Embodied Energy Intensity Research Articles

Uncertainty in the embodied energy assessment of buildings: a case of EWS type low-cost house in India

Studies on embodied energy of buildings often present results as a single-point estimate without considering the variability in input parameters and the uncertainty it poses on results. Uncertainty analysis is useful to improve the reliability of results. This study examines uncertainty in the embodied energy of a single-storey EWS type residential building due to variability in the embodied energy intensity of materials and material wastage factors. Data quality indicator (DQI) based semi-qualitative method is used for modelling the variability in input parameters. Monte Carlo Simulation is used for uncertainty propagation. The building embodied energy is found to vary from 4 to 9 GJ/m2 based on variation in input data. The mean building embodied energy is found to be 6.3 GJ/m2. The embodied energy intensity of materials is found to cause more variation in building embodied energy in comparison with mass of materials. 'Brick’ is identified as the significant key parameter based on the relative contribution to uncertainty and embodied energy at the building level. Cement and rebar are identified as key parameters. The DQI based methodology presented in this study is useful for Life Cycle Assessment practitioners to evaluate uncertainty in the embodied energy assessment of residential buildings.

Partner heterogeneity and driving factors of China's export embodied energy intensity

Although China's energy consumption is very high, foreign demand has become crucial factor affecting China's energy consumption due to exports. A detailed analysis of the embodied energy intensity of China's exports from the demand side could provide valuable insight into promoting China's energy-saving development. This paper explores disparities in the embodied energy intensity of China's exports to different trading partners and the energy supply structure behind these exports. Furthermore, it explores the driving factors of export embodied energy intensity using multiplicative structural decomposition analysis. The results show that China's export embodied energy intensity to developing countries, such as India, is higher than that of European and American countries; however, a convergence trend has emerged over time. Regarding the driving factors influencing changes in export embodied energy intensity over time, the sectoral energy intensity effect plays a pivotal role in promoting its decline, while the production structure and export structure effects change from inhibition to weak promotion. The adjustment of export structure has significant potential for reducing China's export embodied energy intensity, especially in emerging economies. Finally, this paper proposes policy directions for collaborative opening up, energy saving, and emission reduction goals.

Embodied energy intensity of global high energy consumption industries: A case study of the construction industry

Embodied energy intensity of global high energy consumption industries: A case study of the construction industry

Volatile organic compounds emissions embodied in fixed capital formation in China: Gravity movement and decoupling analysis

Volatile organic compounds (VOCs) emissions have increased rapidly in China, but little is known about the characteristics of VOCs emissions embodied in China's fixed capital formation (FCF). We investigate the VOCs emissions embodied in various FCF categories in the economic sectors of 30 Chinese provincial-level regions using the multi-regional input-output (MRIO) method. The gravity theory is combined with the Shapley decomposition method to uncover the gravity movement of embodied VOCs emissions in FCF and regional contributions behind. Besides, the Tapio decoupling index is combined with the logarithmic mean Divisia index (LMDI) method to identify the key drivers of decoupling between embodied VOCs emissions and embodied added value driven by FCF. The results indicate that China's embodied VOCs emissions in FCF increased by 10.9% during 2012–2015 and decreased by 4.2% during 2015–2017. Over 2012–2017, the gravity center of embodied VOCs emissions in gross FCF shifted to the southwest region, with the northwestern and northeastern regions acting as the main engines for the gravity shift. There is a weak decoupling between embodied VOCs emissions and embodied added value in gross FCF. Investment scale and embodied investment efficiency largely inhibit the decoupling, while embodied energy intensity largely promotes the decoupling. Accordingly, we suggest that the northeastern region and northwestern region should be the main targets for VOCs emissions reduction. As such, investment scale, embodied investment efficiency, and embodied emission intensity in FCF should be optimized.

