Dissertations / Theses on the topic 'Urban Energy Modelling (UEM)'

Sustainability contests represent a fundamental challenge to traditional urban development practices and concepts. Reducing energy consumption and greenhouse gas emissions from urban infrastructure and building stock, towards low-carbon cities requires a supportive planning process. In this regard, the use of appropriate tools and methods for addressing complex interactions of Urban Energy Planning (UEP) processes is needed. In particular, the problem of building stock energy consumption in the urban environment is crucial. A major aim of this research is to model energy consumption patterns based on bottom-up statistical-engineering combination methods. These methods evaluate the current status of energy consumption and different future energy saving scenarios to promote sustainable urban planning. However, the choice among urban energy planning scenarios is extensively based on multi-actors and multi-criteria aspects. Therefore, to anchor such a sustainable urban planning, a wider societal consensus building with an earnest and active engagement of relevant stakeholders in the city is essential. For this purpose, stakeholder-oriented approach plays a key role in implementing the effective strategies for urban and regional adaptation. The research, therefore, is also dealing with the integration of participative decisional processes of urban energy planning by organizing different focus groups involving real stakeholders. This fact can help to assess, over a short/long term period, the mix of measures by analyzing meaningful scenarios focused on energy consumptions, environmental impacts, economic and social aspects. The result is the development of a new Multi-Criteria Spatial Decision Support System (MC-SDSS), which is an interactive energetic plug-in in GIS environment using CommunityViz. This tool has been applied to a demonstrator case-study, related to a medium-sized city of the metropolitan area of Turin. However, the methodology used for delivering the tool can be applied to other contexts due to its flexibility. The new MC-SDSS is intended to facilitate the decisional process for stakeholders who can ask “what-if” questions and visualize “if-then” scenarios in a real-time. Moreover, it can explore a range of possible futures for assisting urban planners, policymakers and built environment stakeholders in their efforts to plan, design and manage low-carbon cities. This thesis is part of a national Smart City & Communities project, named “EEB-Zero Energy Buildings in Smart Urban Districts” (www.smartcommunitiestech.it).

In summary, this thesis proposes to address the problem of simulating physical effects in large urban environments through the use of procedural rules and Level-of-Detail techniques, in order to reduce the computational complexity of these simulations, but at the same time trying to maintain an acceptable accuracy in the results for decision-making. The final results show that it is possible to obtain credible results in different study cases, all with reasonable calculation times, with the user being able to adjust the parameters to obtain the desired balance between accuracy and calculation time.
En resum, aquesta tesi proposa abordar el problema de simular els efectes físics en grans entorns urbans mitjançant l'ús de regles procedimentals i tècniques de nivell de detall, per tal de reduir la complexitat computacional d'aquestes simulacions, però tractant alhora de mantenir una precisió acceptable en els resultats per a la presa de decisions. Els resultats finals mostren que és possible obtenir resultats creïbles en diferents casos d'estudi, tots amb temps de càlcul raonables, amb l'usuari ajustant els paràmetres per obtenir l'equilibri desitjat entre precisió i temps de càlcul.

Refrigeration, air conditioning and heat pump (RACHP) systems currently account for nearly 20% of UK grid electricity use and over 7% of all UK greenhouse gas emissions. This research project has investigated the sources and levels of emissions from RACHP systems and how the cooling (and heating) energy and emissions from buildings might be reduced by optimizing the building’s design, construction and operation. Analysis of data from site surveys and maintenance logs confirmed that leakage of refrigerant can be a significant contributor to total RACHP emissions. TEWI (total equivalent warming impact) analyses showed that for RACHP systems with high GWP (global warming potential) refrigerants and annual leak rates of 10% or more, direct emissions from refrigerant leakage can exceed the indirect emissions associated with energy use. However, for heat pump and air conditioning systems, with typical leak rates of below 3%, using low GWP refrigerants (GWP = 500 or less), the direct emissions do not make a significant contribution to building emissions. A new dynamic energy balance model and Excel based tool were developed to help improve the understanding of building energy use and emissions. The tool can be used to predict the sensitivity to different building design concepts, features and operation and the parameters of the installed RACHP plant. Results for an office building suggest that the building fabric (with the exception of the glazing) is not necessarily a key factor influencing the total energy use and emissions. However, relatively simple measures to reduce electricity use and to reduce solar gain could each reduce building emissions by 10% or more. Results for a dwelling built to 2006 Building Regulations demonstrated an overheating risk in summer, even with mechanical ventilation, but adding a 2 kW air conditioning unit could prevent overheating, with lower energy use and emissions than a similar dwelling incorporating mechanical ventilation. Climate change simulations for the year 2080 predicted a net increase in energy demand and emissions of about 5% for the office building (mainly associated with the use of grid electricity), implying that the grid carbon factor is likely to be a key determinant of future emissions from such buildings. For dwellings without mechanical ventilation or air conditioning, internal temperatures might rise as high as 40°C in summer months, but a small air conditioning unit could maintain temperatures below 25°C with no increase in total energy use and emissions compared with the present day. For a grid electricity carbon factor reduction of 80%, total emissions for the simulated office building would fall by about 70% and for the dwelling by about 50%.

