Urban Energy Efficiency Research Articles

Can smart city construction improve urban ecological total factor energy efficiency in China? Fresh evidence from generalized synthetic control method

The smart city concept was proposed in the wave of “New Urbanism”. To improve the quality of urbanization, China has launched smart city construction since 2012. Taking 153 cities from China as the research sample, we evaluated the impact of smart city policy (SCP) on urban ecological total factor energy efficiency (ETFEE) using the generalized synthetic control method. The main results are as follows. (1) SCP significantly improves urban ETFEE after controlling the endogeneity and unobserved time-varying confounders, and this conclusion is strongly supported by multiple robustness tests. (2) There is a two-stage mediating mechanism through which SCP functions. Specifically, SCP promotes innovation by enhancing intelligence (including informatization, human capital, and technology), thereby improving urban ETFEE. (3) Public participation and market conditions play moderating effects, and they improve the contribution of SCP on urban ETFEE. (4) For heterogeneity, SCP plays a significant role in eastern cities, large-size cities, non-resource-based cities, and non-old industrial base cities, whereas it has little impact on other cities’ ETFEE. This study provides empirical evidence and policy insights for constructing smart cities in China and even other emerging economies.

The Assessment of Cities Physical Complexity through Urban Energy Consumption

Complex systems analysis is a widely used technique for assessing urban efficiency and sustainability of cities. However, sustainable cities need an effective energy management strategy based on regulations. This research aims to better understand sustainability efficiency of cities by establishing a link between complexity and urban energy consumption. The study demonstrated a technique for estimating physical complexity based on the built environment in an urban region. Accordingly, it applied quantitative measurements of complexity to urban form using empirical methods and information analysis. Consequently, the study evaluated urban complexity and energy consumption in cities using Simpson's variety index and the passive volume ratio. The researcher examined the relationship between complexity and energy use in two districts in Erbil; one is a traditional neighborhood, while the other is part of a modern grid system. The study found that increasing the physical complexity of urban tissue results in reduced urban energy consumption. Thus, there is a chance to comprehend urban energy efficiency with the physical complexity of the city. Consequently, the findings enable decision-makers to evaluate physical complexity using a sophisticated toolset to create more sustainable cities.

Trade policy uncertainty and improvement in energy efficiency: Empirical evidence from prefecture-level cities in China

In the face of the shocks from trade policy uncertainty (TPU), China needs to improve urban energy efficiency (EE) to achieve its “carbon neutrality” goals as scheduled, but the existing literature has no systematic research on this topic. This paper develops and estimates TPU and EE indexes by adopting the Bartik instrument's methods and dynamic slacks-based measure (DSBM). Furthermore, the authors conduct empirical tests on the influencing effect and transmission mechanism of falling TPU on urban EE after the US granted China permanent normal trade relations (PNTR) status in 2001 with a difference-in-difference (DID) model. The results of the empirical study show that urban EE improves by around 1.9% when TPU falls by 1%. A heterogeneity analysis also shows that a falling TPU has a more significant impact on EE in provincial capitals, open cities, “hygienic cities,” highly marketized cities, and cities with a higher share of manufacturing. Falling TPU reduces the cost of foreign capital inflow into China. It drives progress in green technologies, thus improving urban EE by replacing energy factors with innovation-driven non-energy factors. Further, export expansion and export technology complexity significantly raise the stimulating impact of falling TPU on improvement in EE, but growing processing trade impedes this impact. The findings in this study offer a new perspective on estimating the effect of China's policies to respond to global climate change against the shock from TPU and provides new evidence for strengthening global energy cooperation.

Strategies to Improve Urban Energy Efficiency for Urban Resilience

Greenhouse gas (GHG), which is a determining factor in climate change is a result of human activities, namely climate change is human-caused (anthropogenic). Cities, where 60% of the world's population of approximately 7.3 billion living today, are responsible for 60-80% consumption of energy, which is the lifeblood of intense human activities, thus at least 70% of GHG. Nevertheless, cities are the cause of climate change and other global environmental problems, as well as the innovation centres and laboratories to deal with their impact. With climate change becoming more explicit and active in the 21st century, researchers, governments and international institutions question cities’ strength/vulnerability against these problems, especially their energy production and consumption patterns that cause GHG, and they anticipate that urban resilience be the motivating force for urban policies. The widespread and effective use of renewable energy is regarded as an influential tool against climate change. However, this should be endorsed by spatial strategies. In the light of this approach, this study evaluates the urban form, building design and production technologies that are focused on energy efficiency and renewable energy use.