The greenhouse gas rebound effect from increased energy efficiency across China's staple crops

A thorough examination of the uneven greenhouse gas rebound effect (GHG-RE) from increased energy efficiency at crop-specific level can contribute to GHG emissions reduction. This study first evaluated the embodied energy intensities (EEIs) and embodied GHG intensities (EGHGIs) of China's 32 staple crops from 1997 to 2017. Then, a rebound quantization model was introduced to assess crop-specific GHG-REs. The decisive agronomic inputs for uneven crop-specific GHG-REs were further examined. Finally, a structural path analysis (SPA), combined with a structural path betweenness analysis was adopted to identify the high-priority energy paths involved in producing decisive agronomic inputs, in order to improve energy efficiency while curbing uneven crop-specific GHG-REs. The results show that: (1) grain crops generate larger GHG-REs than cash crops. (2) To prevent rapid growth in GHG-REs, six key and six potentially key staple crops must be paid adequate attention. (3) The energy efficiency of plastic film is the primary contributor to crop-specific GHG-REs; agricultural machinery, synthetic fertilizers, and seeds also play important roles. (4) Emphasis should be placed on energy-saving in the production of decisive agronomic inputs. (5) According to the characteristics of high-priority energy paths, different energy-saving measures can be adopted when producing various decisive agronomic inputs.

Contributors and drivers of Chinese energy use and intensity from regional and demand perspectives, 2012-2015-2017

China has been experiencing significant energy use transition accompanied by emphasizing on dual control of energy (e.g. energy consumption and energy intensity). Energy use was expected to present obvious spatial characteristics and differentiated contributions across regions. A systematic energy analysis was carried out to 31 regions (including Tibet) in China for investigating the contributors to national achievements and key drivers of regional energy use. With the help of multi-region input-output model (MRIO) and structural decomposition analysis (SDA) techniques, we found that the aggregate energy use in China has been advanced effectively with a declined increasing total energy consumption and accelerated decreasing total aggregate energy intensity. From regional perspective, Eastern region contributed the most characterized by greater total embodied energy consumption and lower aggregate embodied energy intensity, such as Shandong, Hebei and Jiangsu. From demand perspective, regional energy use has been dramatically determined by investment, consumption and exports in sequence. The changes in regional energy use have been tremendously influenced by the sectoral energy intensity and domestic production structure with differentiated performance across regions. According to additive and multiplicative SDA results, two different regional energy conservation paths, i.e. efficiency- and structure-oriented improvements, were identified for China.

System indeterminacy analysis in the embodied energy network of global construction industries

Energy-sustainable development has a close relationship with the growth of the global economic system, while energy transfer has changed the relationships between sectors and economies. This study measures the system indeterminacy of the linkage network and the network characteristics of the global construction industry from the perspective of embodied energy based on information-based ecological network analysis. Results show that the majority of the studied countries and regions had embodied energy intensities under 20 TJ/million US$ in 2014. The scale of the embodied energy flows expanded almost three-fold in a linear increase over 15 years. The value of the system indeterminacy of the linkage network declined from 2.412 in 2000 to 1.869 in 2014. The findings show that the structure of the linkages between sectors was strengthened by the advance of globalization in the worldwide market, while the uncertainty of the linkage network in the global construction market was gradually eliminated from the perspective of temporal development. Local construction sectors are encouraged to join the global market and expand their trade diversity with more partners to achieve more robust organization.

Analysis of Shanxi Province's energy consumption and intensity using input-output framework (2002–2017)

Shanxi Province is one of the main bases of coal production and consumption in China. We apply the input-output (I–O) framework to study both energy consumption and intensity in Shanxi Province and the factors contributing to their changes at the final demand and sector levels from 2002 to 2017. Among final demand categories, the largest contributors to embodied energy consumption were investment and private consumption. The total final demand effect was responsible for 184.66% of the growth of embodied energy consumption over the study period. The energy intensity effect was the most important factor affecting the change of aggregate embodied energy intensity. At the sector level, construction and mining sectors were the largest contributors to embodied energy consumption. The smelting and pressing of metals, coking, and chemical products sectors had the greatest impact on aggregate embodied energy intensity. The weight of products and services related to residential life on changes in the aggregate embodied energy intensity increased during the study period. Inspired by the analysis results, long-term policies that promote the transformation and development of the regional economy in accordance with the characteristics of the region's resource endowment are recommended.

