Special Issue "Energy Efficient City"

A special issue of Energies (ISSN 1996-1073).

Deadline for manuscript submissions: closed (15 July 2016).

Special Issue Editor

Prof. Dr. Jukka Heinonen
E-Mail Website
Guest Editor
Sustainable Built Environment, Faculty of Civil and Environmental Engineering, University of Iceland, Iceland
Interests: sustainable built environment; life cycle assessments; carbon footprinting; greenhouse gas mitigation; sustainable urban development; built environment life cycle economics
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Special Issue Information

Dear Colleagues,

Cities are known to create wealth and economic growth, and to provide a platform for social activity and knowledge sharing. Already, the majority of the global population resides in cities, and the percentage is expected to further increase. This inevitably leads to increased energy demands, both through the needed infrastructure and real estate developments, and through increased energy demand within cities. At the same time, we are facing an imminent pressure to significantly cut down our energy consumption through all levels of society. This pressure calls upon cities to re-establish themselves as low-energy / low-carbon urban ecosystems.

Recently, a lively academic discourse has emerged on the issue, and this Special Issue concerning the Energy Efficient City seeks to bring the conversation further into the spotlight, and to provide a more profound understanding of the future energy requirements in urban areas. Ideally, this Special Issue will introduce concrete solutions to the grand challenge of energy efficient cities.

We welcome both conceptual and empirical study papers. Papers involving energy simulation and/or modeling are likewise welcomed. The following list of topics is in no way exhaustive, but is intended to inspire the authors’ writing. All topics relevant to the theme of the Energy Efficient City are equally welcomed. Potential topics include:

  • Low-energy/low-carbon city concepts
  • Energy solutions for low-carbon urban areas
  • Low-energy/low-carbon urban ecosystems
  • Energy efficient urban transitions
  • Drivers and barriers for low-energy/low-carbon solutions
  • Energy system changes in cities / urban ecosystems

Papers presenting research results with sound academic contributions and high societal impact potential are particularly welcomed.

Dr. Jukka Heinonen
Guest Editor

Manuscript Submission Information

Manuscripts should be submitted online at www.mdpi.com by registering and logging in to this website. Once you are registered, click here to go to the submission form. Manuscripts can be submitted until the deadline. All papers will be peer-reviewed. Accepted papers will be published continuously in the journal (as soon as accepted) and will be listed together on the special issue website. Research articles, review articles as well as short communications are invited. For planned papers, a title and short abstract (about 100 words) can be sent to the Editorial Office for announcement on this website.

Submitted manuscripts should not have been published previously, nor be under consideration for publication elsewhere (except conference proceedings papers). All manuscripts are thoroughly refereed through a single-blind peer-review process. A guide for authors and other relevant information for submission of manuscripts is available on the Instructions for Authors page. Energies is an international peer-reviewed open access semimonthly journal published by MDPI.

Please visit the Instructions for Authors page before submitting a manuscript. The Article Processing Charge (APC) for publication in this open access journal is 1800 CHF (Swiss Francs). Submitted papers should be well formatted and use good English. Authors may use MDPI's English editing service prior to publication or during author revisions.

Keywords

  • energy efficient city
  • low-carbon city
  • energy-efficiency
  • low-energy building
  • energy system
  • urban ecosystem

Published Papers (12 papers)

