerning the whole-life-cycle carbon emissions of buildings.

Embodied impacts of buildings from energy-carbon-water nexus perspective: A case study of university buildings

Despite extensive investment in energy efficiency efforts, the energy footprint of the building sector still contains over 40 % of the world's annual consumption of energy. Although most of a building's life cycle energy use comes from operational activities, a portion of it stems from embodied energy (EE), which is directly expended in a building's construction and indirectly consumed using materials. Because each material consumes not only different amounts but also different types of energy sources, studying embodied carbon (EC) is equally important. The building construction sector also consumes nearly 1/5th of global fresh water, which is becoming a grave concern, given the increasing frequency of droughts and wildfires. The fact that material manufacturing and construction processes also consume water makes it essential to not just assess energy and carbon but also embodied water (EW). The literature recommends evaluating total EW including direct and indirect EW as well as any EW associated with EE use. In this paper, macroeconomic models are utilized to compute and analyze the energy, carbon emission, and water embodied in four university buildings. The results show that the total EE, EC, and EW values for the four case study buildings vary from 13.1 to 51.1 GJ/m2, 1.4–10.0 kgCO2/m2, and 2,820–12,900 gal./m2, respectively. The EE values also show a near perfect positive correlation with EW values. However, the share of EREW in the total EW ranges from 13 % to 16 %, indicating that a decrease in EE use may not help decrease a majority of EW.

Climate impact and energy use of structural battery composites in electrical vehicles—a comparative prospective life cycle assessment

PurposeStructural battery composites (SBCs) are multifunctional carbon fibre composites that can be used as structural elements in battery electric vehicles to store energy. By decreasing the weight of the vehicle, energy consumption in the use phase can be reduced, something that could be counteracted by the energy-intensive carbon fibre production. The purpose of this study is to shed light on such life-cycle considerations.MethodProspective life cycle assessment is used to compare the future cradle-to-grave climate impact and energy use of SBCs in battery electric vehicles to conventional metals and lithium-ion batteries. Additionally, the influences from different technology development routes, primarily related to the carbon fibre production, are assessed. The functional unit is the roof, hood, and doors of a battery electric vehicle with maintained flexural stiffness used for 200,000 km. To capture the multifunctionality of the material, the lithium-ion battery is also included in the functional unit.Results and discussionResults show that SBCs have a large potential to decrease the life cycle climate impact and energy use of battery electric vehicles, especially following routes focusing on decreasing the use of fossil resources, both for raw materials and as energy sources. The comparative assessment of multifunctional or recycled materials to conventional materials introduces several methodological challenges, such as defining the functional unit and choice of allocation approach for distributing burdens and benefits between life cycles in recycling. This study illustrates the importance of using both the cut-off and end-of-life recycling allocation approaches to capture extremes and to not provide biased results. This study also highlights the importance of considering the ease of repairability in comparative studies, as damages to car parts made from SBCs are likely more difficult to repair than those made from conventional materials.ConclusionsSBCs have the potential to reduce the life cycle climate impact and energy use for most scenarios compared to conventional materials. Three main methodological challenges were found: the comparison to a material with a well-established recycling system throughout its life cycle, the need for expanding the system boundaries to include the lithium-ion battery, and the difference in repairability of SBCs compared to the conventional material.

Life cycle energy use efficiency and greenhouse gas emissions of circulating fluidized bed coal-fired plant with coal gangue and coal co-combustion

Life cycle energy use efficiency and greenhouse gas emissions of circulating fluidized bed coal-fired plant with coal gangue and coal co-combustion

Life cycle analysis of the economic costs and environmental benefits of photovoltaic module waste recycling in China

China will face great challenges related to PV waste in the coming decades. Mechanical recycling (MR), chemical recycling (CR), and thermal recycling (TR) are widely regarded as future technologies for PV recycling; however, knowledge about their costs and benefits remains unexplored in China. In this study, the costs and benefits of these technologies are comprehensively assessed and compared using a life cycle assessment (LCA). The results showed that MR, CR, and TR had the smallest amounts of life-cycle energy use (−28,949 MJ/ton), industrial water use (−65,069 kg/ton), and global warming potential (−5525 kg CO2 eq/ton), respectively. To date, cost-benefit analyses have demonstrated PV recycling was expensive. Overall, all three PV-recycling technologies show superior environmental and economic performance compared with landfilling. Scenario analysis showed that improvements in technology, expansion of the recycling scale, reducing transport distances, and subsidization are all effective measures for enhancing the total benefits of PV waste recycling.