Environmental evaluation of pump replacement period in water supply systems of buildings

Cost analysis of facility replacement is the common method used in building services facility management nowadays, however, replacement evaluation from the environmental aspect still lacks in literature. This study is the first trial to introduce the environmental evaluation, life cycle assessment technique is adopted, into the replacement period justification of building services facilities, taking water supply pump in buildings as an example. An environmental evaluation model of water supply pump replacement is proposed in this study to minimize the total environmental impact (i.e. energy consumption) of the water supply system, which compares the extra operational energy expenditure in the long-term operation to the pump embodied energy. The literature review is used to obtain the energy intensity data, of mining, metal production, and metal casting, for the determination of pump embodied energy. The results demonstrate that for common pump motor ratings of 1.1–5 kW in water supply systems of buildings, with annual efficiency drop and pump energy intensity that ranges from 0.012 to 0.028 and 18.2–177.6 GJ/t iron and steel respectively, a longer pump replacement period is noticed at the greater energy intensity of pump (the maximum difference of the replacement period can be about 10 years). Besides, higher annual efficiency drop justifies a shorter pump replacement period. It was found that the replacement periods of smaller pumps are more sensitive to the pump energy intensity and annual efficiency drop. Moreover, it was also shown that for pumps with the maximum embodied energy intensity (i.e. 177.6 GJ/t iron and steel), for example, the pump material is stainless steel, the pump replacement periods evaluated on the environmental and economic grounds are comparable. The study results provide an alternative solution of pump replacement period for water supply systems in buildings based on the life cycle environmental assessment of water pump.

Analysis of the Gravity Movement and Decoupling State of China’s CO2 Emission Embodied in Fixed Capital Formation

Investment is an essential engine of economic growth and a major source of China’s CO2 emission. It is therefore crucial to explore the gravity movement and decoupling state of China’s CO2 emission embodied in fixed capital formation (FCF). This study aims to estimate China’s CO2 emissions embodied in various categories of FCF by using input–output tables. The gravity model and Shapley decomposition method are used to explore the gravity movement and regional contributions for China’s CO2 emissions embodied in FCF. Then, the Tapio decoupling model and logarithmic mean Divisia index (LMDI) method are combined to uncover the decoupling relationship between CO2 emissions and economic growth embodied in FCF and the corresponding driving factors. The results show that China’s CO2 emissions embodied in FCF experienced a rapid increase during 2002–2012 and remained almost stable during 2012–2017. The gravity center for CO2 emissions embodied in FCF moved toward northwest during 2002–2015, with the northwestern region and middle Yellow River region being the main engine regions. The relations between CO2 emissions and added values embodied in various categories of FCF were weak decoupling during 2002–2017. Investment scale was the major factor inhibiting the decoupling, while embodied energy intensity was the major factor promoting the decoupling. Finally, several policy recommendations are proposed based on these findings.

Analysis of the embodied energy of construction materials in the life cycle assessment of Hellenic residential buildings

As the operational energy use in new constructions is moving towards nearly zero energy buildings, the embodied energy of buildings is gaining more importance. This work elaborates the importance of embodied energy in Hellenic residential buildings by comparing the primary energy consumption during their life cycle. Field surveys were used to collect relevant data from local manufactures and determine the embodied energy coefficients of popular construction materials. The derived embodied energy intensities (EEI) and the calculated primary energy use intensities (EUI) are then used for benchmarking the buildings’ energy and environmental life cycle performance. The EEI value ranged from 3.2 to 7.1 GJ/m2, compared with annual primary EUI of 0.3 to 3.9 GJ/m2. The initial and recurrent embodied energy of building construction materials over the lifetime of a building can reach up to ~30%. The analysis quantified the time it takes for the operational energy savings resulting from energy conservation measures that are implemented in existing dwellings to recover the embodied energy impact of the new materials or products that are used. For individual measures, the average recovery time ranged from 1 to 6 years, and up to 10 years from more conservative estimates. For a combined scenario it approaches ~2 years or ~3.5 years, respectively.