The energy consumption and greenhouse gas (GHG) emissions associated with urban water systems have come under scrutiny in recent times, as a result of increasing interest in climate change, to which urban water systems are particularly vulnerable. The approach most commonly taken previously to modelling these results has been to consider various urban water system components in great detail, but in isolation from the rest of the system. This piecewise approach is suboptimal, since it systematically fails to reveal the relative importance of the energy consumption and GHG emissions associated with each system component in the context of the entire urban water system. Hence, it was determined that a new approach to modelling the energy consumption and GHG emissions associated with urban water systems was necessary. It was further determined that the value derived from such a model would be greatly enhanced if it could also model the water consumption and wastewater generation associated with each system component, such that integrated policies could be developed, aimed at minimising water consumption, wastewater generation, energy consumption and GHG emissions concurrently. Hence, the following research question was posed: How should the relationships between the water consumption, wastewater generation, energy consumption and GHG emissions associated with the operation of urban water systems be modelled such that the impact of various changes to the system configuration made at different spatial scales can be determined within the context of the entire system? In this research project, life cycle assessment ideas were employed to develop such a new modelling methodology. Initially, the approach was developed at the building-scale, such that the end uses of water present in a selected building and any associated appliances could be modelled, along with the fraction of the citywide water supply and wastewater systems directly associated with providing services to that building. This vast breadth of scope was delivered by considering only the operational life cycle stage of each urban water system component, excluding both the pre- and post-operational life cycle stages of the associated infrastructure. The value of this pilot model was illustrated by several case studies, focused on residential buildings connected to the centralised water supply and wastewater systems in Melbourne, Australia. Later, the approach was extended to the city-scale by using probabilistic distributions of each input parameter, such that all of the end uses of water present in a city, and all of the associated building-scale appliances could be modelled, along with the associated complete water supply and wastewater systems. The value of this city-scale model was illustrated by applying it to model a hypothetical case study city, resembling Melbourne, Australia in many ways. Due to a lack of data, this application was limited to the residential sector of the case study city, along with the fraction of the citywide water supply and wastewater systems directly associated with providing services to that sector. The results generated by the pilot and city-scale models showed that the new modelling methodology could be employed at a wide range of scales to assess the relative importance of each modelled urban water system component in terms of the specified results. Importantly, the high resolution of those results enabled the identification of the underlying causes of the relative importance of each urban water system component, such that efficient and effective approaches to reducing each result for each system component could be developed. Interestingly, for the specific case studies investigated, it was revealed that some commonly neglected system components were actually extremely important, such as domestic hot water services, a trend found to be largely driven by hot water consumption in showers.

The 196 parties attending the conference on climate changes (COP21) in Paris highlighted the need of reducing greenhouse gas emissions [1]. In this regard, in the last years, many countries are providing incentives to promote the deployment of low-carbon and sustainable energy production technologies [2], generation such as Photovoltaic (PV) Systems. The International Energy Agency reports that [3] installation of Renewable Energy Sources (RES), Distributed Generation (DG) and an optimization of consumption with a smart use of energy is required in our cities in order to achieve the goal of reducing green house emissions. ICT technologies, in particular the Internet of Things, enable the possibility of controlling and optimizing consumption [4] hence increasing energy efficiency. The transition from centralized production system to a distributed generation, that can be based on renewable or on conventional sources, substantially modifies the operation of electricity networks: the direction of power flows in the MV lines and even in high voltage/medium voltage (HV/MV) transformers can be reversed, voltage profiles are modified, fault management is affected [5, 6], etc. For all these reasons, distribution networks need to become Smart and new control strategies, algorithms and technologies need to be tested and validated before their implementation and installation in real systems. In this context, ICT play a crucial role in both planning expansion and monitoring operation of distributed energy sources. The crucial roles of ICT and the emerging Internet-of-Things (IoT) are highlighted by the spread diffusion of heterogeneous and pervasive sensors in our houses, district and cities. IoT devices and sensors allow to collect large amounts of energy related data capable of describing the consumption behaviours of the citizens. Hence, the increasing presence of sensors calls for the development of distributed software infrastructure for exploiting such IoT devices for data management and collection. Furthermore, IoT devices enables the possibility of monitoring devices and system in order to develop models for the simulation and optimization on energy process. This Thesis presents a distributed infrastructure, called SMIRSE, for modelling and simulating renewable energy sources and smart policies integration in urban districts. SMIRSE is implemented as a modular infrastructure build with a micro-services approach that exploits Internet of Things communication protocols. This approach enabled interoperability between hardware and software components of the SMIRSE platform and at the mean time its modularity, extendability and scalability. Its modularity allowed the interfacing and integration between dedicated Real-time Grid Simulator, software simulation modules and real-time data in order to model the grid behavior. New modeling and simulation tools for i) Solar energy simulation, with a focus on Photovoltaic systems; ii) Integration of RES and smart policies with the distribution grid; iii) Characterization of thermal performance of Buildings and power consumption prediction; and iv) Buildings indoor temperature simulation and monitoring, have been designed, developed and integrated upon the backbone of the microservices-based infrastructure. The main advantage of the SMIRSE infrastructure is its capability in creating different scenarios for Multi-Energy-System simulation with a minimum effort. Examples of scenarios were SMIRSE can be used are: i) Installation of Renewable Energy Sources, ii) Grid reconfiguration, iii) Demand Response and iv) Demand Side Management. In addition, the proposed infrastructure enables to study the interoperability among different use-cases in a plug-play fashion. Finally, the proposed solution can integrate Smart Metering Architecture to exploit (near-) real-time data collected from the field to co-simulate different smart energy strategies with real information. The main contribution of this study is the design and development of a distributed infrastructure for energy system simulation that exploits state of the art ICT technology. Its worthnothing to say that such ICT technology have been customized for the purpose of developing energy system co-simulation infrastructure.