Life cycle energy use and greenhouse gas emissions for a novel algal-osmosis membrane system versus conventional advanced potable water reuse processes: Part I

This study applied a life cycle assessment (LCA) methodology for a comparative environmental analysis between an innovative algae resource recovery and near zero-liquid discharge potable reuse system (i.e., the main system) versus a conventional potable reuse system (i.e., the benchmark system) through energy use and greenhouse gas (GHG) emissions. The objective of this study is to demonstrate that pilot-scale data coupled with LCA would provide valuable information for system optimization, integration, and improvements for the design of environmentally sustainable full-scale systems. This study also provides decision-makers valuable information regarding the energy demand and environmental impact of this innovative main system compared to a typical tried-and-true system for potable water reuse. The main system consists of a novel algal-based wastewater treatment coupled with a dual forward osmosis and seawater reverse osmosis (Algal FO-SWRO) membranes system for potable water recovery and hydrothermal liquefaction (HTL) to recover biofuels and valuable nutrients from the harvested algal biomass. The benchmark system refers to the current industry standard technologies for potable water reuse and waste management including a secondary biological treatment, microfiltration (MF), brackish water reverse osmosis (BWRO), ultraviolet/advanced oxidation process (UV-AOP), and granular activated carbon (GAC), as well as anaerobic digestion for sludge treatment. Respective energy and GHG emissions of both systems were normalized and compared considering 1 m3 of water recovered. Based on an overall water recovery of 76% designed for the benchmark system, the energy consumption totaled 4.83 kWh/m3, and the system was estimated to generate 2.42 kg of CO2 equivalent/m3 with most of the emissions coming from the biological treatment. The main system, based on an overall water recovery of 88%, was estimated to consume 4.76 kWh/m3 and emit 1.49 kg of CO2 eq/m3. The main system has high environmental resilience and can recover bioenergy and nutrients from wastewater with zero waste disposal. With the application of energy recovery devices for the HTL and the SWRO, increase in water recovery of the FO membrane, and replacement of the SWRO membrane with BWRO, the main system provides an energy-competitive and environmentally positive alternative with an energy demand of 2.57 kWh/m3 and low GHG emissions of 0.94 kg CO2 eq/m3.

Embodied energy in existing buildings as a tool for sustainable intervention on urban heritage

In the context of worldwide efforts towards energy efficiency and circular economy, embodied energy has been increasing its weight in the total lifecycle energy use of buildings. By investigating the context and the extent to which it is crucial to calculate embodied energy quantities for existing buildings, this paper investigates the concept itself of embodied energy in existing buildings as an untapped potential for driving sustainable renovation and reuse of urban environments. A new research gap concerning the embodied energy in existing buildings emerges from a critical literature review. A new comprehensive approach for definition and calculation of embodied energy that integrates both retroactive and prospective perspectives is proposed within two boundary systems expressed in terms of life-cycle energy analysis.This approach outlines the potential role of embodied energy in supporting decision at city-level regarding adaptive reuse or demolish-rebuild scenarios on buildings as part of urban heritage. Results investigates the extent to which embodied energy stored in our urban heritage should be considered as a decision parameter to prioritize preservation and reuse interventions among the large number of existing buildings composing the present and the future built environment, delineating new open issues forfurther research.

Ultraviolet-based heterogeneous advanced oxidation processes as technologies to remove pharmaceuticals from wastewater: An overview

Contaminants of emerging concern including pharmaceuticals and personal care products are increasingly detected at low concentrations in surface waters. Given the associated toxicity of these compounds, there is the potential for significant impacts on aquatic life and the food chain. Since most pharmaceuticals are not biodegradable, they cannot be removed by secondary treatment processes in conventional wastewater treatment plants. Therefore, the development of alternative treatment methods plays a critical role in the removal of pharmaceuticals. Energy consumption is a key factor in technology selection, and the use of solar energy may help minimise operating costs. Thus, this work provides a comprehensive review of relevant research published between 2016 and 2021 targeting the removal of active pharmaceutical ingredients using ultraviolet processes, including photo-Fenton, photocatalysis and photoelectrocatalysis. While the focus remains on the development of novel catalysts and some efforts have been made to demonstrate the reuse of these materials for multiple cycles, there is little work aimed at scaling up the systems or investigating their efficacy in real water matrices to test the potential beyond the laboratory setting. The review concludes with some recommendations for future studies, highlighting the importance of comparing technologies in terms of life cycle assessment, energy use, and financial considerations to provide a holistic understanding of the role that these technologies can play in removing trace pharmaceutical compounds from wastewater.

