Urban Energy Performance Research Articles

Urban building energy modelling and urban design for sustainable neighbourhood development-A China perspective

Urban design at the neighbourhood scale has profound effects on urban microclimate, and thus on urban buildings energy consumption (in particular heating, cooling and lighting), extent of applicability of passive heating/cooling strategies, indoor/outdoor thermal comfort and street vehicle emissions dispersal (air quality). Previous studies, especially recent explorations in the emerging field of urban building energy modelling (UBEM), suggest clear neighbourhood-scale energy impact from building type, density, layout/orientation and facade/fenestration treatment. The purpose of research is to inform design, but how the research findings in urban building energy inform urban design practice is not straight-forward, in that real-world urban development involves all stakeholders and needs to take environmental, social and economical factors into account, in addition to energy and urban climate. If to support more healthy, comfortable and energy-efficient urban district/neighbourhood is one goal of green neighbourhood development (ND) rating tools, we should investigate possibilities to further and more efficiently integrate findings of UBEM into guidelines and credits system that inform climate-responsive urban design. This paper, based on a review on recent advancement in UBEM, investigates a more comprehensive and systematic prescriptive approach in ND to optimizing urban building energy performance by moderating urban form, fabric and land cover. Although UBEM as a scientific tool is diagnostic in evaluating urban design scenarios on a case basis, prescriptive design guidelines based on good science are suitable and useful for architects in integrating urban building energy issues in practice.

Evaluation of a diagnostic equation for the daily maximum urban heat island intensity and its application to building energy simulations

The reliable estimation of the urban heat island intensity (UHII) within an urban canopy will benefit a number of fields of research such as urban design, public health, and building energy performance. A diagnostic equation for estimating the daily maximum UHII (UHIImax), which is based on routine meteorological data and basic urban properties, was extensively tested with the long-term observations from the metropolis of Nanjing, China. The field measurement has been carried out based on the Local Climate Zone (LCZ) scheme, which is a standardized classification protocol for urban temperature studies. The temperature data set of 658 days collected from six different LCZ classes was used for testing. The results show that the diagnostic equation produced a robust and satisfactory estimation of the daily UHIImax under various weather conditions. The overall performance of the equation for Nanjing, that has a root mean squared error (RMSE) of 0.95 °C and a median absolute error (MEAE) of 0.60 °C, closely approximates its performance for the 14 cities in northwestern Europe (RMSE = 0.91 °C, MEAE = 0.58 °C). The results also imply that the equation has the potential to be applicable to other cities. Another attempt in this study was to develop a method to apply the diagnostic equation to building energy simulations (BES). The hourly heat island intensities were derived from the estimated UHIImax based on the typical diurnal pattern of UHII evolution. An apartment was modeled with the BES program EnergyPlus to examine the validity of the proposed method. Using the modeled and measured temperature data as the inputs in the EnergyPlus simulations, the annual, monthly, and hourly energy demands for cooling and heating were investigated and compared. For all the six LCZ sites except the large low-rise case (LCZ 8), the impacts of the heat island effects at the neighborhood scale on building energy performance were reasonably evaluated with the method. The limitations and perspectives of the equation and its application to BES have also been discussed.

A review of studies on urban energy performance evaluation.

Energy is a foundation for a city to create economic wealth, satisfy people's desires, and achieve benefits. However, the increasing mismatch between energy supply and demand and the worsening of environmental pollution have highlighted the importance of improving urban energy performance, so the number of studies related to urban energy performance evaluation is increasing. Based on describing the authors, numbers, regional sources, and themes of these studies, this paper reviews and analyzes the conceptions, evaluation indicators, influencing factors, evaluation methods, and evaluation systems related to urban energy performance. Most countries have expressed concern about this topic. Researchers in China, Belgium, and the USA have had the most achievements and collaborations. The concept of urban energy performance further extends to a comprehensive performance. It is measured based on an input-output process. In addition to the original evaluation indicators, new desirable outputs and undesirable outputs are included. Industrial structure, energy price, population density, home car ownership, climate factors, Gini coefficient, health expenditure level, and unemployment rate are regarded as influencing factors. Therefore, a new framework of evaluation indicators and influencing factors is constructed. Stochastic frontier analysis (SFA) and data envelopment analysis (DEA) are commonly used to evaluate. With changes in conceptions, evaluation indicators, and influencing factors, the evaluation method should rather focus on measuring multiple input-output variables, determining the evaluation results and the impacts of factors at the same analysis stage, and highlighting policy orientations. As an important management tool, the evaluation system would continue to be studied and developed.

