abstract: The students of Arizona State University, under the mentorship of Dr George Karady, have been collaborating with Salt River Project (SRP), a major power utility in the state of Arizona, trying to study and optimize a battery-supported grid-tied rooftop Photovoltaic (PV) system, sold by a commercial vendor. SRP believes this system has the potential to satisfy the needs of its customers, who opt for utilizing solar power to partially satisfy their power needs. An important part of this elaborate project is the development of a new load forecasting algorithm and a better control strategy for the optimized utilization of the storage system. The built-in algorithm of this commercial unit uses simple forecasting and battery control strategies. With the recent improvement in Machine Learning (ML) techniques, development of a more sophisticated model of the problem in hand was possible. This research is aimed at achieving the goal by utilizing the appropriate ML techniques to better model the problem, which will essentially result in a better solution. In this research, a set of six unique features are used to model the load forecasting problem and different ML algorithms are simulated on the developed model. A similar approach is taken to solve the PV prediction problem. Finally, a very effective battery control strategy is built (utilizing the results of the load and PV forecasting), with the aim of ensuring a reduction in the amount of energy consumed from the grid during the “on-peak” hours. Apart from the reduction in the energy consumption, this battery control algorithm decelerates the “cycling aging” or the aging of the battery owing to the charge/dis-charges cycles endured by selectively charging/dis-charging the battery based on need. ii The results of this proposed strategy are verified using a hardware implementation (the PV system was coupled with a custom-built load bank and this setup was used to simulate a house). The results pertaining to the performances of the built-in algorithm and the ML algorithm are compared and the economic analysis is performed. The findings of this research have in the process of being published in a reputed journal. / Dissertation/Thesis / Masters Thesis Electrical Engineering 2018

A utilização de coberturas verdes nas edificações traz vantagens como a regulação das temperaturas no ambiente construído, a melhora na eficiência energética, a retenção das águas pluviais, a atenuação dos efeitos das ilhas de calor e o aumento da biodiversidade no ambiente urbano. O objetivo desta pesquisa é analisar experimentalmente o comportamento térmico de um sistema extensivo de cobertura verde em comparação com uma cobertura controle sem vegetação no período de transição entre as estações primavera-verão. O experimento foi composto por duas plataformas de teste construídas de forma a reproduzir um sistema de cobertura verde extensivo, sendo que uma plataforma recebeu o plantio de grama-amendoim e a outra foi mantida sem cobertura vegetal. Foram monitoradas as temperaturas dos níveis superior e inferior do substrato e também as temperaturas externas, abaixo da base das plataformas, por meio de termopares instalados em locais pré-determinados conectados a um sistema de aquisição de dados. Os dados de radiação solar global e das principais variáveis climáticas foram registrados pela estação meteorológica automática do Centro de Recursos Hídricos e Estudos Ambientais (CRHEA) da Universidade de São Paulo (USP) em Itirapina- SP, local onde foi conduzido o estudo. As análises do comportamento térmico foram realizadas a partir das abordagens espacial e temporal da Climatologia Dinâmica como forma de conhecer a influência das flutuações do tempo meteorológico possibilitando a identificação de episódios climáticos e suas repercussões sobre os valores das temperaturas obtidas das plataformas de teste através da elaboração e análise de gráficos, com o auxílio das cartas sinóticas e imagens de satélite, para identificação do episódio representativo e escolha dos dias típicos experimentais. Os resultados indicaram que a cobertura verde apresentou melhor desempenho térmico em relação à cobertura controle por ter apresentado maior atraso térmico entre as superfícies superior e inferior, menor amplitude térmica nas superfícies e temperaturas máximas menores do que a temperatura máxima do ar. Concluiu-se que, para um dia quente e seco, a cobertura do substrato com uma camada densa de vegetação influencia os processos de troca de calor no perfil do substrato pelo bloqueio de parte da radiação solar