How does COVID-19 affect the life cycle environmental impacts of U.S. household energy and food consumption?

The COVID-19 pandemic has reduced travel but led to an increase in household food and energy consumption. Previous studies have explored the changes in household consumption of food and energy during the pandemic; however, the economy-wide environmental implications of these changes have not been investigated. This study addresses the knowledge gap by estimating the life cycle environmental impacts of U.S. households during the pandemic using a hybrid life cycle assessment. The results revealed that the reduction in travel outweighed the increase in household energy consumption, leading to a nationwide decrease in life cycle greenhouse gas emissions (−255 Mton CO2 eq), energy use (−4.46 EJ), smog formation (−9.17 Mton O3 eq), minerals and metal use (−16.1 Mton), commercial wastes (−8.31 Mton), and acidification (−226 kton SO2 eq). However, U.S. households had more life cycle freshwater withdrawals (+8.6 Gton) and slightly higher eutrophication (+0.2%), ozone depletion (+0.7%), and freshwater ecotoxicity (+2.1%) caused by increased household energy and food consumption. This study also demonstrated the environmental trade-offs between decreased food services and increased food consumption at home, resulting in diverse trends for food-related life cycle environmental impacts.

Life cycle energy of vehicles on lightweighting and alternative powertrain strategies—A review

To improve vehicles environmental performance, different strategies have been explored namely to reduce the use stage energy. In order to avoid problem shifting, a life cycle perspective should be used to compare alternative solutions. This paper aims to compare existing studies focused on life cycle energy (LCE) of vehicles to analyze the impacts and benefits regarding two trending improvement strategies: lightweight materials and alternative powertrain selection. A Literature review was performed to systematize quantitatively the LCE results of different studies (e.g. presented among figures, tables, and literature text). The LCE results were compiled and normalized for the same driving distance, 200 000 km, per life cycle stage. Moreover, the study discusses research findings on the application of the two strategies to improve overall vehicles’ LCE. As lightweight materials have generally higher embodied energy, the material selection is highly influenced by end-of-life scenarios. It was observed that carbon/glass fiber composites generally have the highest embodied energy, being a preferable option for vehicles that last longer driving distances. Innovative powertrains sourced by renewable energy sources, electric mixes, can significantly reduce vehicles’ LCE use stage, counteracting the benefit of lightweight design. Thus, the benefit of both strategies should be studied together.

Life Cycle Energy Use and Greenhouse Gas Emissions for a Novel Algal-Osmosis Membrane System Versus Conventional Advanced Potable Water Reuse Processes: Part I

Life Cycle Energy Use and Greenhouse Gas Emissions for a Novel Algal-Osmosis Membrane System Versus Conventional Advanced Potable Water Reuse Processes: Part I

Reducing Life Cycle Material and Energy Use and Emissions for Liquid Consumer Products Through Printed Cups

Reducing Life Cycle Material and Energy Use and Emissions for Liquid Consumer Products Through Printed Cups

Two-Stage Lifecycle Energy Optimization of Mid-Rise Residential Buildings with Building-Integrated Photovoltaic and Alternative Composite Façade Materials

Reducing the lifecycle energy use of buildings with renewable energy applications has become critical given the urgent need to decarbonize the building sector. Multi-objective optimizations have been widely applied to reduce the operational energy use of buildings, but limited studies concern the embodied or whole lifecycle energy use. Consequently, there are issues such as sub-optimal design solutions and unclear correlation between embodied and operational energy in the current building energy assessment. To address these gaps, this study integrates a multi-objective optimization method with building energy simulation and lifecycle assessment (LCA) to explore the optimal configuration of different building envelopes from a lifecycle perspective. Major contributions of the study include the integrated optimization which reflects the dynamics of the whole lifecycle energy use. Insights from the study reveal the optimal configuration of PV and composite building façades for different regions in sub-Saharan Africa. The lifecycle energy use for the optimized building design resulted in 24.59, 33.33, and 36.93% energy savings in Ghana, Burkina Faso, and Nigeria, respectively. Additionally, PV power generation can efficiently cover over 90% of the total building energy demand. This study provides valuable insights for building designers in sub-Saharan Africa and similar areas that minimize lifecycle energy demand.