Balancing urban density, energy performance and environmental quality in the Mediterranean: a typological evaluation based on photovoltaic potential

As research on the correlation between urban design and environmental performance is still lacking, the following long-standing question still stands – How far can we densify urban districts without sacrificing their energy balance and indoor environmental quality? This question served as the starting point for a parametric typological study conducted at the block scale in the context of Tel Aviv, with the overall aim of promoting performance driven design of Mediterranean urban environments. Dynamic input parameters included fenestration ratio, aspect ratios and floor area ratios of 5 different building typologies in both office and residential land uses. Environmental outputs included energy cooling loads, spatial daylight autonomy and the monthly average load match between energy demand and photovoltaic energy supply. The courtyard typology was found to achieve the best performance in terms of monthly Load Match, however mostly in residential uses of lower density. Although the high-rise typology offered the best daylight conditions, it recorded the worse performance in terms of energy balance and energy cooling demand. Results demonstrate the potential of a parametric typological workflow to effectively indicate the tradeoffs between single building and urban scale design considerations. This potential could be harnessed to assess the environmental feasibility of net zero energy typologies in Mediterranean climates and will be used for district energy studies as part of future work.

On the relation between urban climate and energy performance of buildings. A three-years experience in Rome, Italy

Climatic conditions strongly affect the energy performance of buildings, and due to the synergy between global climate change and the Urban Heat Island (UHI) effect, the climatic conditions inside and outside the city are highly different. However, weather data collected at airports are commonly used for building energy simulations and these data do not take into account real temperature distribution in cities. Many studies in the literature address the topic but mostly considering only a couple of urban and non-urban stations. In this paper, the urban climate in Rome, Italy, is analysed after monitoring of the air temperature and relative humidity in four selected neighbourhoods and one reference station from October 2014 until September 2017. Rome is characterised by a composite urban pattern and high variability of building types, of which the four selected areas are representative. The heating degree days decrease up to 18% and cooling degree days increase up to 157% in the urban area with respect to the rural reference and the area most affected by the UHI is the city centre. The UHI is more intense in summer than in winter (average increase between 0.7 °C and 1 °C); while the diurnal and nocturnal UHI depends on the season and the neighbourhood. Then, the energy performance of a representative apartment block and a typical office building was computed using the measured data. Regarding the predicted energy performance, comparing the four urban sites and the reference site, the UHI causes a reduction of heating consumption up to 21% in residential building and 18% in the office building. An increase of cooling consumption up to 74% is instead computed for the residential building and up to 53% for the office building.

Urban energy performance monitoring for Smart City decision support environments

In this essay we wish to present an interdisciplinary study carried out in the framework of two Interreg Italy-Austria projects which were intended to design methodologies, simulation tools and decision support instruments to face energy challenges within the overall Smart City concept. The proposed strategy uses a physical model (“City Model”) and an energy behavior model (“City Sensing”) of the urban environment. They were developed using two different approaches: the first is mainly based on analysis of surveys data and the second one on simulations and processing of large-scale datasets. “City Model” and “City Sensing” were then merged to provide an Urban Building Energy Model - that we called “City Energy Model” - integrated with a Participatory Public GIS platform.