incidente, fator principal que determina esses processos, permitindo que a superfície superior não atinja temperaturas acima da temperatura máxima do ar diária e também que esta temperatura se manifeste com maior atraso na superfície inferior. / The use of green roofs in buildings brings advantages such as the regulation of temperatures in the built environment, the improvement in energy efficiency, storm water retention, mitigating the heat islands effect and increasing biodiversity in the urban environment. The aim of this study is to analyze experimentally the thermal behavior of an extensive green roof system compared to a control roof with just soil layer in spring-summer transition period. The experiment consisted of two test platforms built to reproduce an extensive green roof system, one of wich was planted with perennial peanut and the other one was kept without vegetation. The temperatures of the upper and lower levels of the substrate and also external temperatures below the base of the platforms were monitored by means of thermocouples installed in predetermined locations connected to a data acquisition system. Global solar radiation data and the main climatic variables were recorded by the automatic weather station at the Centre for Water Resources and Environmental Studies (CRHEA), University of São Paulo (USP) in Itirapina-SP, where the study was conducted. The analysis of the thermal behavior was based on the spatial and temporal approaches of dynamic climatology to know the influence of weather fluctuations enabling the identification of climatic episodes and their impact on the temperature values obtained from the test platforms by means of charts and verified by synoptic maps and satellite imagery for the identification of the representative episode and choice of the typical experimental days. The results indicated that green roof showed better thermal performance compared to control coverage by having larger thermal lag between the upper and lower surfaces, the lower temperature range on surfaces and lower maximum temperatures than the maximum air temperature. It was concluded that for a hot, dry day, a layer of a dense vegetation cover influences the heat exchange process in the substrate layer by blocking a part of the solar radiation, the main factor that determines these processes, allowing the upper surface does not reach temperatures above the maximum daily air temperature and also that this temperature be registred with higher delay at the bottom surface.

A utilização de coberturas verdes nas edificações traz vantagens como a regulação das temperaturas no ambiente construído, a melhora na eficiência energética, a retenção das águas pluviais, a atenuação dos efeitos das ilhas de calor e o aumento da biodiversidade no ambiente urbano. O objetivo desta pesquisa é analisar experimentalmente o comportamento térmico de um sistema extensivo de cobertura verde em comparação com uma cobertura controle sem vegetação no período de transição entre as estações primavera-verão. O experimento foi composto por duas plataformas de teste construídas de forma a reproduzir um sistema de cobertura verde extensivo, sendo que uma plataforma recebeu o plantio de grama-amendoim e a outra foi mantida sem cobertura vegetal. Foram monitoradas as temperaturas dos níveis superior e inferior do substrato e também as temperaturas externas, abaixo da base das plataformas, por meio de termopares instalados em locais pré-determinados conectados a um sistema de aquisição de dados. Os dados de radiação solar global e das principais variáveis climáticas foram registrados pela estação meteorológica automática do Centro de Recursos Hídricos e Estudos Ambientais (CRHEA) da Universidade de São Paulo (USP) em Itirapina- SP, local onde foi conduzido o estudo. As análises do comportamento térmico foram realizadas a partir das abordagens espacial e temporal da Climatologia Dinâmica como forma de conhecer a influência das flutuações do tempo meteorológico possibilitando a identificação de episódios climáticos e suas repercussões sobre os valores das temperaturas obtidas das plataformas de teste através da elaboração e análise de gráficos, com o auxílio das cartas sinóticas e imagens de satélite, para identificação do episódio representativo e escolha dos dias típicos experimentais. Os resultados indicaram que a cobertura verde apresentou melhor desempenho térmico em relação à cobertura controle por ter apresentado maior atraso térmico entre as superfícies superior e inferior, menor amplitude térmica nas superfícies e temperaturas