Influenced by environmental concerns and rapid urbanisation, cities are changing the way they historically have produced, distributed and consumed energy. In the next decades, cities will have to increasingly adapt their energy infrastructure if new low carbon and smart technologies are to be effectively integrated. In this context, advanced planning tools can become crucial to successfully design these future urban energy systems. However, it is not only important to analyse how urban energy infrastructure will look like in the future, but also how they will be operated. Advanced energy management strategies can increase the operational efficiency, therefore reducing energy consumption, CO2 emissions, operational costs and network investments. However, the design and analysis of these energy management strategies are difficult to perform at an urban scale considering the spatial and temporal resolution and the diversity in users energy requirements. This thesis proposes a novel integrated modelling framework to analyse flexible transport and heating energy demand and assess different demand-side management strategies in urban energy systems. With a combination of agent-based simulation and multi-objective optimisation models, this framework is tested using two case studies. The first one focuses on transport electrification and the integration of electric vehicles through smart charging strategies in an urban area in London, UK. The results of this analysis show that final consumer costs and carbon emissions reductions (compared to a base case) are in the range of 4.3-45.0% and 2.8-3.9% respectively in a daily basis, depending on the type of tariff and electricity generation mix considered. These reductions consider a control strategy where the peak demand is constrained so the capacity of the system is not affected. In the second case study, focused on heat electrification, the coordination of a group of heat pumps is analysed, using different scheduling strategies. In this case, final consumer costs and carbon emissions can be reduced in the range of 4-41% and 0.02-0.7% respectively on a daily basis. In this case, peak demand can be reduced in the range of 51-62% with respect to the baseline. These case studies highlight the importance of the spatial and temporal characterisation of the energy demand, and the level of flexibility users can provide to the system when considering a heterogeneous set of users with different technologies, energy requirements and behaviours. In both studies, trade-offs between the environmental and economic performance of demand-side management strategies are assessed using a multi-objective optimisation approach. Finally, further applications of the integrated modelling framework are described to highlight its potential as a decision-making support tool in sustainable and smart urban energy systems.

Renewable energy sources, in form of solar power, is a growing source of energy. Not only at an industry level but also at a commercial level. Grid-connected, building-applied solar power has increased rapidly and as the implementation of solar energy grows, so does the importance of being able to evaluate locations that are of interest of installations with respect to its potential production and its impact on the electrical grid. In this thesis the energy production for different future scenarios is modelled for BAPV (Building Applied Photovoltaics) in Uppsala and Herrljunga. This is done by using calculation and simulation programs called MATLAB and ArcGIS. The results regarding Uppsala, are used in a report by BEESG (Built Environment Energy Systems Group) at Uppsala University to the Swedish energy agency. The grid impact of installing extensive solar power as concentrated and dispersed in Herrljunga are simulated and evaluated. Both authors has during the process been equally involved in all parts of the thesis in order to get a thorough understanding of the project as a whole. This due to the fact that the different parts of the thesis were dependent of each other (the second part could not be finished until the first were completed etc).

Climate change projections estimate a rise of approximately 3 °C by the 2080‘s for most of the UK (under a medium emissions scenario at 50% probability level, 1961-1990 baseline). Warming is of particular concern for urban areas due to the issues of urban densification and the Urban Heat Island (UHI) effect. To combat warming, one adaptation strategy that has been suggested for urban areas is increasing the proportion of greenspace, such as parks, gardens, street tree plantings, and green roofs. While a number of studies have investigated the cooling effect of greenspace in terms of park size, proximity to a park, or area covered by tree canopy, little is yet known about the specific types of greenspace that contribute to its cooling effectiveness and how this relates to building energy demand. This thesis employs an interdisciplinary approach to model fine-scale changes to greenspace for a temperate northern UK city, linking the resulting microclimate changes to building energy consumption in commercial buildings. Using the urban microclimate model ENVI-met, two study areas (one urban one suburban) were modelled with seven different greenspace scenarios (a base case representing current field conditions, +5% new trees, +5% mature trees, +5% hedges, addition of a green roof on the largest building, changing all current greenspace to grass only, and changing all current greenspace to asphalt only) for a summer day in July 2010. The models were calibrated based on measured air temperature data and then analysed for microclimate changes due to each greenspace scenario. Both the modelled and measured microclimate data were then used to inform a series of building energy models using IES-VE 2012 for three commercial building types, estimating summer cooling and winter heating trade-offs due to greenspace effects. For the most effective scenario of adding 5% mature trees to the urban case study, the microclimate modelling estimates a maximum hourly air temperature reduction of nearly 0.7 °C at 5 pm and surface temperature reductions up to 1.7 °C at 3 pm. In the suburban case study, a 5% increase in mature deciduous trees can reduce mean hourly surface temperatures by 1 °C between 10 am and 5 pm, while the worst case scenario of replacing all current vegetation (20% of the study area) with asphalt results in increased air temperature of 3.2 °C at mid-day. The building energy modelling estimates a reduction of 2.7% in July chiller energy due to the combination of reduced UHI peak hours and eight additional trees (four on the north side and four on the south side) of a three-storey shallow plan building. These energy savings increase to 4.8% under a three-day period of peak UHI conditions. While winter boiler energy usage shows large reductions for a building in an urban location with a low proportion of greenspace (as compared to a suburban location), this benefit is marginal when analysed in terms of carbon trade-offs between summer cooling and winter heating requirements.

The objective of this work is to study the urban climate, mainly by focusing on urban temperature trends. The specific focus is to understand the reasons of increase in minimum temperature through observational and modelling techniques. For this purpose, the temperatures data from 1950 to 2004 measured on several meteorological stations of Pakistan is studied and analyzed. Daily averaged annual and seasonal minimum (Tmin) and maximum (Tmax) temperature data of 37 meteorological observatories of Pakistan (17 urban, 7 town and 13 rural) from 1950 to 2004 is first homogenized and then analyzed. The results show that after 1980s Tmin and Tmax increase faster than the period before 1980s at urban areas. During 1980-2004, the increase in Tmin at major urban stations is observed higher than the smaller towns and rural stations. To understand, the effect of the size of the city, changing land use and the building height on the evolution of minimum and maximum temperatures in urban areas has been studied by using the FVM (Finite Volume Model) model and the simulations are run for three days starting at 00:00 (GMT) on 19th day of each month and ending at 00:00 (GMT) on 22nd day of each month. For each month, 48 possible combinations of simulation scenarios are run (4*4*3) and in total, 576 simulations (48*12) are run for a year. The main results show that Tmin and Tmax increase when urban fraction u, city size r and building height h increase. But it is noticed that Tmax increases more than the Tmin when u increases, Tmin increases more than the Tmax when r increases and Tmin increases more than the Tmax when h increases. Among all urban factors (urban fraction u, city size r and building's height h), city size is the major factor that mainly contributes to increase the minimum temperature more than the maximum temperature in urban areas.