An urban energy performance evaluation system and its computer implementation

To improve the urban environment and effectively reflect and promote urban energy performance, an urban energy performance evaluation system was constructed, thereby strengthening urban environmental management capabilities. From the perspectives of internalization and externalization, a framework of evaluation indicators and key factors that determine urban energy performance and explore the reasons for differences in performance was proposed according to established theory and previous studies. Using the improved stochastic frontier analysis method, an urban energy performance evaluation and factor analysis model was built that brings performance evaluation and factor analysis into the same stage for study. According to data obtained for the Chinese provincial capitals from 2004 to 2013, the coefficients of the evaluation indicators and key factors were calculated by the urban energy performance evaluation and factor analysis model. These coefficients were then used to compile the program file. The urban energy performance evaluation system developed in this study was designed in three parts: a database, a distributed component server, and a human-machine interface. Its functions were designed as login, addition, edit, input, calculation, analysis, comparison, inquiry, and export. On the basis of these contents, an urban energy performance evaluation system was developed using Microsoft Visual Studio .NET 2015. The system can effectively reflect the status of and any changes in urban energy performance. Beijing was considered as an example to conduct an empirical study, which further verified the applicability and convenience of this evaluation system.

Study of Urban Energy Performance Assessment and Its Influencing Factors Based on Improved Stochastic Frontier Analysis: A Case Study of Provincial Capitals in China

To improve energy-use sustainability in cities, we proposed a set of urban energy performance assessment indicators and influencing factors based on existing theory and literature. An urban energy performance assessment and influencing factor model was also constructed by the improved stochastic frontier analysis method, and panel data from provincial capitals in China from 2004 to 2013 were considered as an example to carry out an empirical study. Chosen from both endogenous and exogenous perspectives, the urban energy performance assessment indicators and influencing factors take into consideration the capital, labor, energy, urban economic output, urbanization level, population, area, urban climate, and travel selection. Because it considers both random errors and the inefficiency levels of urban productions, the urban energy performance assessment and influencing factor model could reduce the errors caused by two-stage performance assessment and factor analysis, quantify the effects of assessment indicators and influencing factors on urban energy performance, and reflect the actual performance of different cities. Empirical results show that the urban energy performance of provincial capitals in China has been increasing. Chinese provincial capitals also have great potential for energy saving. It was necessary to include energy input as an assessment indicator when evaluating urban energy performance. Population density and urban energy performance showed a negative correlation, but the urbanization rate, temperature index, and household car ownership were positively related to urban energy performance. The urban energy performance of Chinese provincial capitals gradually decreased from east to west. Based on these results, several policy suggestions on urban energy performance development are proposed.

Material Based Urban Modeling: An Approach to Integrate Smart Materials in a Near-Zero Community Design

This article outlines a research agenda to incorporate smart materials into district-scale urban building energy modeling frameworks. This research agenda aims to design eco-communities driven by the near-zero emission objective. Two strategic materials, polyurethane and polycarbonate, were selected for testing. Tests were conducted to evaluate to what extent these smart materials, when embedded in multi-scale systems from construction components, to buildings, to a community, would enhance total urban energy performance. A conceptual framework of holarchies is proposed to articulate subsystems of an urban system. This framework explores the multiple-scale and cross-sectorial relationship of material properties and their building spatial configurations. An experimental test case uses Building Information Modeling (BIM) to construct databases from the various levels of the urban system from M (material), to P (products and building component) and B (building systems). It is then connected to N (neighborhood) by incorporating Urban Energy Building Modeling (UBEM). This connection considers contextual factors such microclimate and landscape features. After conducting the M-P-B-N multi-scale modeling experiment, emerging system properties will be derived and turned into design principles for informing future design decision-making.