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Research

Open AccessArticle
Solar Access Assessment in Dense Urban Environments: The Effect of Intersections in an Urban Canyon
Energies 2016, 9(10), 796; https://doi.org/10.3390/en9100796 - 06 Oct 2016
Cited by 7
Abstract
The urban canyon model has been recurrently used as a basis for many solar access studies. However, its conception as endless structures disregards the effect of street intersections, despite being characteristic elements of urban fabrics. This paper aims to evaluate the impact of [...] Read more.
The urban canyon model has been recurrently used as a basis for many solar access studies. However, its conception as endless structures disregards the effect of street intersections, despite being characteristic elements of urban fabrics. This paper aims to evaluate the impact of street discontinuities on solar access over building façades. The potential of crossings to increase the available radiation has been assessed through computer simulations in dense urban environments in a Mediterranean location. For the cases studied, results show that local effects of an intersection almost disappear beyond a specific distance for each aspect ratio, which can be helpful to determine the suitable level of detail for solar analyses at an urban fabric scale. Full article
(This article belongs to the Special Issue Energy Efficient City)
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Open AccessArticle
Daylight Management in Mediterranean Cities: When Shortage Is Not the Issue
Energies 2016, 9(9), 753; https://doi.org/10.3390/en9090753 - 15 Sep 2016
Cited by 6
Abstract
Natural resources such as daylight and sunlight are highly appreciated in countries with prevailing overcast skies. Taking advantage of this scarce resource contributes to saving energy on artificial lighting. In contrast to northern, southern European cities are distinguished by a large number of [...] Read more.
Natural resources such as daylight and sunlight are highly appreciated in countries with prevailing overcast skies. Taking advantage of this scarce resource contributes to saving energy on artificial lighting. In contrast to northern, southern European cities are distinguished by a large number of days with direct sunlight caused by a propitious climate condition. While it is a positive issue in terms of energy availability, the abundance of it can be counterproductive if management measures are not taken. Apart from the thermal consequences, lighting penetration into buildings causes a great contrast between inside and outside. This is especially critical when the visual system does not have enough time to adapt, as happens at entrance areas. The aim of this study is to analyze the light contrast between these areas and the urban outside in sunny conditions. To attain this objective, light data from five entrance spaces and their contiguous streets were analyzed and measured. The results were divided into three zones in the visual scene, showing an increasing contrast from top to bottom of the visual field. It may be concluded that interventions applied to urban areas and building pavements can improve visual adaptation in the transition zone. Full article
(This article belongs to the Special Issue Energy Efficient City)
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Open AccessArticle
Smart City Services over a Future Internet Platform Based on Internet of Things and Cloud: The Smart Parking Case
Energies 2016, 9(9), 719; https://doi.org/10.3390/en9090719 - 06 Sep 2016
Cited by 17
Abstract
Enhancing the effectiveness of city services and assisting on a more sustainable development of cities are two of the crucial drivers of the smart city concept. This paper portrays a field trial that leverages an internet of things (IoT) platform intended for bringing [...] Read more.
Enhancing the effectiveness of city services and assisting on a more sustainable development of cities are two of the crucial drivers of the smart city concept. This paper portrays a field trial that leverages an internet of things (IoT) platform intended for bringing value to existing and future smart city infrastructures. The paper highlights how IoT creates the basis permitting integration of current vertical city services into an all-encompassing system, which opens new horizons for the progress of the effectiveness and sustainability of our cities. Additionally, the paper describes a field trial on provisioning of real time data about available parking places both indoor and outdoor. The trial has been carried out at Santander’s (Spain) downtown area. The trial takes advantage of both available open data sets as well as of a large-scale IoT infrastructure. The trial is a showcase on how added-value services can be created on top of the proposed architecture. Full article
(This article belongs to the Special Issue Energy Efficient City)
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Open AccessArticle
Methodologies Developed for EcoCity Related Projects: New Borg El Arab, an Egyptian Case Study
Energies 2016, 9(8), 631; https://doi.org/10.3390/en9080631 - 11 Aug 2016
Cited by 4
Abstract
The aim of the methodologies described here is to propose measures and procedures for developing concepts and technological solutions, which are adapted to the local conditions, to build sustainable communities in developing countries and emerging economies. These methodologies are linked to the EcoCity [...] Read more.