Urban and building energy simulation models are usually driven by typical meteorological year (TMY) weather data often in a TMY2 or EnergyPlus Weather data file (EPW) format. In addition, currently, in many countries, weather data files with a TMY format are used for building regulation compliance calculations. However, the locations where these historical datasets were collected (usually airports) generally do not represent the local, site specific micro-climates that cities develop. In this thesis, a humid sub-tropical climate context has been considered. An idealised “urban unit model” of 250m radius is presented as a method of adapting commonly available weather data files to the local micro-climate. This idealised “urban unit model” is based on the main thermal and morphological characteristics of nine sites with residential / institutional (university) use in Hangzhou, China. The area of the urban unit was determined by the region of influence on the air temperature signal at the centre of the unit. Air temperature and relative humidity were monitored and the characteristics of the surroundings assessed (e.g. green-space, blue-space, built form). The “urban unit model” was then implemented into micro-climatic simulations using a Computational Fluid Dynamics – Surface Energy Balance analysis tool (ENVI-met, Version 4). The “urban unit model” approach used here delivered results with performance evaluation indices comparable to previously published work (for air temperature; RMSE < 1, index of agreement d > 0.9). The micro-climatic simulation results were then used to adapt the air temperature of the TMY file for Hangzhou to represent the local, site specific morphology under three different weather forcing cases, (i.e. cloudy/rainy weather ( Group 1), clear sky, average weather conditions (Group 2) and clear sky, hot weather (Group 3)). Following model validation, two scenarios (domestic and non-domestic building use) were developed to assess building heating and cooling loads against the business as usual case of using typical meteorological year data files. A dynamic thermal simulation tool (TRNSYS) was used to calculate the heating and cooling load demand change in a domestic and a non-domestic building scenario. The heating and cooling loads calculated with the adapted TMY-UWP file show that in both scenarios there is an increase by approximately 20% of the cooling load and a 20% decrease of the heating load. If typical coefficient of performance (COP) values for a reversible air-conditioning system are 2.0 for heating and 3.5 for cooling then the total electricity consumption estimated with the use of the “urbanised” TMY-UWP file will be decreased by 11% in comparison with the “business as usual” (i.e. reference TMY) case. However, this assumes a cooling set-point of 26oC. If a lower set-point is used the predicted energy savings will be lost. Overall, it was found that the proposed method is appropriate for urban and building energy performance simulations in humid sub-tropical climate cities such as Hangzhou, addressing some of the shortfalls (i.e. the representation of the urban micro-climate) of current simulation weather data sets such as the TMY.

This paper describes a methodology to assess the energy performance of residential buildings starting from the semantic 3D city model of Vienna. Space heating, domestic hot water and electricity demand are taken into account. The paper deals with aspects related to urban data modelling, with particular attention to the energy-related topics, and with issues related to interactive data exploration/visualisation and management from a plugin-free web-browser, e.g. based on Cesium, a WebGL virtual globe and map engine. While providing references to existing previous works, only some general and introductory information is given about the data collection, harmonisation and integration process necessary to create the CityGML-based 3D city model, which serves as the central information hub for the different applications developed and described more in detail in this paper. The work aims, among the rest, at developing urban decision making and operational optimisation software tools to minimise non-renewable energy use in cities. The results obtained so far, as well as some comments about their quality and limitations, are presented, together with the discussion regarding the next steps and some planned improvements.

This thesis investigates the impact of physical planning policy on combined transport and dwelling-related energy use by households. Separate analyses and reviews are conducted into dwelling-related and transport-related energy use by households, before a model is developed to investigate the city-wide implications of different land-use scenarios in Sydney, Australia. The analysis of household energy use in Chapter 3 suggests that medium density housing (i.e. lose-rise apartments, townhouses, and terraces) is likely to result in the lowest per-capita energy use, while also allowing for sufficient densities to make frequent public transport service viable. The analysis of transport energy in Chapter 4 confirms that increasing urban density is associated with decreased car ownership and use, independent of other factors. However, land use changes alone are likely to result in modest changes to travel behaviour. The results of the scenario modelling in Chapters 7-9 support the view that changes to land use alone can reduce household energy consumption, but the changes, even over a long time period (25 years) are small (~0-10%) for all but the most extreme land-use policies. Instead, a coordinated (land-use/transport and other policy levers) approach is much more effective. The results confirm that it is transport energy that is most sensitive to planning policy, but that a combined consideration of dwelling-related and transport-related energy use is still useful. The micro-simulation model developed to assess the impact of different land-use planning scenarios allows the establishment of a lower-bound estimate of the effect that housing policy has on household energy use, assuming ‘business as usual’ transport policy, household behaviour, and technology.

Increasing demands for energy and water from a growing urban population challenges resource availability and infrastructure capacity in cities worldwide. Planning for infrastructure systems development to meet growing demands has traditionally been done separately, not regarding that these systems are in many aspects interlinked. New York City has well developed systems for supplying these basic needs, but they are among the oldest in the country and may not suffice the needs of a growing population. Meanwhile, ambitious city-planning documents recognize opportunities for holistic planning focused on resource efficiency and long-term sustainability. This thesis aims to develop a foundation for quantitative modelling of how water and energy consumption may be affected by political decisions in New York City. The MARKAL (MARKet ALlocation) framework, commonly used to model long-term energy systems developments, is expanded to include the NYC’s water system. Relevant water system technologies are quantified with economic parameters, energy input and greenhouse gas emissions to give an as realistic as possible description of the entire water system. When combined with the existing MARKAL-model over NYC's energy system, the test runs of the model clearly shows impacts on energy consumption from water system regulations. These preliminary results are not applicable to support urban policy-making at this stage. However, with further development of the model as well as improvements in data quality it is perceived that this integrated water-energy model has the potential to become a powerful decision support tool for joint planning of water and energy systems developments in New York City. This Master thesis has been conducted in collaboration with the Energy Policy and Technology Analysis Group of the Sustainable Energy Technologies Department at Brookhaven National Laboratory, U.S.A.