Impact of the use of recycled materials on the energy conservation and energy transition of buildings using life cycle assessment: A case study in South Korea

This study was conducted to ascertain how the use of recycled materials instead of virgin materials affect the installation of renewable energy systems for the energy transition of buildings. LCA was used to estimate the life cycle energy use and GHG emissions of building and renewable energy systems with and without using recycled materials. For the case study, a public building and four representative photovoltaic (PV) systems were selected. National recycling standards and processes were considered for suggested recycled materials. In general, replacing virgin material with recycled counterpart reduced embodied GHG emissions more than embodied energy. However, due to high carbon intensity of operation energy and building materials without available counterparts, using recycled materials reduced the life cycle energy use and GHG emissions of the case building by 4.9% and 3.3%. Among four PV systems, using recycled materials was most significant in the single crystalline-silicon (sC-Si) PV system, 44.5% reduction of energy use and 41.3% reduction of GHG emissions. Therefore, when recycled materials are used for achieving the energy transition of the case building with the sC-Si PV system, the PV system requirements could be reduced by a maximum of 9.6% for energy payback and 4.9% for GHG payback. This study demonstrated that the use of recycled materials is effective at reducing the embodied energy and GHG emissions of PV systems as well as buildings. To achieve carbon-neutral buildings, particularly, the use of recycled materials based on a thorough LCA should be considered in addition to renewable energy system.

The role of climate change and decentralization in urban water services: A dynamic energy-water nexus analysis

Urban water services, including drinking water supply and wastewater treatment, are highly energy dependent, contributing to the challenges described under the water-energy nexus. Both future climate change and decentralized water system adoptions can potentially influence the energy use of the urban water services. However, the trend and the extent of such influences have not been well understood. In this study, a modeling framework was developed to quantify both the separate and the combined influences of climate change and decentralization on the life cycle energy use of the urban water cycle, using the City of Boston, MA as a testbed. Two types of household decentralized systems were considered, the greywater recycling (GWR) systems and the rainwater harvesting (RWH) systems. This modeling framework integrates empirical models based on multilinear regression analysis, hydrologic modeling, water balance models, and life cycle assessment to capture the complex interactions among centralized water services, decentralized water system adoptions, and climate parameters for cumulative energy demand (CED) assessment, considering all residential buildings in Boston. It was found that climate change alone will slightly increase the energy use of the centralized systems towards the end of the century, due to the cancelation effect amongst changes in water quality, flow rate, and space and water heating demand. When decentralization is considered alone, we found economically viable decentralized systems may not necessarily produce energy savings. In fact, RWH adoptions may increase energy use. When climate change and decentralization are combined, they will increase the water yield and cost savings of the decentralized systems, while reducing the energy use from the centralized systems. When the centralized systems are further added into the picture, the CED of the entire urban water cycle is projected to increase by 0.9% or 2.3% towards the end of the century under climate change if GWR or RWH systems are adopted by respective cost saving positive buildings.

Life cycle embodied, operational and mobility-related energy and greenhouse gas emissions analysis of a green development in Melbourne, Australia

At least 40% of total greenhouse gas emissions are related to the built environment, mostly because of energy coming from fossil fuels. In response, developments with an improved energy efficiency (e.g. so-called ‘green’ or ‘net-zero energy’ developments) have been built. Despite reductions in operational energy use in ‘green’ developments, previous studies have identified trade-offs in terms of embodied energy in construction materials and sometimes transport energy associated with the mobility of building users.This research reconsiders the evaluation of green environmental claims through a life cycle approach. A multi-scale life cycle energy assessment software tool is employed to quantify the energy use and greenhouse gas emissions of a case study medium-scale green development in Melbourne, Australia over 50 years. Results show that the total life cycle energy use and greenhouse gas emissions of the development are 1,492 TJ (2,688 GJ per capita and 107 GJ/m2 of GFA) and 81 ktCO2-e (146 tCO2-e per capita and 6 tCO2-e/m2 of GFA), respectively, compared to 2,220 TJ (4,001 GJ per capita and 159 GJ/m2 of GFA) and 177 ktCO2-e (318 tCO2-e per capita and 13 tCO2-e/m2 of GFA) for a business-as-usual development with the same geometry. In fact, each of the embodied, operational and transport energy requirements represents an important contribution to the life cycle energy: 31%, 35% and 34%, respectively. Therefore, all life cycle stages and scales of the built environment are relevant to the overall energy and greenhouse gas emissions performance of green developments.