máximas menores do que a temperatura máxima do ar. Concluiu-se que, para um dia quente e seco, a cobertura do substrato com uma camada densa de vegetação influencia os processos de troca de calor no perfil do substrato pelo bloqueio de parte da radiação solar incidente, fator principal que determina esses processos, permitindo que a superfície superior não atinja temperaturas acima da temperatura máxima do ar diária e também que esta temperatura se manifeste com maior atraso na superfície inferior. / The use of green roofs in buildings brings advantages such as the regulation of temperatures in the built environment, the improvement in energy efficiency, storm water retention, mitigating the heat islands effect and increasing biodiversity in the urban environment. The aim of this study is to analyze experimentally the thermal behavior of an extensive green roof system compared to a control roof with just soil layer in spring-summer transition period. The experiment consisted of two test platforms built to reproduce an extensive green roof system, one of wich was planted with perennial peanut and the other one was kept without vegetation. The temperatures of the upper and lower levels of the substrate and also external temperatures below the base of the platforms were monitored by means of thermocouples installed in predetermined locations connected to a data acquisition system. Global solar radiation data and the main climatic variables were recorded by the automatic weather station at the Centre for Water Resources and Environmental Studies (CRHEA), University of São Paulo (USP) in Itirapina-SP, where the study was conducted. The analysis of the thermal behavior was based on the spatial and temporal approaches of dynamic climatology to know the influence of weather fluctuations enabling the identification of climatic episodes and their impact on the temperature values obtained from the test platforms by means of charts and verified by synoptic maps and satellite imagery for the identification of the representative episode and choice of the typical experimental days. The results indicated that green roof showed better thermal performance compared to control coverage by having larger thermal lag between the upper and lower surfaces, the lower temperature range on surfaces and lower maximum temperatures than the maximum air temperature. It was concluded that for a hot, dry day, a layer of a dense vegetation cover influences the heat exchange process in the substrate layer by blocking a part of the solar radiation, the main factor that determines these processes, allowing the upper surface does not reach temperatures above the maximum daily air temperature and also that this temperature be registred with higher delay at the bottom surface.

A central challenge of the twenty-first century is to transition to a low-carbon energy system to reduce the risks of climate change. For Pima County, Arizona, where electricity accounts for the majority of greenhouse gas emissions, this requires rapid deployment of grid-tied renewable energy resources. In light of this challenge, photovoltaic solar has emerged as an important solution, providing the top source of new US electric generating capacity installed in 2016. However, there is still no consensus about the optimal scale for solar (centralized power plants, or small, decentralized systems) and the socio-economic implications for low income households. This thesis explores the implications of rooftop solar for energy justice through empirical research about a southern Arizona electric utility rate case. Utilities argue that existing rate structures shift costs from solar owners to lower-income ratepayers, while critics say the utility's proposed rate changes are unjust and that rooftop solar benefits all ratepayers. Drawing on my empirical data and an urban political ecology (UPE) approach, I analyze competing narratives that speak to three types of justice: distributive, procedural, and recognition. While dominant justice claims revolve around the distribution of costs through rates, competing narratives emphasize procedural and recognition (in)justice. Focusing on political economy, power relations, and the materiality of the grid, I reframe the utility’s cost shift argument as a strategic narrative and explain why this justice claim is ultimately validated. I propose that UPE can further an energy justice analysis by understanding procedural and recognition injustice as systemic products of rate of return regulation and the material configuration of the electric grid.