Doutoramento em Ciências e Engenharia do Ambiente
As cidades, áreas que albergam cerca de 70% da população europeia, enfrentam hoje um conjunto de desafios associados a alterações do metabolismo urbano, que num contexto de alteração climática (AC), afectam o microclima urbano e a qualidade do ar (QA). Compreender a interação entre as AC, qualidade do ar e fluxos urbanos de calor (FUC) é um tópico de investigação emergente, reconhecido como área de interesse para a definição e implementação de políticas locais. O principal objetivo do presente trabalho é promover uma avaliação integrada das interações entre medidas de resiliência urbana e as AC, e respectiva influência no microclima urbano, QA e FUC, tendo como caso de estudo a cidade do Porto (Portugal). Pretende-se ainda impulsionar o desempenho dos modelos numéricos para que estes representem realisticamente os fenómenos físicos que ocorrem nas áreas urbanas. Para atingir este objetivo, o sistema de modelos WRF-SUEWS foi aplicado para a área de estudo para avaliar a influência de diferentes níveis de área urbanizada nas trocas de calor entre a superficie e a atmosfera. O modelo foi validado mediante a comparação dos seus resultados com dados medidos obtidos em campanhas de monitorização de fluxos. A influência das variáveis meteorológicas nos FUC, e a forma como estas, por sua vez, são influenciadas pela superfície urbana foi também avaliada. Para tal, o sistema WRF-SUEWS foi aplicado para 1-ano representativo de um período de clima presente (1986-2005) e de clima futuro de médio prazo (2046-2065). O cenário climático futuro foi projetado tendo por base o cenário RCP8.5. Esta análise permitiu quantificar e mapear os efeitos das AC nos FUC na cidade do Porto. Face à necessidade corrente de aumentar a resiliência urbana a futuros eventos meteorológicos extremos (e.g. ondas de calor), o sistema WRF-SUEWS foi ainda aplicado (com uma resolução espacial de 200 m) para avaliar a influência de medidas de resiliência nos FUC. Conhecendo a importância da morfologia urbana para as características do seu próprio clima, um conjunto de parameterizações urbanas (LSM, SUEWS e UCM) foram analisados para área de estudo, por forma a obter uma representação realista das características urbanas no modelo WRF e, consequentemente, obter um melhor desempenho na modelação da QA à escala local. Os resultados revelaram que o modelo UCM é a parameterização urbana que melhor representa os fluxos turbulentos de calor, a temperatura e velocidade do vento à superfície. Como resultado, o modelo CFD VADIS, inicializado pelo modelo WRF-UCM, foi aplicado com uma elevada resolução espacial (3 m) a um bairro típico da cidade do Porto. As simulações realizadas permitiram caracterizar o estado atual da QA na área de estudo, bem como avaliar a influência de diferentes medidas de resiliência nos padrões de velocidade do vento e na concentração de poluentes atmosféricos (PM10, NOX, CO e CO2). Este trabalho constitui uma ferramenta científica inovadora no que diz respeito ao conhecimento dos processos físicos que ocorrem à escala urbana, proporcionando uma visão integradora entre AC, QA e FUC. Estes resultados são relevantes para o apoio à decisão política do que respeita à implementação de estratégias que permitam aumentar a resiliência urbana, nas suas diversas vertentes, a um clima em mudança
Cities, home of about 70% of the European population, are facing important challenges related to changes in urban structure and its metabolism, and to pressures induced by climate change (CC) effects, which are affecting urban microclimate and air quality. The better understanding of the interactions between CC, air quality and urban surface energy balance (USEB) is an emerging priority for research and policy. The main objective of the current study is to provide an integrated assessment of the interaction between resilience measures and CC effects, and its influence on the urban microclimate and air quality as well as on the USEB, having as case study the city of Porto (Portugal). The ultimate goal is to improve the accuracy of numerical modelling to better represent the physical processes occurring in urban areas. For this purpose, the relevant parameters to both USEB and air quality were analysed. The WRF-SUEWS modelling setup was applied to the study area to assess the influence of different levels of urbanization on the surface-atmosphere exchanges. To validate the modelling setup, the results were compared with measurements carried out on field campaigns. The way of how the meteorological variables affect the USEB and how, in turn, these variables are themselves affected by urban surface was also assessed. The modelling setup was applied for 1-year period statistically representative of a present (1986-2005) and medium-term future (2046-2065) climate. The climate projection was produced under the RCP8.5 scenario. This analysis gives insights of how the urban-surface exchanges will be affected by CC, allowing the mapping of the FUC over the study area. As result of the need of increase cities resilience to future extreme weather events (e.g. heat waves), the WRF-SUEWS model (with a spatial resolution of 200 m), was applied to Porto city to evaluate the influence of a set of resilience measures on the USEB. Knowing the importance of urban surfaces to its own microclimate, a set of urban parameterization schemes (LSM, SUEWS and UCM) were analysed for the study area, to achieve a more accurate representation of urban features in the WRF model and, in consequence, to improve the capability of air quality modelling at urban/local scale. The results point out that the UCM is the urban parameterization that provides a more realistic representation of the turbulent energy fluxes and the near-surface air temperatures and wind speed. As result, a CFD modelling (VADIS), forced by WRF-UCM, was used to provide a set of numerical simulations with a high spatial resolution (3 m) over a typical neighbourhood in the Porto city. These simulations allow the characterization of the current air quality status over the study area, as well as the assessment of the influence of different resilience measures in the wind flow and air pollutants dispersion (PM10, NOX, CO and CO2). Overall, this research work is a step forward in understanding the physics of urban environments, providing also a linkage between CC, air quality and USEB. These findings are highly advantageous to support policy makers and stakeholders helping them to choose the best strategies to mitigate extreme weather events and air pollution episodes and so increase cities resilience to a future climate.