An integrated optimization and sensitivity analysis approach to support the life cycle energy trade-off in building design

The building design process plays a central role in efforts to implement energy-efficient practices. However, unilateral design choices based solely on reducing operational energy use can significantly increase a building’s embodied energy and life cycle energy use as there is a trade-off between embodied and operational energy. To support such trade-off problems, multi-objective optimization represents a useful approach that produces a set of optimal solutions from where a solution can then be selected and progressed within the design process. Selecting one solution from the set of optimal solutions can however be a challenging task as each solution has the potential to be chosen as the optimum. Therefore, the purpose of this study was to explore how solutions from a multi-objective optimization approach can be analyzed further to provide information to decision-makers when selecting the optimal design solution. An approach is proposed where the integration of post-optimization sensitivity analysis into a multi-objective optimization approach aims to support decision-makers in analyzing the optimal solutions provided by the optimization process. The applicability of approach is demonstrated using a case of a multifamily apartment building located in Sweden, where the aforementioned trade-off is explored for a set of energy efficiency measures. Thereby, a diverse range of optimal solutions that could result in up to 4520 GJ life cycle energy (LCE) savings relative to the case building’s initial design was initially identified using the multi-objective optimization. These solutions were then subjected to a sensitivity analysis where the results indicated that in general the lowest and highest sensitivity in terms of LCE use belonged to the insulation thicknesses in roof and walls, respectively. Furthermore, the thickness of exterior floor insulation yielded the greatest variation in the sensitivity. The findings of case study indicate that the post-optimization sensitivity analysis can add valuable information that complements the results obtained using a multi-objective optimization approach. Consequently, it can support decision-making on how to progress with the design in terms of what design parameters have a negligible or significant impact on the objectives when they are varied, thus facilitating prioritization.

Utilizing high-purity carbon dioxide sources for algae cultivation and biofuel production in the United States: Opportunities and challenges

Carbon dioxide (CO2) supply is an important consideration for algae production systems, and using high-purity CO2 eliminates the need for purification processes. This study assessed the challenges and opportunities inherent in using waste high-purity CO2 to produce algae in the United States. The United States’ upper Midwest region is rich in high-purity CO2 from corn ethanol production. However, its climate is not as favorable for algae production as that on the Gulf Coast. This study assessed the tradeoffs between these factors by comparing algae biofuel production with and without high-purity CO2 across these two regions. Monthly algae cultivation was modeled in open ponds co-located with high-purity CO2 sources in the Midwest and along the Gulf Coast, where many steam methane reforming and ammonia production facilities are located. This revealed that, by avoiding the energy-intensive carbon-capture process, an algae site that sources carbon from a high-purity CO2 source would achieve a 9–39% reduction in life-cycle greenhouse gas (GHG) emissions and a 9–37% reduction in life-cycle fossil energy use compared to a similar site using dilute CO2 for algae cultivation. The results also suggest that during warm months an algae pond in the Midwest would achieve results that are comparable to GHG emissions from a pond on the Gulf Coast. Furthermore, several Midwest algae ponds investigated in this study create less local water stress than those located along the Gulf Coast. The abundant high-purity CO2 from corn ethanol plants thus creates a potential opportunity for algae cultivation in the Midwest. This study illustrated the interplay between algae productivity, CO2 delivery, GHG emissions, and water stress in siting algae ponds.

A Comprehensive Framework for Standardising System Boundary Definition in Life Cycle Energy Assessments

This paper aims to propose a comprehensive framework for a clear description of system boundary conditions in life cycle energy assessment (LCEA) analysis in order to promote the incorporation of embodied energy impacts into building energy-efficiency regulations (BEERs). The proposed framework was developed based on an extensive review of 66 studies representing 243 case studies in over 15 countries. The framework consists of six distinctive dimensions, i.e., temporal, physical, methodological, hypothetical, spatial, and functional. These dimensions encapsulate 15 components collectively. The proposed framework possesses two key characteristics; first, its application facilitates defining the conditions of a system boundary within a transparent context. This consequently leads to increasing reliability of obtained LCEA results for decision-making purposes since any particular conditions (e.g., truncation or assumption) considered in establishing the boundaries of a system under study can be revealed. Second, the use of a framework can also provide a meaningful basis for cross comparing cases within a global context. This characteristic can further result in identifying best practices for the design of buildings with low life cycle energy use performance. Furthermore, this paper applies the proposed framework to analyse the LCEA performance of a case study in Adelaide, Australia. Thereafter, the framework is utilised to cross compare the achieved LCEA results with a case study retrieved from literature in order to demonstrate the framework’s capacity for cross comparison. The results indicate the capability of the framework for maintaining transparency in establishing a system boundary in an LCEA analysis, as well as a standardised basis for cross comparing cases. This study also offers recommendations for policy makers in the building sector to incorporate embodied energy into BEERs.