The aim of the methodologies described here is to propose measures and procedures for developing concepts and technological solutions, which are adapted to the local conditions, to build sustainable communities in developing countries and emerging economies. These methodologies are linked to the EcoCity framework outlined by VTT Technical Research Centre of Finland Ltd. for sustainable community and neighbourhood regeneration and development. The framework is the result of a long experience in numerous EcoCity related projects, mainly Nordic and European in scope, which has been reformulated in recent years to respond to the local needs in the previously mentioned countries. There is also a particular emphasis on close collaboration with local partners and major stakeholders. In order to illustrate how these methodologies can support EcoCity concept development and implementation, results from a case study in Egypt will be discussed. The referred case study relates to the transformation of New Borg El Arab (NBC), near Alexandria, into an EcoCity. The viability of the idea was explored making use of different methodologies (Roadmap, Feasibility Study, and Residents Energy Survey and Building Consumption Assessment) and considering the Residential, Commercial/Public Facilities, Industrial, Services/Utilities, and Transport sectors. Full article
(This article belongs to the Special Issue Energy Efficient City)
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Open AccessEditor’s ChoiceArticle
Perspectives on Near ZEB Renovation Projects for Residential Buildings: The Spanish Case
Energies 2016, 9(8), 628; https://doi.org/10.3390/en9080628 - 10 Aug 2016
Cited by 15
Abstract
EU regulations are gradually moving towards policies that reduce energy consumption and its environmental impact. To reach this goal, improving energy efficiency in residential buildings is a key action line. The European Parliament adopted the Near Zero-Energy Building (nZEB) as the energy efficiency [...] Read more.
EU regulations are gradually moving towards policies that reduce energy consumption and its environmental impact. To reach this goal, improving energy efficiency in residential buildings is a key action line. The European Parliament adopted the Near Zero-Energy Building (nZEB) as the energy efficiency paradigm through Directive 2010/31/EU, but a common technical and legislative framework for energy renovations is yet to be established. In this paper, the nZEB definition by COHERENO was adopted to evaluate several energy renovation packages in a given building, which is also representative of the Spanish building stock. Global costs are calculated for all of them following EPBD prescriptions. Two economic scenarios are analysed: with entirely private funding and with the current public financial incentives, respectively. The results show the divergence between optimum solutions in terms of costs and of minimum CO2 footprint and maximum energy saving. Moreover, in the absence of enough incentives, some inefficient renovations could achieve a global cost close to the optimal cost. The optimum solution both in terms of energy performance and global costs was carried out and described. Full article
(This article belongs to the Special Issue Energy Efficient City)
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Open AccessEditor’s ChoiceArticle
City Carbon Footprint Networks
Energies 2016, 9(8), 602; https://doi.org/10.3390/en9080602 - 29 Jul 2016
Cited by 30
Abstract
Progressive cities worldwide have demonstrated political leadership by initiating meaningful strategies and actions to tackle climate change. However, the lack of knowledge concerning embodied greenhouse gas (GHG) emissions of cities has hampered effective mitigation. We analyse trans-boundary GHG emission transfers between five Australian [...] Read more.
Progressive cities worldwide have demonstrated political leadership by initiating meaningful strategies and actions to tackle climate change. However, the lack of knowledge concerning embodied greenhouse gas (GHG) emissions of cities has hampered effective mitigation. We analyse trans-boundary GHG emission transfers between five Australian cities and their trading partners, with embodied emission flows broken down into major economic sectors. We examine intercity carbon footprint (CF) networks and disclose a hierarchy of responsibility for emissions between cities and regions. Allocations of emissions to households, businesses and government and the carbon efficiency of expenditure have been analysed to inform mitigation policies. Our findings indicate that final demand in the five largest cities in Australia accounts for more than half of the nation’s CF. City households are responsible for about two thirds of the cities’ CFs; the rest can be attributed to government and business consumption and investment. The city network flows highlight that over half of emissions embodied in imports (EEI) to the five cities occur overseas. However, a hierarchy of GHG emissions reveals that overseas regions also outsource emissions to Australian cities such as Perth. We finally discuss the implications of our findings on carbon neutrality, low-carbon city concepts and strategies and allocation of subnational GHG responsibility. Full article
(This article belongs to the Special Issue Energy Efficient City)
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Open AccessArticle
Energy Optimization in Smart Homes Using Customer Preference and Dynamic Pricing
Energies 2016, 9(8), 593; https://doi.org/10.3390/en9080593 - 27 Jul 2016
Cited by 16
Abstract
In this paper, we present an energy optimization technique to schedule three types of household appliances (user dependent, interactive schedulable and unschedulable) in response to the dynamic behaviours of customers, electricity prices and weather conditions. Our optimization technique schedules household appliances in real [...] Read more.