Complying with the Paris agreements requires substantial efforts in the building sector, and especially within the existing building stock which is responsible for a considerable amount of emissions and energy consumption. This master thesis focuses on the residential district of Minneberg, located in the west of Stockholm in Bromma. The urban building energy modelling (UBEM) approach is used to model the situation of the current district. This method uses real-life data provided by the district, as well as information found in energy performance certificates and in public databases. Based on that, a virtual archetype building representing the whole district is modelled and calibrated. Suitable energy-efficient solutions that can contribute to reducing the energy consumption are identified and applied in two different scenarios. The first scenario consists in retrofitting the current building stock, while the second represents the case where the building has to be designed from scratch today to comply with Boverket’s requirements on nearly zero-energy buildings ("New Minneberg" scenario). The aggregation of the results shows that the current district is already quite energy-efficient, with the installation of solar panels seeming to be the only economically viable retrofitting option. As for the "New Minneberg" scenario, it is possible to comply with the requirements and achieve a C-class building by reducing the primary energy consumption, but that comes at the expense of a higher actual energy consumption.
Att följa Parisavtalen kräver stora ansträngningar inom byggsektorn, och särskilt inom det befintliga byggnadsbeståndet som står för en betydande mängd växthusgasutsläpp och energianvändning. Examensarbetet fokuserar på det svenska bostadsområdet av Minneberg, som ligger i västra Stockholm i Bromma. UBEM-metoden (urban building energy modelling) används för att modellera situationen i det nuvarande distriktet. Metoden använder verkliga data från fastighetsområdet, liksom information som finns i energideklarationer och offentliga databaser. Därefter modelleras och kalibreras en virtuell arketypsbyggnad som representerar hela distriktet. Lämpliga energieffektiva lösningar som kan bidra till att minska energiförbrukningen identifieras och tillämpas i två olika scenarier. Det första scenariot består i renovering av det nuvarande byggnadsbeståndet, medan det andra representerar fallet om byggnaden hade designats från grunden idag, för att uppfylla Boverkets krav på nollenergihus ("New Minneberg" scenario). Resultaten visar att det nuvarande distriktet redan är ganska energieffektivt, där installation av solpaneler verkar vara den enda ekonomiskt lönsamma åtgärden. Gällande "New Minneberg" scenariot är det möjligt att uppfylla kraven och uppnå en C-klass byggnad genom att minska primärenergitalet, men det resulterar i en högre verklig energiförbrukning.

Les projections climatiques prévoient une amplification du réchauffement climatique, potentiellement exacerbée en milieu urbain du fait du phénomène d’îlot de chaleur urbain. La recrudescence d’évènements extrêmes comme les canicules peut avoir des conséquences écologiques, sanitaires, et économiques dramatiques à l’échelle des villes qui concentrent la population. Parmi les mesures d’adaptation visant à améliorer le confort climatique et la demande énergétique, la climatisation et le verdissement urbain constituent deux leviers d’action aux effets parfois antagonistes. Ce travail de thèse – mené dans le cadre des trois projets de recherche CLIM2, MUSCADE et VegDUD, propose d’évaluer ces effets par des simulations du climat urbain à l’échelle de l’agglomération parisienne. La modélisation repose en particulier sur le modèle de canopée urbaine TEB qui permet de simuler les échanges de chaleur, d’eau et de quantité de mouvement entre les surfaces urbaines et l’atmosphère, et depuis peu l’énergétique des bâtiments et des indices de confort thermique dans les bâtiments et dans les rues. Afin d’améliorer la prise en compte de la végétation urbaine dans TEB, un modèle de toitures végétalisées extensives a tout d’abord été développé et évalué. Différentes pratiques d’arrosage de la végétation urbaine au sol ou sur les toits ont également été paramétrées. Les scénarios d’adaptation de la ville de Paris par la climatisation, évalués dans le cadre de CLIM2 pour la canicule 2003 par des simulations couplées de TEB avec un modèle atmosphérique, ont mis en évidence que toutes les formes de climatisation qui rejettent de la chaleur dans l’atmosphère (sèche ou humide) génèrent une augmentation de la température des rues au niveau des piétons. Ce réchauffement, proportionnel à la puissance des rejets de chaleur sensible dans l’atmosphère, est en moyenne de 0.5 à 2°C, selon le niveau de déploiement de la climatisation. Différentes stratégies de verdissement ont ensuite été mises en œuvre et évaluées toujours sur Paris, en faisant varier soit la végétation au sol (plusieurs taux et types de végétation testés), soit celle en toiture (avec ou sans arrosage), soit les deux. Ces simulations, réalisées dans la configuration générale du projet MUSCADE, i.e. en mode forcé avec une version de TEB disposant d’un générateur dynamique d’îlot de chaleur urbain, ont montré que l’augmentation de la couverture végétale au sol a un pouvoir rafraîchissant plus efficace que les toitures végétalisées, et ce d’autant plus que le taux de verdissement et que la proportion d’arbres sont importants. Les toitures végétalisées quant à elles constituent le moyen le plus efficace de réduire la consommation d’énergie, non seulement estivale mais aussi à l’échelle annuelle, essentiellement grâce à leur pouvoir isolant
Climate projections predict an amplification of global warming, potentially exacerbated in urban areas by the urban heat island effect. More frequent extreme events such as heat waves may have severe public health, ecological, and economic consequences as cities concentrate population. Among the measures aiming at improving thermal comfort or energy demand, air conditioning and urban greening are measures that may have antagonistic effects. This PhD work is undertaken within the framework of three research projects, CLIM2, MUSCADE and VegDUD. Its objective is to evaluate the respective effects of air conditioning and urban greening based on urban climate simulations across the Paris area. The modelling relies on the Town Energy Balance (TEB) model, which simulates the exchange of heat, water and momentum between the urban surface and the atmosphere. It has been recently improved to simulate building energetics, as well as indoor and outdoor thermal comfort indices. To improve the description of urban vegetation within TEB, a green roof model has been developed and evaluated. In addition, watering practices have been implemented to model the watering of urban vegetation at ground or roof level. Within CLIM2, the air conditioning scenarios tested for adapting Paris city to the extreme temperatures of the 2003 heatwave have been evaluated based on simulations using TEB coupled with an atmospheric model. Results shows that all forms of conditioning that release waste heat (dry or wet) into the atmosphere generate a temperature increase in the streets. This warming is proportional to the power of the sensible heat releases in the atmosphere and is on average 0.5 to 2_C, depending on the level of deployment of the air conditioning. Then, the greening of Paris city has been evaluated based on simulations carried out with the general configuration of the MUSCADE project, i.e. with climate forcings and a dynamic urban heat island generator. The scenarios tested consisted in an increase in ground-base vegetation or an implementation of green roofs on compatible buildings, or the two combined, with the option of watering green roofs or not in summer. Results show that increasing the ground cover has a stronger cooling effect than implementing green roofs, and even more so when the greening rate and the proportion of trees are important. The green roofs are however the most effective way to reduce energy consumption, not only in summer but also on an annual basis, mainly due to their insulating properties