Life Cycle Energy Assessment (LCEA) Approach: A Prospect for Sustainable Architecture in Developing Countries

Sustainable architecture searches for methods to lessen the adverse environmental burdens of buildings by efficiently and moderately using materials, energy and space. Ensuring sustainable development in multiple dimensions requires an essential factor such as sustainable architectural practice that inculcates assessment framework. Life Cycle Energy Assessment (LCEA) is a key component of Life Cycle Assessment (LCA) in which energy use at different life cycle stage of buildings is the only parameter analysed. In developing countries, defining sustainable architecture and environmental sustainability assessment in buildings remains a herculean task. The aim of the study was to examine the theoretical challenges associated with defining what we mean by calling a building green or sustainable architectural design and a post-positivism viewpoint on sustainability assessment of architectural design. The objectives are to review the criteria for sustainable architecture and conduct an LCEA of an existing residential apartment building in Abakaliki- Nigeria, using process-based Life Cycle Energy Assessment. The embodied energy intensity was found to be high at 6.10GJ/M 2, while cement-based component was 8.8% by mass but accounted for 67.6% of the embodied energy. Consequently, it is imperative to carry out LCEA at the early stage of design and employ strategies to reduce embodied energy instead of focusing only on lessening the operational energy. Environmental and energy efficiency approaches should be prioritized on a life cycle energy basis.

Study on the measurement and the changing trend of the energy use of China’s economic sectors: based on cross-region input-output model

The consumption of fossil energy is the major cause of environmental pollution. Effectively reducing the fossil energy use has important significance for achieving China's green development targets. The premise for reducing fossil energy use is accurately measuring the amount of energy use and identifying the key sectors and links of energy use of China's economic sectors. This paper, by establishing a cross-region input-output model, measured the amount of energy use from the perspective of embodied energy, explored the changing trend of energy use between 2002 and 2015, and identified the key sectors and links of energy use. The results show that the embodied energy intensities of China's economic sectors are generally higher than the world average level, but its changing trend is declining. Although the amount of energy use shows a growth trend, the growth rate manifests a decline process. The key sectors of energy use assemble in the resource sector and heavy industry sector. The key link is intermediate use, but about 80% of embodied energy of intermediate use has been used by downstream sectors. Approximately 76% of the embodied energy of final demand has been used by gross fixed capital formation and urban residents' consumption. China has turned from a net exporter of embodied energy to a net importer since 2012. There is a resource mismatch in China's import and export structure of embodied energy.

Structural path and decomposition analysis of aggregate embodied energy intensities in China, 2012-2017

The dependence of the economic development of a region on its energy consumption is a major challenge for developing countries. The aggregate embodied energy intensity (AEI) based on an input-output framework reflects the interaction between regional economy and energy consumption driven by final demand. Studying the change in AEI from the perspective of sector production and final demand can effectively control the source and trend of energy intensity change in order to control the growth of energy intensity. However, there is a relative lack of studies determining the causes of AEI changes from the perspective of sectors and final demands. This study attempted to identify the influencing factors of AEI changes and establish an AEI-based environmental policy in China. A multiplicative structural decomposition analysis and a structural path analysis were used to study the AEI under conditions of different final demands, sectors, and transmission layers, along with the factors influencing AEI changes in China from 2012 to 2017. Our results indicate that the final demand category of gross fixed capital formation made the largest contribution to AEI changes in 2012 and 2017, and the multiplicative intensity factor significantly inhibited the decrease in AEI. Among the sectors studied, only a few were found to significantly affect the change in AEI, with “S11-Processing of petroleum, coking, and nuclear fuel”, “S12-Chemical industry”, and “S14-Smelting and rolling of metals” being the key sectors that input high-energy-consumption products to other sectors.