Assessment of Urban Energy Performance through Integration of BIM and GIS for Smart City Planning

Smart city has been becoming nowadays a very popular topic that not only in developed countries but also in developing countries. There are variety of definitions for smart city in different fields and regions. Generally, it aims for a sustainable city development through the optimal management of the resources and potential, offering a comprehensively higher quality life to the citizens. The planning of area energy system is one of the most important issues, which is related to the energy generation, the energy consumption by facilities, transportation system, and any other city infrastructures. Especially for Japan, one of the countries facing the complex issues of an aging society, disaster management and energy dependency need a new methodologies for optimal urban energy planning that integrates all information from these sectors. Smart city with highly developed information and communications technology (ICT) is considered as such an important approach. To encourage the smart city concept in Japan, this paper proposes a “GIS-BIM” based urban energy planning system to access the optimal technical and policy solution for readjust city infrastructure beyond the integrated analysis. Firstly, it introduces the concept of Japanese smart city which covers from urban planning to infrastructure. Secondly, the research proposes a GIS-BIM based urban energy planning system including the database construction and analysis by GIS, the optimal energy system design aided by BIM and 3D visualization with user-friendly interface. Finally, center of Tokyo is adopted as a case study, suggesting the potential to access the optimal technical and policy solution.

A Simulation-based Research on Passive District

Abstract This paper is aiming to propose a new design concept named passive district which assists designer to improve district energy efficiency and reduce energy demand by smart urban design without mechanical dynamics method. Furthermore, specific simulation-based experiment is implemented to demonstrate the research methodology on correlation between urban form and energy performance, in which the workflow is summarized as follows: definition of constants and variables, modeling, simulation, data sorting and decision making. This urban modeling integrates the morphological factors together including grid size, floor area ratio, cover ratio, passive zone ratio, surface to volume ratio and so on and compares the energy impact respectively. Particularly a method of multi-disciplinary design optimization (MDO) is applied to analyze how multiple factors affect energy use comprehensively and support scientific decision making. Finally, as conclusion the application potential of passive district is discussed.

Urban Form and Building Energy Performance in Shanghai Neighborhoods

Urban form is considered as two different concepts here: one as geometry and the other as a complex system. This paper uses simulation experiments to test the density and energy performance relationship in nine Shanghai neighborhoods, with the urban form defined as a complex system. The results show a complex pattern. When density is only related to geometry, the density seems to negatively impact building energy use intensity, following the widely perceived conclusion from previously studies. But when density is related to neighborhood typology, which determines many energy-related parameters, the relationship may be totally different. The study suggests that energy performance research of urban form at the neighborhood scale has to consider the historical, social and cultural contexts, which could lead to more comprehensive low energy and low carbon urban policies for Shanghai.

Transforming Urban Morphology and Environmental Perfornances via IMM® The Case of PortoMaravilha in Rio de Janeiro.

AbstractIMM, Integrated Modification Methodology, is a holistic, multiscale and multi-stage, iterative process, applied to urban contexts seen as Complex Adaptive Systems, for improving their metabolism as well as their energy performances. In IMM cities are energy-using systems in their own right and they consume energy in varying level of efficiency. City as CAS is a specific type of complex system with adaptive and resilience ability and its final energy consumption and related performance is different than the sum of its heterogeneous element’s performance.Main headline of the current paper is to focus on how urban morphology is correlated with urban sustainability and energy performance and to demonstrate how an existing urban assessment (Porto Maravilha, in Rio de Janeiro) can be reformed into a lower energy consumption system and a more liveable and sustainable context. This paper wishes to demonstrate how this design methodology can contribute through integrated design optimization to address the challenges of urban growth and environmental issues simultaneously. Actually an Urban modification theory based on an integrated approach can help to sharpen a better comprehension of the different performances of different urban assessment and contribute to climate mitigation and emission reduction, integrating Design Principles with the issue of saving natural resources. In IMM DOPs (design Ordering Principles) are tools/instruments used to arrange the structure of the CAS. The application of these principles affects the CAS’s structure and its performances. In IMM, DOP’s are associated with indicators, a core set of elements used in the process for comparing the characteristic performance of the CAS before and after the transformation occurred.This paper using a specific and challenging case study shows that urban transformation can be performed, retrofitted and monitored with the final goal of achieving a more sustainable arrangement. The authors intended to examine how a local design area located in the dense core of Rio (Porto Maravilha) can affect transformation of the entire CAS (the city of Rio de Janeiro) towards more sustainable development of some of the city’s main concerns, mitigating marginal growth, low performances and a growing pollution as well as promoting social inclusion and a more liveable environment.