In this paper, we present an energy optimization technique to schedule three types of household appliances (user dependent, interactive schedulable and unschedulable) in response to the dynamic behaviours of customers, electricity prices and weather conditions. Our optimization technique schedules household appliances in real time to optimally control their energy consumption, such that the electricity bills of end users are reduced while not compromising on user comfort. More specifically, we use the binary multiple knapsack problem formulation technique to design an objective function, which is solved via the constraint optimization technique. Simulation results show that average aggregated energy savings with and without considering the human presence control system are 11.77% and 5.91%, respectively. Full article
(This article belongs to the Special Issue Energy Efficient City)
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Open AccessArticle
Solar Energy as a Form Giver for Future Cities
Energies 2016, 9(7), 544; https://doi.org/10.3390/en9070544 - 14 Jul 2016
Cited by 7
Abstract
Energy is considered as a main influence on urban configurations. However, there is a difficulty on translating the city models based on theoretical renewable energy concepts into practical applications. This study considers the possibility of understanding this future model as a transformation of [...] Read more.
Energy is considered as a main influence on urban configurations. However, there is a difficulty on translating the city models based on theoretical renewable energy concepts into practical applications. This study considers the possibility of understanding this future model as a transformation of the existing urban centres. With this objective, a methodology to intervene in existing cities based on the study of solar access is developed. Therefore, an analysis of solar potential in relation with urban morphology is carried on through a simulation software in l’Eixample, a neighbourhood of Barcelona. The distribution of the sun factor in the different areas of the building blocks envelope displays possible morphological modifications that would facilitate solar energy collection. Consequently, the analytical method presented could be applied to regulate urban interventions with the aim of obtaining more solar energy based cities. Full article
(This article belongs to the Special Issue Energy Efficient City)
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Open AccessArticle
Empirical Operational Energy Analysis of Downtown High-Rise vs. Suburban Low-Rise Lifestyles: A Chicago Case Study
Energies 2016, 9(6), 445; https://doi.org/10.3390/en9060445 - 09 Jun 2016
Cited by 6
Abstract
It is widely accepted that the concentration of people living in high-density city centers offers greater operational energy efficiency and lower greenhouse gas emissions than lower-density expanded suburbs. The prevailing assumption is that lower-density suburbs are dominated by larger low-rise buildings that have [...] Read more.
It is widely accepted that the concentration of people living in high-density city centers offers greater operational energy efficiency and lower greenhouse gas emissions than lower-density expanded suburbs. The prevailing assumption is that lower-density suburbs are dominated by larger low-rise buildings that have higher building energy use requirements and greater per-person automobile travel requirements than high-density city centers dominated by medium- and high-rise buildings located in close proximity to a variety of public transit systems. However, very few studies to date have utilized empirical data at an individual household scale to evaluate differences in the operational energy (OE) footprints for both building and transportation energy end-uses between high-rise urban and low-rise suburban households. Therefore, this work collects empirical data on building and transportation OE consumption by individuals and households living in two economically similar groups: existing high-rise residential buildings in downtown Chicago, IL, USA and existing low-rise residential buildings in suburban Oak Park, IL, USA. Data were collected from over 500 households via an online survey. We considered the following components of residential living: (1) building OE (BOE), which includes electricity and/or natural gas use for all building energy end-uses; and (2) transportation OE (TOE), which includes the OE for multiple modes of transportation (i.e., automobile, bus, subway, regional train, etc.) based on average travel behavior in each location, as well as the OE for supporting transportation infrastructure. We estimate that downtown high-rise living in this sample of residences in Chicago, IL accounts for approximately 427 GJ of primary OE per household per year, on average, which was 14% lower than the average for suburban low-rise living in the Oak Park, IL homes (499 GJ per household per year). However, on a per-person basis, downtown high-rise living accounts for approximately 246 GJ of primary OE per person per year, which was approximately 61% higher than suburban low-rise living (153 GJ per person per year). In both building types, building OE was the single largest contributor to total OE use. This study accurately captured the energy requirements associated with realistic behaviors and lifestyles of occupants of both low-rise suburban and high-rise urban households, and found that building OE dominates the total OE, which suggests that efforts to reduce building OE should be given high priority in building design and management as well as urban planning. Full article
(This article belongs to the Special Issue Energy Efficient City)