Ushering in a new age of urban energy efficiency and low emission societies

Ushering in a new age of urban energy efficiency and low emission societies

Technical and Energy Efficiency of Urban Logistics in China: Empirical Analysis of 216 Prefecture-Level Cities

With the rapid economic development in China, substantial capital and resources are invested in urban logistics industry leading to quick expansion of the urban logistics. In this paper, the efficiency and energy efficiency of the urban logistics industry in China is measured through a stochastic frontier analysis based on a translog production function for a period of 2009–2017 using a sample of 216 prefecture-level cities. The results lead to several conclusions. (1) Average urban logistics efficiency and energy efficiency scores are at low levels and unbalanced between sample cities over the research period. Cities located in the eastern coastal region have the largest average efficiency scores, the central region has lower scores, and the western region has the lowest. (2) The difference in logistics efficiency between sample cities shows a downward trend for the entire country and eastern region. (3) Technical change plays an important role in promoting urban logistics efficiency. Technical inefficiency is the main cause of the nonefficient frontier of urban logistics. (4) Using the regression analysis, we found that digitalization and road density are positively correlated with the efficiency of urban logistics. Education has a long-term effect on the improvement of the urban logistics efficiency. In contrast, government intervention and environmental regulations are negatively correlated with the efficiency of urban logistics. (5) The effect of most factors on urban logistics efficiency across the sample stratified between eastern, central, and western regions is in line with the estimation results for the whole sample.

A quantitative analysis of the impact of residential cluster layout on building heating energy consumption in cold IIB regions of China

Residential heating energy consumption in China accounts for about 34% of the total building operation energy consumption in the country. The layout pattern of residential clusters is one of the most critical factors affecting building heating energy consumption, yet few scholars have studied the layout of residential clusters in a quantitative way. This paper takes Jinan, a typical city in cold region IIB of China, as an example, to quantify and analyse the residential layout parameters related to heating energy consumption: group layout, building orientation and building spacing; ECOTECT and HTB2 are used to model and simulate the energy consumption of the three types of layout residential groups selected for the study, and the relationship between residential group layout parameters and residential heating energy consumption is analysed based on multiple linear regression analysis. The relationship between residential group layout parameters and residential heating energy consumption was analysed based on multiple linear regression analysis. The study shows that, on the premise of ensuring the same building density, the group layout has the greatest influence on the building energy consumption, and the courtyard layout has lower heating energy consumption compared to the row and staggered layout; on this basis, the influence of building orientation and building spacing on heating energy consumption is discussed. The study shows that increasing the spacing between buildings to meet the daylight spacing will reduce energy consumption by 4% and that a 15° shift to the west will reduce energy consumption by 5%. This result confirms the importance of cluster layout in terms of heating energy consumption and urban energy efficiency in cities in cold regions.

Temporal-Spatial Structure and Influencing Factors of Urban Energy Efficiency in China’s Agglomeration Areas

Energy efficiency has proved to be effective in mitigating greenhouse gas emissions and is significant to carbon neutrality targets. Urban agglomeration is the major engine of urbanization supporting economic growth. To optimizing the spatial exchange structure to improve regional energy efficiency by integrating the total factor energy efficiency model and social network analysis, this study constructs the spatial network of energy efficiency among cities within five major urban agglomerations in China for the period 2011–2018 and investigates their spatial association characteristics. The influencing factors of each spatial network structure are also explored by the quadratic assignment procedure method. The findings show that the spatial association of energy efficiency within each urban agglomeration presents a typical network structure, but with considerable disparity among urban agglomerations. Most cities in the Yangtze River Delta and Pearl River Delta are closely connected with each other, while the surrounding cities in the areas of Beijing-Tianjin-Hebei, Chengyu and the Middle Reaches of the Yangtze River highly depend on their corresponding central cities. The spatial adjacency and GDP per capita determine the urban spatial relationship of the energy efficiency within urban agglomerations. In addition, the spatial correlation of urban energy efficiency in the Beijing-Tianjin-Hebei, Chengyu and Middle Reaches of the Yangtze River areas is also affected by the differences in energy consumption, capital stock, number of labor force and pollutant emission. Some suggestions for improving urban energy efficiency are discussed.