Reducing global energy consumption is a common challenge faced by the human race due to the energy shortage and growing energy demands. The building sector bears a large responsibility for the total energy consumption throughout the world. In particular, it was concluded that existing buildings, which are usually old and energy-inefficient, are the main reason for the high energy consumption of the building sector, in view of the low replacement rate (about 1%-3% per year) of existing buildings by new energy-efficient buildings. Therefore, improving the energy efficiency of existing buildings is a feasible and effective way to reduce energy consumption and mitigate the environmental impact of the building sector. The high energy intensity and requirements of a green building policy are the main motivation of this study, which focuses on finding cost-effective solutions to green building retrofit and maintenance planning to reduce energy consumption and ensure policy compliance. As about 50% of the total energy usage of a general building is caused by its envelope system, this study first proposes a multi-objective optimization approach for building envelope retrofit planning in Chapter 2. The purpose is to maximize the energy savings and economic benefits of an investment by improving the energy efficiency of existing buildings with the optimal retrofit plans obtained from the proposed approach. In the model formulation, important indicators for decision makers to evaluate an investment, including energy savings, net present value and the payback period, are taken into consideration. In addition, a photovoltaic (PV) power supply system is considered to reduce the energy demand of buildings because of the adequate solar resource in South Africa. The performance degradation of the PV system and corresponding maintenance cost are built into the optimization process for an accurate estimation of the energy savings and payback period of the investment so that decision makers are able to make informed decisions. The proposed model also gives decision makers a convenient way to interact with the optimization process to obtain a desired optimal retrofit plan according to their preferences over different objectives. In addition to the envelope system, the indoor systems of a general building also account for a large proportion of the total energy demand of a building. In the literature, research related to building retrofit planning methods aiming at saving energy examines either the indoor appliances or the envelope components. No study on systematic retrofit plan for the whole building, including both the envelope system and the indoor systems, has been reported so far. In addition, a systematic whole-building retrofit plan taking into account the green building policy, which in South Africa is the energy performance certificate (EPC) rating system, is urgently needed to help decision makers to ensure that the retrofit is financially beneficial and the resulting building complies with the green building policy requirements. This has not been investigated in the literature. Therefore, Chapter 4 of this thesis fills the above-mentioned gaps and presents a model that can determine an optimal retrofit plan for the whole building, considering both the envelope system and indoor systems, aiming at maximizing energy savings in the most cost-effective way and achieving a good rating from the EPC rating system to comply with the green building policy in South Africa. As reaching the best energy level from the EPC rating system for a building usually requires a high amount of investment, resulting in a long payback period, which is not attractive for decision makers in view of the vulnerable economic situation of South Africa, the proposed model treats the retrofit plan as a multi-year project, improving efficiency targets in consecutive years. That is to say, the model breaks down the once-off long-term project into smaller projects over multiple financial years with shorter payback periods. In that way, the financial concerns of the investors are alleviated. In addition, a tax incentive program to encourage energy saving investments in South Africa is considered in the optimization problem to explore the economic benefits of the retrofit projects fully. Considering both the envelope system and indoor systems, many systems and items that can be retrofitted and massive retrofit options available for them result in a large number of discrete decision variables for the optimization problem. The inherent non-linearity and multi-objective nature of the optimization problem and other factors such as the requirements of the EPC system make it difficult to solve the building retrofit problem. The complexity of the problem is further increased when the target buildings have many floors. In addition, there is a large number of parameters that need to be obtained in the building retrofit optimization problem. This requires a detailed energy audit of the buildings to be retrofitted, which is an expensive bottom-up modeling exercise. To address these challenges, two simplified methods to reduce the complexity of finding the optimal whole-building retrofit plans are proposed in Chapter 