Benchmarks for Embodied and Operational Energy Assessment of Hellenic Single-Family Houses

Building energy performance benchmarking increases awareness and enables stakeholders to make better informed decisions for designing, operating, and renovating sustainable buildings. In the era of nearly zero energy buildings, the embodied energy along with operational energy use are essential for evaluating the environmental impacts and building performance throughout their lifecycle. Key metrics and baselines for the embodied energy intensity in representative Hellenic houses are presented in this paper. The method is set up to progressively cover all types of buildings. The lifecycle analysis was performed using the well-established SimaPro software package and the EcoInvent lifecycle inventory database, complemented with national data from short energy audits carried out in Greece. The operational energy intensity was estimated using the national calculation engine for assessing the building’s energy performance and the predictions were adapted to obtain more realistic estimates. The sensitivity analysis for different type of buildings considered 16 case studies, accounting for representative construction practices, locations (climate conditions), system efficiencies, renovation practices, and lifetime of buildings. The results were used to quantify the relative significance of operational and embodied energy, and to estimate the energy recovery time for popular energy conservation and energy efficiency measures. The derived indicators reaffirm the importance of embodied energy in construction materials and systems for new high performing buildings and for renovating existing buildings to nearly zero energy.

Spatial differences in energy performance among four municipalities of China: From both the aggregate and final demand perspectives

City, which consumes the majority of the total energy consumptions, has great influences on the national energy issues. As the widespread spatial differences, a quantitative energy analysis among multi-city allows exploring the targeted and distinguishing energy policy implications at the city level in China. Considering the significant role of final demands, the input-output model and spatial structural decomposition analysis were adopted to evaluate the energy performances and quantify the spatial differences. In 2012, the spatial differences in the energy consumptions were distinct, with the greatest gap between Shanghai and Chongqing, which were mainly driven by the domestic Leontief structure effect and the total final demand effect. In particular, the spatial differences in the embodied energy by net domestic outflow were remarkable. For the relative energy efficiency, Beijing was discovered the best, followed by Tianjin, Shanghai and Chongqing. The spatial differences in their energy intensity were primarily influenced by the energy intensity effect and the domestic Leontief structure effect. In addition, the spatial differences in the aggregate embodied energy intensity by domestic investment were prominent. Inspired by the results, the structure adjustments with respect to the production and final demands and regional cooperation are strongly advised at the city level.

Multiplicative Structural Decomposition Analysis of Spatial Differences in Energy Intensity among G20 Countries

Comparing the spatial differences in the energy intensity of the Group of Twenty (G20) countries and identifying the factors that influence these differences can help the G20 countries formulate targeted policies to achieve energy conservation goals. This study analyzes the spatial differences in the G20 countries’ energy intensity at the aggregate and sectoral levels based on an input–output framework and reveals its driving factors by employing multiplicative structural decomposition analysis, obtaining the sectoral energy intensity, input structure, and final demand structure effects. The results show that: (1) the gap in aggregate energy intensity among the G20 countries tended to converge from 2000 to 2014 with the reducing energy intensity in Russia, India, China, and South Korea having great potential to reduce global energy consumption and improve global energy efficiency; (2) in 2014, the main driving forces for above-average energy intensity was the sectoral energy intensity effect in India, South Korea, and Canada, the input structure effect in Russia and China, and the final demand structure effect in Indonesia; (3) using the average of the G20 countries as a reference, the energy reduction potential of China, Russia, India, South Korea, Indonesia, and Canada is 62.75, 31.94, 21.24, 7.67, 1.47, and 0.81 exajoules (EJ), respectively. The embodied energy consumption decline in these countries was equivalent to 21.78% of the G20’s total energy consumption in 2014; and (4) the most important factor of the high embodied energy intensity of key sectors in India and South Korea is the sectoral energy intensity effect, while for Russia and China, it is the input structure effect.