Empirical Analysis and Research on Urban Energy Efficiency Measurement Based on Computer Technology and Total Factor Framework

The utilization rate of energy can reflect the economic development quality and technical level of a country and a region, which directly affects the sustainable economic development. With the rapid progress of China’s urbanization, the total energy consumption is constantly rising, among which the urban energy consumption accounts for more than two thirds of the total energy consumption. Therefore, the urban energy utilization efficiency largely determines the overall level of China’s energy utilization. The results show that the growth rate of energy efficiency and the growth rate of energy use technology efficiency decrease under the constraint of environment. At the same time, due to the neglect of energy emission reduction technologies, the growth rate of technological progress in energy use decreases. As is known to all, carbon dioxide emitted by energy consumption causes a surge in greenhouse gases, leading to global climate anomalies, and China’s carbon dioxide emissions have now surpassed the United States as the number one carbon dioxide emitter. Energy efficiency is an important “energy source”. Drew Warren (1982) regards energy efficiency as the “fifth energy source” alongside coal, oil, natural gas and electricity. Energy efficiency needs to play a major role as a “source of energy” as it can reduce reliance on energy. Based on the analysis of the urban energy research framework, the article of urban energy efficiency measures are divided into broad sense and narrow sense two aspects, combined with domestic and foreign research results, respectively, the energy efficiency at home and abroad to use comparative evaluation index, energy consumption data acquisition method, from two aspects of theory and practical application discusses the applicable scope of different measure methods and its advantages and limitations in the urban energy efficiency analysis, and points out how to enhance the applicability of the overseas related research methods and clear policy boundary scope of relevant research conclusion.

GIS-based urban energy modelling and energy efficiency scenarios using the energy performance certificate database

The EU building stock is 97% not energy efficient and the promotion of energy retrofitting strategies is a key way of reducing energy consumptions and greenhouse gas emission. In order to improve the energy performance of buildings, the European Union released the Energy Performance of Buildings and the Energy Efficiency Directives. The certification of the energy performance of a building is a central element of these Directives to monitor and promote energy performance improvements in buildings, with the aim of increasing their energy efficiency level, thereby reducing greenhouse gas emissions. This work evaluates the energy performance of existing residential buildings using the energy performance certificate database and identifies the more effective retrofitting interventions by applying an urban-scale energy model. The novelty of this study is that a new retrofitting database is created to improve the results of a building energy model at urban scale taking into account the real characteristics of the built environment. The here presented GIS-based monthly engineering model is flexible and easily applicable to different contexts, and was used to investigate energy efficiency scenarios by evaluating their effects of city scale. An urban energy atlas was designed for an Italian city, Turin, as a decision-making platform for policy makers and citizens. This energy platform can give information on energy consumption, production and productivity potential, but also on energy retrofitting scenarios. The results of this work show that it is possible to obtain energy savings for space heating of 79,064 MWh/year for the residential buildings connected to the district heating network in the city of Turin; these interventions refer mainly to thermal insulation of buildings envelope with windows replacement and allow a reduction in greenhouse gas emissions of 12,097 tonCO2eq/year.

Scoping Review of Thermal Comfort Research in Colombia

The analysis of thermal comfort in buildings, energy consumption, and occupant satisfaction is crucial to influencing the architectural design methodologies of the future. However, research in these fields in developing countries is sectorised. Most times, the standards to study and assess thermal comfort such as ASHRAE Standard 55, EN 15251, and ISO 7730 are insufficient and not appropriate for the geographical areas of application. This article presents a scoping review of published work in Colombia, as a representative case study, to highlight the state-of-the-art, research trends, gaps, and potential areas for further development. It examines the amount, origin, extent, and content of research and peer-reviewed documentation over the last decades. The findings allow new insights regarding the preferred models and the evaluation tools that have been used to date and that are recommended to use in the future. It also includes additional information regarding the most and least studied regions, cities, and climates in the country. This work could be of interest for the academic community and policymakers in the areas related to indoor and urban climate management and energy efficiency.

Artificial Intelligence Evolution in Smart Buildings for Energy Efficiency

The emerging concept of smart buildings, which requires the incorporation of sensors and big data (BD) and utilizes artificial intelligence (AI), promises to usher in a new age of urban energy efficiency. By using AI technologies in smart buildings, energy consumption can be reduced through better control, improved reliability, and automation. This paper is an in-depth review of recent studies on the application of artificial intelligence (AI) technologies in smart buildings through the concept of a building management system (BMS) and demand response programs (DRPs). In addition to elaborating on the principles and applications of the AI-based modeling approaches widely used in building energy use prediction, an evaluation framework is introduced and used for assessing the recent research conducted in this field and across the major AI domains, including energy, comfort, design, and maintenance. Finally, the paper includes a discussion on the open challenges and future directions of research on the application of AI in smart buildings.