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Open AccessArticle
A Methodology for Constructing Marginal Abatement Cost Curves for Climate Action in Cities
Energies 2016, 9(4), 227; https://doi.org/10.3390/en9040227 - 23 Mar 2016
Cited by 8
Abstract
As drivers of climate action, cities are taking measures to reduce greenhouse gas (GHG) emissions, which if left unabated pose a challenge to meeting long-term climate targets. The economics of climate action needs to be at the forefront of climate dialogue to prioritize [...] Read more.
As drivers of climate action, cities are taking measures to reduce greenhouse gas (GHG) emissions, which if left unabated pose a challenge to meeting long-term climate targets. The economics of climate action needs to be at the forefront of climate dialogue to prioritize investments among competing mitigation measures. A marginal abatement cost (MAC) curve is an effective visualization of climate action that initiates a technical and economic discussion of the cost-effectiveness and abatement potential of such actions among local leaders, policy makers, and climate experts. More commonly demonstrated for countries, MAC curves need to be developed for cities because of their heterogeneity, which vary in their urban activities, energy supply, infrastructure stock, and commuting patterns. The methodology for constructing bottom-up MAC curves for cities is presented for technologies that offer fuel switching and/or energy efficiencies, while considering technology lifetimes, city-specific electricity and fuel prices, and emission intensities. Resulting MAC curves are unique to every city, and chart the pathway towards low-carbon growth by prioritizing measures based on cost-effectiveness. A case study of Toronto’s climate targets demonstrates the prioritization of select technologies. Leveraging MAC curves to support climate programs enables cities to strategically invest in financing climate action and designing incentives. Full article
(This article belongs to the Special Issue Energy Efficient City)
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Open AccessArticle
Impact of Urban Morphology on Infiltration-Induced Building Energy Consumption
Energies 2016, 9(3), 177; https://doi.org/10.3390/en9030177 - 09 Mar 2016
Cited by 7
Abstract
External air movement within built neighborhoods is highly dependent on the morphological parameters of buildings and surroundings, including building height and street cavity ratios. In this paper, computational fluid dynamics (CFD) methods were applied to calculate surface pressure distributions on building surfaces for [...] Read more.
External air movement within built neighborhoods is highly dependent on the morphological parameters of buildings and surroundings, including building height and street cavity ratios. In this paper, computational fluid dynamics (CFD) methods were applied to calculate surface pressure distributions on building surfaces for three city models and two wind directions. Pressure differences and air change rates were derived in order to predict the heating load required to cover heat losses caused by air infiltration. The models were based on typical urban layouts for three cities, and were designed of approximately equal built volumes and equal air permeability parameters. Simulations of the three analyzed building layouts resulted in up to 41% differences in air change rates and heat losses caused by air infiltration. In the present study, wind direction did not have a significant impact on the relative difference between the models, however sideward wind direction caused higher air change rates and heat losses for all simulated layouts. Full article
(This article belongs to the Special Issue Energy Efficient City)
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Open AccessArticle
New Aspects to Greenhouse Gas Mitigation Policies for Low Carbon Cities
Energies 2016, 9(3), 128; https://doi.org/10.3390/en9030128 - 25 Feb 2016
Cited by 7
Abstract
Methane (CH4) is an important greenhouse gas emitted by vehicles. This study provides estimates of emissions of this important and often not well characterized greenhouse gas (GHG) emission related to transportation energy use. It aims to assist urban community planners and [...] Read more.
Methane (CH4) is an important greenhouse gas emitted by vehicles. This study provides estimates of emissions of this important and often not well characterized greenhouse gas (GHG) emission related to transportation energy use. It aims to assist urban community planners and policymakers to prioritize and choose implementation strategies for low carbon cities. The paper focuses on emissions of CH4 from vehicles. Unlike emissions of CO2, which are relatively easy to estimate, emissions of CH4 are a function of many complex aspects of combustion dynamics and depend on the type of emission control systems used. In this context, they cannot be derived easily and instead must be determined through the use of published emission factors for each combination of fuel, end-use technology, combustion conditions, and emission control systems. Emissions of CH4 play a significant role with regards to the relative CO2–equivalent GHG emissions of the use of alternative transportation fuels, in comparison with the use of conventional fuels. By analyzing a database based on literature review this study analyzes all the factors affecting the creation of CH4 emissions from different vehicle types. Statistical analysis indicated “r” values ranging from 0.10 to 0.85 for all vehicles. Full article
(This article belongs to the Special Issue Energy Efficient City)
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