Le milieu urbain est à l'origine de processus radiatifs, thermiques, dynamiques et hydriques qui modifient le climat de la ville. La couche superficielle du sol, avec la présence plus ou moins importante de surfaces végétales ou d'eau, les activités humaines qui induisent des rejets de chaleur et de polluants, et la structure urbaine, avec des matériaux de construction et une certaine morphologie du cadre bâti, sont les principaux facteurs de cette modification. Le bilan d'énergie thermique permet d'appréhender la majorité des perturbations générées par la ville. A l'aide du schéma Town Energy Balance, développé par Météo-France pour paramétrer les échanges en énergie et en eau entre les surfaces bâties et l'atmosphère, nous avons effectué des tests de sensibilité du bilan d'énergie à différents facteurs. Ces facteurs appartiennent à cinq domaines d'actions : le bâtiment, l'espace public, l'organisation urbaine, les activités industrielles et les transports. Nos différentes simulations ont permis de confirmer le rôle prédominant des paramètres radiatifs dans le bilan d'énergie de la ville en été. Durant l'hiver, ce sont d'autres paramètres thermiques (isolation) qui ont la plus grande influence. Les collectivités territoriales françaises ont à leur disposition plusieurs outils et moyens pour agir en faveur de leur environnement climatique et intégrer des facteurs influant sur le climat urbain : leurs domaines de compétence directe (voirie, bâtiments communaux, espaces verts, etc.), les documents stratégiques d'orientation (SCOT et PLU), les procédures d'aménagement (ZAC et lotissement), l'incitation et l'information de leurs citoyens et de leurs services (Agenda 21 local, Plan Climat Territorial, Approche Environnementale de l'Urbanisme). Elles ne peuvent cependant pas agir avec une liberté suffisante, compte tenu des limites contraignantes entre droit de l'urbanisme et droit de la construction et de l'habitat

Les territoires ruraux disposent du principal gisement d’énergie renouvelable en France. Les réseaux énergétiques y sont moins denses que dans les zones urbaines et certains vecteurs, tels que le gaz, en sont souvent absents. Or, alors que les systèmes énergétiques urbains ont été abondamment étudiés, les spécificités de la demande énergétique rurale restent méconnues, notamment dans le secteur résidentiel. Des travaux récents mettent en avant les enjeux liés à la décentralisation du système énergétique français et le besoin d’une connaissance fine de l’offre et de la demande, tant sur le plan spatial que temporel. Ce travail de thèse poursuit deux objectifs. Tout d’abord il s’attache à identifier les spécificités de la consommation énergétique des logements ruraux par rapport aux logements urbains. Ensuite, il vise à analyser la réponse que peut apporter le gisement local d’énergie renouvelable à la demande résidentielle sur un territoire mixte urbain-rural, dans une optique de territoire à énergie positive – équilibre annuel entre l’offre et la demande énergétique du territoire
Rural areas have the main resources of renewable energy in France. Energy networks are less dense there than in urban areas and some energy vectors, like gas, are often missing. However, as urban energy systems have been widely studied, the specificities of rural energy demand remain little-known, especially for the residential sector. Recent works highlight new challenges related to decentralization of the French energy system and the need for fine knowledge of demand and supply, on both spatial and time scales. This research work pursues two objectives. First, it commits to identify the specificities of rural housing energy consumption. Then, it aims at analyzing the potential response of local renewable energy sources to the residential demand in a mixed urban-rural territory, in a 100 % RES process – equilibrium between annual energy demand and supply on the territory