Housing Refurbishment for Energy Efficiency and Comfort

The housing stock in Vietnam has boomed in the last few decades, especially in urbanised areas. However, the increasing number of housing units did not go along with housing quality, a healthy living environment or a sustainable building stock. Recent legislation only applies to public buildings but not the private housing sector, which accounts for the majority of the building stock. Therefore, this research aimed to contribute to a more sustainable building stock in Vietnam by improving the energy efficiency in new and renovated urban houses. This research started with examining the energy upgrade potential of the existing houses in Vietnam. Both passive and active refurbishment design measures were investigated for the Vietnamese context. Among the measures, a green facade has a large potential in energy saving. Effect of a green facade on thermal and energy performance was tested by conducting a physical experiment on a real tube house in Hanoi. Next, a stepped design strategy was introduced in a student design workshop in Vietnam. The participants were trained to apply sustainable and energy efficient design measures for Vietnamese tube houses. In addition, the vision for designing future tube houses was discussed on several sustainability aspects: urban densification, energy efficiency, circular economy and social interaction. This research is also expected to contribute to the establishing of a future national technical regulation for private housing in Vietnam.

Housing Refurbishment for Energy Efficiency and Comfort

The housing stock in Vietnam has boomed in the last few decades, especially in urbanised areas. However, the increasing number of housing units did not go along with housing quality, a healthy living environment or a sustainable building stock. Recent legislation only applies to public buildings but not the private housing sector, which accounts for the majority of the building stock. Therefore, this research aimed to contribute to a more sustainable building stock in Vietnam by improving the energy efficiency in new and renovated urban houses. This research started with examining the energy upgrade potential of the existing houses in Vietnam. Both passive and active refurbishment design measures were investigated for the Vietnamese context. Among the measures, a green facade has a large potential in energy saving. Effect of a green facade on thermal and energy performance was tested by conducting a physical experiment on a real tube house in Hanoi. Next, a stepped design strategy was introduced in a student design workshop in Vietnam. The participants were trained to apply sustainable and energy efficient design measures for Vietnamese tube houses. In addition, the vision for designing future tube houses was discussed on several sustainability aspects: urban densification, energy efficiency, circular economy and social interaction. This research is also expected to contribute to the establishing of a future national technical regulation for private housing in Vietnam.

Measurement and Analysis of Urban Total Factor Energy Efficiency in China

The improvement of urban energy efficiency is of great significance to reduce carbon emissions and achieve China’s goal of carbon peak in 2030. Taking 266 cities as the research objects, the energy efficiency of each city is measured by Super-SBM model. Then the energy efficiency is decomposed by Malmquist index. The results show that: In 2006, the number of cities in high-efficiency areas is small and high efficiency areas are mostly distributed in the northeast and southeast coastal areas. There was a phenomenon of low efficiency areas agglomeration. But in 2017, the number of high-efficiency cities increased significantly. The number of high-efficiency cities in Northeast China increased, the number of high-efficiency cities in Southeast coastal areas decreased, and the number of high-efficiency cities in Central China increased and showed a phenomenon of agglomeration of high-efficiency areas or relatively high efficiency areas. According to the decomposition of urban energy efficiency, technological progress is the main driving force for the improvement of energy efficiency, and the decline of technical efficiency inhibits the improvement of energy efficiency in various cities.

Impact of natural gas consumption on sub-Saharan Africa's CO2 emissions: Evidence and policy perspective

With huge natural gas(NG) reserves and current low (1%) share of non-hydro renewables in Sub-Saharan Africa (SSA), can natural gas offer SSA a low-carbon energy transition? Employing data from 1980 to 2017, this paper investigates the impact of NG consumption on SSA's CO2 emissions using data-driven nonparametric additive regression(NPAR) which can reveal both linear and nonlinear effects. Augmenting NPAR with translog production function(TPF) estimates of interfuel substitution elasticities and bias technological progress over sample period(advantage of TPF), we further provide evidence of the indirect effect of NG consumption on SSA's CO2 emissions through mechanism analysis. From the empirical results, the linear effect shows NG positively impact CO2 emissions while the nonlinear effect indicates a downward decreasing trend (meaning expansion in NG consumption will gradually lower CO2 emissions). Nonlinearly, urbanization and energy efficiency also show positive “inverted U-Shaped” and “downward slopping” respectively meaning sustainable urban energy and energy efficiency practices improvement can lead to CO2 reduction respectively in SSA. The reducing effect of NG consumption on CO2 (the nonlinear effect) is realized through the enhancement of positive bias technological progress of NG over coal and oil but not merely substitution of coal and oil for NG. Technological progress improvement in NG use will also reduce the positive linear effect of urbanization and energy efficiency on CO2 emissions of SSA. Oil is more likely to be substituted for NG than that of coal in SSA. The scenario analysis shows a total of 6.9%, 7.6% and 8.3% of energy conservation is realized in 2022, 2026 and 2030 with a corresponding CO2 reduction of 18.7%, 20.7% and 22.9% respectively for a continuous 10% investment in NG. Institutional, market-oriented and technology challenges hinder NG development among major producers in SSA. Based on the results, several policy measures are put forward to promote SSA's low-carbon energy transition.