4. Lastly, an optimal maintenance planning strategy is presented in Chapter 5 to ensure the sustainability of the retrofit. It is natural that the performance of all the retrofitted items will degrade over time and consequently the energy savings achieved by the retrofit will diminish. The maintenance plan is therefore studied to restore the energy performance of the buildings after retrofit in a cost-effective way. Maintenance planning for the indoor systems is not considered in this study because it has been thoroughly investigated in the literature. In addition, a maintenance plan for the PV system involved in the retrofit of this study is investigated in Chapter 2. / Thesis (PhD)--University of Pretoria, 2017. / Electrical, Electronic and Computer Engineering / PhD / Unrestricted

京都大学 / 0048 / 新制・課程博士 / 博士(農学) / 甲第21155号 / 農博第2281号 / 新制||農||1059(附属図書館) / 学位論文||H30||N5129(農学部図書室) / 京都大学大学院農学研究科地域環境科学専攻 / (主査)教授 川島 茂人, 教授 星野 敏, 教授 藤原 正幸 / 学位規則第4条第1項該当 / Doctor of Agricultural Science / Kyoto University / DFAM

Due to the combined effect of intense rainfall events together with the expected impact of climate change, this will put pressure on the existing and future infrastructure for storm water management. One of the challenges related to this is the combined sewer system which is still operating in large areas of many cities worldwide. In Stockholm, combined sewer represents around 50% of the total sewer pipe length. In a Combined sewer system, once the conveyed discharge exceeds the system capacity, the system overflows, which can result in a diverse range of health and environmental problems. The cause of overflow has been strongly linked to runoff from intense rainfall events. Therefore, a key proposal to overcome this problem is to disconnect runoff from hard surfaces. This research aims to investigate the impact of applying a rainwater harvesting (RWH) and reuse system to collect runoff water from roof surfaces in areas with combined sewer system. A simulation water balance model for a rooftop RWH system was developed and two reuse purposes were considered, which entails toilet flushing and garden irrigation within the property. The study area consists of one building block within Kungsholmen area in Stockholm. The obtained results indicate that applying such systems can reduce runoff to the sewer system. Toilet flushing reuse shows a higher reduction impact on sewer flow than the use for irrigation. Toilet flushing reuse reduces annual runoff volumes to sewer in a range of 49.5% - 93.4% while irrigation provided reduction in a range of 11.6% - 26.3%. Regarding number of times that overflow from the combined sewer system occurs, toilet flushing reuse demonstrated reduction of 40% - 100% while 20% to 60% was reduced by irrigation reuse. For overflow volume, a reduction rate of 11% to 100% was reached through toilet flushing in contrast to 9% to 43% reduction from irrigation reuse. 19% to 37% of toilet flushing water demand was covered by the tank, while arange of 48% to 100% was covered for irrigation demand. All these parameters were found to be sensitive to change in tank size where increasing the size result in higher flow reduction rates. When considering implementing a reuse system, it is important to consider the applicability of RWH and reuse within the specific property. In areas that are under development, either of the two reuses can be considered depending on local conditions. However, in already built up area it is difficult to introduce a system that requires significant adjustment to existing pipe networks, such as reuse systems for toilet flushing. Systems for outdoor irrigation are possible to implement in most situations. When it comes to tank size, the optimal size will depend on the intended reuse, the catchment area and the objective of the system. For example, if the main objective is to reduce potable water consumption, a smaller tank can be used compared to where the main objective is to reduce sewer overflow. Hence, when considering implementing a rainwater reuse systems, each project will need to consider the local conditions as well as the individual objectives when determining the optimal reuse purpose and tank size. A cost-benefit analysis should also be considered when determining the optimal tank size for the intended use.

This thesis investigates the acceleration amplification experienced by solar towers mounted on the rooftops of low-rise industrial buildings during a seismic event. Specifically, this thesis looks to assess the validity of using amplification factors adopted by the ASCE 7-05Minimum Design Loads for Buildings and Other Structures to approximate seismic acceleration amplification for roof-mounted solar towers. To investigate the validity of the ASCE 7-05 amplification factors, this thesis conducts timehistory analyses of three theoretical solar towers mounted on the roof of a case study building. The time history analyses are conducted in the finite element computer modeling program SAP 2000 using 30 historical ground motion records of varying frequency content. Based on the results of the time history analyses, modifications to the ASCE 7-05 provision specific to roof-mounted solar towers are proposed.