L'adaptation des villes au changement climatique constitue un enjeu majeur des politiques d’aménagement. Promouvoir l'intégration des infrastructures vertes et bleues dans l'environnement urbain entant que stratégies d'adaptation implique ainsi de comprendre leurs impacts sur les bilans en eau et en énergie. Un modèle hydro microclimatique,TEB-Hydro, a préalablement été développé en tenant compte du couplage détaillé des deux bilans. Cependant, des études récentes ont mis en cause la représentation des processus hydrologiques en sous-sol urbain. Ainsi, ce travail de thèse consiste à améliorer la composante hydrologique du modèle (drainage de l’eau du sol par les réseaux, écoulements souterrains vertical et latéral). Après calage,une évaluation hydrologique est réalisée sur deux bassins versants urbains de Nantes. Dans les deux cas, le calage fait ressortir la même configuration de simulation, malgré des morphologies différentes, ce qui est encourageant pour des applications du modèle en projection climatique. L’évaluation hydrologique met en avant les paramètres clés du modèle et démontre une amélioration du processus de l’infiltration de l’eau du sol dans le réseau d’assainissement. L’évaluation hydro-énergétique du modèle démontre une représentation satisfaisante des flux de chaleur sensible et latente. Le fonctionnement du modèle vis-à-vis de l’évapotranspiration est discuté via le prisme de la végétation et de la morphologie urbaine. Une première application de TEB-Hydro en contexte de changement climatique permet d’évaluer une méthode statistique existante de désagrégation et soulève la problématique de la représentation de la dynamique pluviométrique dans ce contexte
Adapting growing cities to climate change is a major challenge in planning policy. Promoting the integration of green and blue infrastructures in the urban environment as adaptation strategies implies understanding their impacts on both the urban hydrological and energy balance. A hydro-microclimate model,TEB-Hydro, was developed previously, taking into account detailed coupling between the two balances. However, first model evaluation studies on different urban catchments have questioned the representation of the hydrological processes in the urban subsoil. This PhD work consists of performing new developments on the models hydrological component (soil-water drainage by sewer networks, vertical and lateral subsoil flows). After calibration a hydrological evaluation is performed on two urban catchments in Nantes. In both cases, the calibration brings out the same simulation configuration, despite different catchment related properties. This is encouraging for applying the model on climate projection. The hydrological evaluation highlights the model key parameters as well as shows improvements concerning sewer soilwater infiltration processes. In addition, a hydro-energetic evaluation shows a satisfactory representation of sensible and latent heat fluxes. The model operation vis-à vis evapotranspiration processes is discussed through vegetation and urban morphology. A first application of TEB-Hydro in climate change context enables evaluating an existing statistical disaggregation method as well as raises the problematic in representing rainfall dynamics for climate projection purposes

abstract: The combination of rapid urban growth and climate change places stringent constraints on multisector sustainability of cities. Green infrastructure provides a great potential for mitigating anthropogenic-induced urban environmental problems; nevertheless, studies at city and regional scales are inhibited by the deficiency in modelling the complex transport coupled water and energy inside urban canopies. This dissertation is devoted to incorporating hydrological processes and urban green infrastructure into an integrated atmosphere-urban modelling system, with the goal to improve the reliability and predictability of existing numerical tools. Based on the enhanced numerical tool, the effects of urban green infrastructure on environmental sustainability of cities are examined. Findings indicate that the deployment of green roofs will cool the urban environment in daytime and warm it at night, via evapotranspiration and soil insulation. At the annual scale, green roofs are effective in decreasing building energy demands for both summer cooling and winter heating. For cities in arid and semiarid environments, an optimal trade-off between water and energy resources can be achieved via innovative design of smart urban irrigation schemes, enabled by meticulous analysis of the water-energy nexus. Using water-saving plants alleviates water shortage induced by population growth, but comes at the price of an exacerbated urban thermal environment. Realizing the potential water buffering capacity of urban green infrastructure is crucial for the long-term water sustainability and subsequently multisector sustainability of cities. Environmental performance of urban green infrastructure is determined by land-atmosphere interactions, geographic and meteorological conditions, and hence it is recommended that analysis should be conducted on a city-by-city basis before actual implementation of green infrastructure.
Dissertation/Thesis
Doctoral Dissertation Civil and Environmental Engineering 2016

Modelling solar radiation data at a high spatiotemporal resolution for an urban environment can inform many different applications related to climate action, such as urban agriculture, forest, building, and renewable energy studies. However, the complexity of urban form, vastness of city-wide coverage, and general dearth of climatological information pose unique challenges doing so. To address some climate action goals related to reducing building emissions in the City of Victoria, British Columbia, Canada, applied geomatics and climatology were used to model solar radiation data suitable for informing renewable energy feasibility studies, including photovoltaic system sizing, costing, carbon offsets, and financial payback. The research presents a comprehensive review of solar radiation attenuates, as well as methods of accounting for them, specifically in urban environments. A novel methodology is derived from the review and integrates existing models, data, and tools – those typically available to a local government. Using Light Detection and Ranging (LiDAR), a solar climatology, Esri’s ArcGIS Solar Analyst tool, and Python scripting, daily insolation (kWh/m2) maps are produced for the city of Victoria. Particular attention is paid to the derivation of daily diffuse fraction from atmospheric clearness indices, as well as LiDAR classification and generation of a Digital Surface Model (DSM). Novel and significant improvements in computation time are realized through parallel processing. Model results exhibit strong correlation with empirical data and support the use of Solar Analyst for urban solar assessments when great care is taken to accurately and consistently represent model inputs and outputs integrated in a methodological approach.
Graduate

The urban landscape-heat-health relationship was explored using a model of human thermal comfort (as energy budget) modified to incorporate varying urban landscape. Census Tract-level energy budget was modelled in Toronto during four extreme heat events. Energy budgets (~+80 W m-2) and heat-related ambulance calls (~+10%) increased during heat events and were positively correlated, albeit with some event-to-event fluctuation in relationship strength. Heat-related calls were negatively correlated to canopy cover. “Cooling” design strategies applied to two high-energy budget Census Tracts nearly neutralized (~–25 W m-2) thermal comfort and increased canopy cover (500–600%), resulting in an estimated 40–50% reduction in heat-related ambulance calls. These findings advance current understanding of the urban landscape-heat-health relationship and suggest straightforward design strategies to positively influence urban heat-health. This new high-throughput, Census Tract-level thermal comfort modelling methodology incorporates the complexities of the urban landscape has relevance to landscape architecture, urban design, and public health.