Evaluation method for urban renewable energy utilisation efficiency based on DEA model

In order to overcome the low accuracy of urban energy efficiency evaluation, a method of urban renewable energy efficiency evaluation based on DEA model was proposed. Based on the principles of representativeness, comparability, feasibility and DPSIR model, the evaluation index system of urban renewable energy efficiency was constructed. The Analytic Hierarchy Process (AHP) is introduced to screen the indicators. The primary indicators are mainly composed of economy, physics and synthesis. The secondary index mainly consists of elastic coefficient of energy consumption and comprehensive utilisation rate of waste. Based on the evaluation index system, DEA is introduced to construct the evaluation model by taking the city as a decision-making unit DMU, so as to realise the evaluation of urban renewable energy use efficiency. The experimental results show that the evaluation results of the proposed method are closer to the actual situation than the literature results, and the fitting degree is more than 90%.

Is the High Quality Baukultur a Monkey Wrench in the Global Climate Challenges?

Abstract The EU 2030 climate package calls for raising energy efficiency, increasing usage of RES and decreasing the carbon footprint. There are stringent requirements for new buildings, but the energy efficiency potential in the existing building stock is still not fully explored. The latest trend in urban energy efficiency is the Positive Energy Block (PEB) strategies for new developments. It includes raising building energy efficiency, optimizing energy flow and implementing renewable energy sources (RES). Transforming all existing blocks in a city centre to a PEB would radically change the pattern of energy supply and consumption. European cities have historic centres with great architectural and cultural value. Any urban regeneration strategies must respect and preserve historic values. This paper describes double multi-criteria analysis evaluating urban blocks from both the energy efficiency and cultural heritage perspective with the goal to select the sample block for a “Smart urban regeneration – transition to the Positive Energy Block” case study. Proposed criteria for multi-criteria analysis to evaluate cultural heritage, liveability and energy efficiency potential describes specific qualities of the urban block. The obtained results show that blocks with higher cultural value show less energy efficiency potential and vice versa. It is recommended to apply cultural value and liveability qualities in the Smart urban regeneration process to those blocks with high energy efficiency potential.

Explaining Spatial Variations in Residential Energy Usage Intensity in Chicago: The Role of Urban Form and Geomorphometry

Understanding the spatial pattern of energy consumption within buildings is essential to urban energy planning and management. This study explores the spatial complexity of residential energy usage intensity, with a focus on urban form and geomorphometry attributes. Using spatial regression models, we find that while vegetation and isolation have more local impact on energy intensity, urban porosity and roughness length have consistent spillover effects on building electricity usage intensity in Chicago. In addition, these relationships are seasonally varied. The results highlight the importance of spatially explicit policies and clear urban design and form frameworks for improving urban energy efficiency.

A Research on Energy Efficiency Measurement of Urban Rail Transit Based on Dynamic DEA Model

With the accelerated construction process of urban rail transit, it brings much consumption of energy. While the energy of our country is not enough, it is of great meaning to improve the energy efficiency for the energy saving of the urban rail transit industry. In this thesis, data envelopment analysis (DEA) is used to construct the dynamic DEA model of energy input and output in different periods of subway lines, and quantitative analysis of urban rail transit energy efficiency. Based on the data of energy input and output in different periods of Wuhan Metro’s existing operation lines, this thesis analyzes the utilization status of Wuhan Metro energy from three aspects: technical efficiency, scale efficiency and comprehensive efficiency, gaining the energy efficiency, and then measuring the dynamic energy efficiency through taking into time consideration. And on the basic of it, combining the slack variable adjustment values of each decision-making unit, it uses the difference between the adjustment value of the slack variable and the target value to identify the main influencing factors, and then providing an effective improvement strategy for the improvement of energy efficiency of different lines of Wuhan Metro.