A Building Life-Cycle Embodied Performance Index—The Relationship between Embodied Energy, Embodied Carbon and Environmental Impact

Knowledge and research tying the environmental impact and embodied energy together is a largely unexplored area in the building industry. The aim of this study is to investigate the practicality of using the ratio between embodied energy and embodied carbon to measure the building’s impact. This study is based on life-cycle assessment and proposes a new measure: life-cycle embodied performance (LCEP), in order to evaluate building performance. In this project, eight buildings located in the same climate zone with similar construction types are studied to test the proposed method. For each case, the embodied energy intensities and embodied carbon coefficients are calculated, and four environmental impact categories are quantified. The following observations can be drawn from the findings: (a) the ozone depletion potential could be used as an indicator to predict the value of LCEP; (b) the use of embodied energy and embodied carbon independently from each other could lead to incomplete assessments; and (c) the exterior wall system is a common significant factor influencing embodied energy and embodied carbon. The results lead to several conclusions: firstly, the proposed LCEP ratio, between embodied energy and embodied carbon, can serve as a genuine indicator of embodied performance. Secondly, environmental impact categories are not dependent on embodied energy, nor embodied carbon. Rather, they are proportional to LCEP. Lastly, among the different building materials studied, metal and concrete express the highest contribution towards embodied energy and embodied carbon.

Structural Change for a Post-Growth Economy: Investigating the Relationship between Embodied Energy Intensity and Labour Productivity

Post-growth economists propose structural changes towards labour-intensive services, such as care or education, to make our economy more sustainable by providing meaningful work and reducing the environmentally damaging production of material goods. Our study investigates the assumption underlying such proposals. Using a multi-regional input-output model we compare the embodied energy intensity and embodied labour productivity across economic sectors in the UK and Germany between 1995 and 2011. We identify five labour-intensive service sectors, which combine low embodied energy intensity with low growth in embodied labour productivity. However, despite their lower embodied energy intensities, our results indicate that large structural changes towards these sectors would only lead to small reductions in energy footprints. Our results also suggest that labour-intensive service sectors in the UK have been characterised by higher rates of price inflation than other sectors. This supports suggestions from the literature that labour-intensive services face challenges from increasing relative prices and costs. We do not find similar results for Germany, which is the result of low overall growth in embodied labour productivity and prices. This highlights that structural change is closely associated with economic growth, which raises the question of how structural changes can be achieved in a non-growing economy.

Water and energy circulation characteristics and their impacts on water stress at the provincial level in China

Water and energy circulate between provinces and sectors through products and services. The multi-scale input–output method can quantify the resources embodied in direct consumption, domestic trade and foreign trade and the resources in intermediate input and final consumption. In this study, this method is used to calculate the embodied water intensity and embodied energy intensity at the provincial level in China. The impacts of interprovincial water and energy transfers on provincial water stress were analyzed with reference to their water stress index. The results show that direct consumption is the main component of the embodied water intensity, with an average proportion of 52.21%. However, differences among provinces are significant, ranging from 14.82 to 80.11%. The embodied energy intensity is mainly reflected in domestic imports, with a national average of 61.01%. Domestic exports (3.69 × 1011 m3), urban household consumption (2.01 × 1011 m3), and gross fixed capital formation (1.49 × 1011 m3) share the largest proportion of final consumption, and they are also the main components in the final consumption of energy. Provincial water and energy transfers do not play major roles in relieving water stress in the net inflow areas but increase water stress in the net outflow areas. Provinces with high embodied water intensity and energy-induced water intensity tend to transfer more water to other provinces, while provinces with low intensity receive more supplies from other areas. Therefore, it is important to focus on improving the water use efficiency in provinces with active trade and high water and energy intensities, pay more attention to the demand side and avoid the continuous expansion of indirect consumption due to excessive restrictions on direct consumption.