Den befolkningstillväxt som sker idag skapar utmaningar för det befintliga bostadsbeståndet och vår bostadsförsörjning. För att klara tillväxten bygger vi våra städer tätare och högre vilket skapar både möjligheter och utmaningar. Ett sätt att effektivisera redan exploaterad mark kan vara att genom vertikal förtätning skapa fler bostäder på befintlig bebyggelse. Syftet med detta examensarbete är att belysa hur våningspåbyggnad i en urban miljö kan gestaltas och vilken påverkan den kan ha på mikroklimatet. För att undersöka huruvida det är lämpligt att förtäta ett utvalt objekt genomfördes en lämplighetsanalys baserat på ett tidigare examensarbete av Larsheim (2007), vilken behandlar inventering av fastighetsbestånd för vertikal förtätning. Denna metod har bearbetats i samråd med planarkitekt på Luleå kommun innan den tillämpades på det utvalda förtätningsobjektet vilket renderade i att byggnaden kunde anses lämplig att förtäta på. För att beskriva byggnaden och dess närområdes arkitektoniska karaktär utfördes en analys enligt Thiis-Evensen (1994) metod. Med hjälp av Pena och Parshalls (2001) metod ”Problem seeking” syntetiserades den arkitektoniska karaktärsanalysen tillsammans med förtätningsteori och teori om mikroklimat. Syntesen gav ett förslag till gestaltningsprogram för hur våningspåbyggnaden skulle kunna gestaltas. Examensarbetet resulterade i ett gestaltningsförslag se del 6. Gestaltningsförslaget. Påbyggnaden består av 45 lägenheter som är placerad ovanpå ett befintligt parkeringshus i Luleå, bostäderna är fördelade på tre plan vilka vilar på en förlängd pelarstomme. Påbyggnaden öppnar upp för nya möjligheter till ett attraktivt boende i innerstaden och har dessutom kvalitativa grönytor för lek och socialt umgänge samt odlingsbara ytor i ett växthus. I syfte att positivt kunna påverka de förändringar som kan ske då stadens tak bebyggs har mikroklimatsanalyser utförts utifrån faktorerna sol, vind, luftkvalitet, ljud, snö samt fenomenet ”Urban heat islands”. Analyserna som utförts har påverkat val av form och material för det i del 6. presenterade gestaltningsförslaget. Det presenterade gestaltningsförslaget bör i ytterligare steg undersökas av annan part då detta inte kunnat utföras under examensarbetets gång. Den lämplighetsanalys som testats i detta examensarbete bör valideras och utformas i närmre samarbete med intressenter och kommun för att säkerställa att rätt kriterier och tillvägagångssätt används då lämplighet för påbyggnad ska bestämmas. / The current ongoing population growth creates challenges for the existing housing stock and our housing supply. To handle this population growth, our cities are being constructed higher and more densely, which creates new opportunities and challenges. One way to make use of the already exploited land could be by using the principle of vertical densification to raise the existing building height and thereby being able to create new housing opportunities. The purpose of this master thesis is to illustrate how a rooftop extension could be configured into an urban environment and what impacts this configuration might have on the microclimate for the subjected area. To study the eligibility for a densification on the selected object, a method of eligibility analysis was carried out. The method used is based on a previous degree project by Larsheim (2007), which deals with stocktaking and assessing property stocks for vertical densification. The redesigned method was before being used on the selected object for densification drafted in consultation with planning architect at Luleå municipality. The final usage of the method resulted in the building being considered suitable for densification. A site analysis was conducted with regards to the existing building and its vicinity with a method written by Thiis-Evensen (1994). The method is focused on describing the architectural nature of the site. This analysis, together with the selected theory of densification and microclimate, was synthesized using Pena and Parshall's (2001) method "Problem seeking", which rendered a suggestion of a program for how the building could be configured. This master thesis resulted in a design proposal for a rooftop extension, see part 6. Gestaltningsförslaget. The extension is located on top of an existing multistory car park building in the centre of Luleå. The rooftop extension contains 45 apartments and consists of three elevated planes that resides on an extended pillar construction. A large green open area on the inner courtyard unlocks new opportunities for an attractive accommodation in the inner city. It also give the residents a room for social play and interaction as well as the opportunity to use cultivable surfaces in a new greenhouse. A microclimate analysis was carried out based on solar, wind, air quality, sound, snow, and the phenomenon of Urban heat islands in order to positively change the impact that might occur when the city’s rooftops are being extended. The analysis carried out influenced the selection of form and material in the design stage for the design proposal presented in part 6. The design proposal presented should be further investigated by another party. The eligibility analysis conducted in this master thesis should be validated and designed in close collaboration with stakeholders and municipalities to ensure that the correct criteria and approaches are being used when the eligibility of the rooftop extension is to be determined.

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