Assessing Passive and Active Solar Energy Resources in Cities Using 3D City Models

Many cities today are committed to increasing the energy efficiency of buildings and the fraction of renewables. However, quantitative data on urban energy performance are rarely available during the design stage of new towns or for rehabilitation scenarios of existing cities.Three dimensional city models based on the spatio-semantic data format CityGML offer powerful new methods for the quantitative evaluation of urban energy demand and costs, and simultaneously allow the simulation of renewable energy systems. Such a ‘semantically enriched’ models was used in this work for energy demand diagnostics, refurbishment forecast and renewable supply scenarios.A case study was done using this method in an existing urban quarter in Ludwigsburg/Germany. Based on its three dimensional representation, the photovoltaic potential has been calculated and compared with the electricity demand to establish the photovoltaic fraction. On the thermal side, the passive solar gains were simulated for each building in the city quarter to analyse the solar contribution for heating demand reduction. The simulations were validated with measured gas consumptions. Some rehabilitation scenarios have also been simulated. In such a moderately dense post-war district, the calculated energy savings potential reach in total 65%, equally distributed between heat savings following building envelope refurbishment, and electricity savings due to the installation of PV on the roofs.

Urban form and function as building performance parameters

The climate in cities differs significantly from those found in the surrounding area. These differences results from modifications of the Earth's surface that alters the disposition of “natural energy balance” at a micro-scale and the concentration of activities that results in anthropogenic emissions that change the composition of the atmosphere. These urban effects have distinctive temporal and spatial properties with different impacts on building energy performance depending on their purpose which are rarely accounted for.This paper examines performance implications of a change-of-use (from office to residential) in the context of the UK government's proposal to encourage regeneration and to meet housing needs. However, the diurnal occupation and activity patterns of these uses are distinct. For office buildings, with daytime occupation, focus is on the diurnal heating cycle driven by solar energy gains to which internal energy sources must be added. For residential buildings occupation and activity are primarily associated with the diurnal cooling period, and lower levels of activity that results in a primary heating need. This paper highlights the link between the timing of the urban climate effects, the urban setting and energy performance in a typical city street, where buildings are currently designed for commercial use. It employs London's current and projected climate to simulate heating and cooling demands. By studying the role of urban form and its implications on the suitability of a buildings function we find that a ‘form first’ approach should be considered in the early design stages over the standard ‘fabric first’ approach.

Large-scale renewable energy integration within energy-efficient urban areas: results from three German case studies

Cities consume the vast majority of global energy and, therefore, are major contributors of worldwide CO2 and greenhouse gas emissions. Energy use is chiefly driven by how electricity is produced, how energy is utilized within buildings and how people and materials are moved around a city. Thus, many cities today are committed to increasing the energy efficiency of buildings and the fraction of renewables in energy budgets. However, quantitative data on energy performance and costs are rarely available, making it difficult for cities to effectively evaluate which energy-saving concepts work today and which will work best in the future. This article contributes to the analysis of urban energy performance through a detailed study of three urban case studies. The German case studies cover a medium-sized city (Ludwigsburg) and two city quarters under development (Munich) as well as a recently built (Ostfildern). Although in all cases, solar technologies have the highest potential for decentral renewable supply, the main renewable sources used are biomass and deep geothermal energy, the main reason being today's cost-effectiveness. The Munich case study showed that deep geothermal energy can produce renewable heat at less cost and emissions than biomass or conventional fuels, but there is no renewable contribution to the electricity demand. The 350 ha development will rely on large-scale photovoltaic (PV) integration for a renewable electricity contribution. In the low energy building quarter of Ostfildern, a biomass cogeneration plant covers 80% of the heating and 35% of the electricity consumption. Another 45% of the electricity consumption could be theoretically covered by rooftop PV. The monitoring results show that even on a city quarter scale, it is very difficult to achieve a 100% renewable supply of heating and electricity, if the consumption levels stay at current levels.