published_or_final_version / Environmental Management / Master / Master of Science in Environmental Management

This study seeks to expand the range of climates and conditions in which free cooling from an economizer can replace air conditioning power consumption in residential applications. To explore this issue, we first discretize a simple building model in space and in time. We then solve the associated energy and mass balances for the estimated hourly heating and cooling loads and humidity conditions with respect to an annual climate profile. We propose a forecast-based algorithm to control the rate of outdoor airflow brought in by an economizer, in response to the upcoming cooling load to be experienced by the interior airspace. The algorithm takes advantage of a range of acceptable temperatures for thermal comfort by precooling the envelope overnight to delay the onset of cooling demand during the day. In order to consider the highest potential benefit from such an algorithm, we bypass the considerable problem of forecast accuracy by basing the inputs on the upcoming cooling load according to an initial simulation of the full year. On the whole, even with the forecast-based control, the results of the study have much in common with previous findings in the literature. Precooling works better to reduce cooling load in cases of higher thermal and moisture mass, but a humid climate severely restricts when free cooling is beneficial. For the example house considered here with the Austin climate and other assumptions, the effect of the proposed forecast-based economizer control was to greatly reduce the indoor air cooling load while greatly increasing the number of annual hours of unacceptably high indoor humidity. When we adjusted the forecast-based algorithm to avoid the excess humidity, the remaining reduction in cooling load was not significant. To investigate further how a forecast-based economizer could reduce cooling load in humid climates, the prinicipal task should be to extend the control algorithm to forecast and manage upcoming indoor humidity levels in the same fashion as was done in this study for indoor air temperature. / text

In computer networks, congestion is a condition in which one or more egressinterfaces are offered more packets than are forwarded at any given instant [1]. In wireless sensor networks, congestion can cause a number of problems including packet loss, lower throughput and poor energy efficiency. These problems can potentially result in a reduced deployment lifetime and underperforming applications. Moreover, idle radio listening is a major source of energy consumption therefore low-power wireless devices must keep their radio transceivers off to maximise their battery lifetime. In order to minimise energy consumption and thus maximise the lifetime of wireless sensor networks, the research community has made significant efforts towards power saving medium access control protocols with Radio Duty Cycling. However, careful study of previous work reveals that radio duty cycle schemes are often neglected during the design and evaluation of congestion control algorithms. This thesis argues that the presence (or lack) of radio duty cycle can drastically influence the performance of congestion control mechanisms. To investigate if previous findings regarding congestion control are still applicable in IPv6 over low power wireless personal area and duty cycling networks; some of the most commonly used congestion detection algorithms are evaluated through simulations. The research aims to develop duty cycle aware congestion control schemes for IPv6 over low power wireless personal area networks. The proposed schemes must be able to maximise the networks goodput, while minimising packet loss, energy consumption and packet delay. Two congestion control schemes, namely DCCC6 (Duty Cycle-Aware Congestion Control for 6LoWPAN Networks) and CADC (Congestion Aware Duty Cycle MAC) are proposed to realise this claim. DCCC6 performs congestion detection based on a dynamic buffer. When congestion occurs, parent nodes will inform the nodes contributing to congestion and rates will be readjusted based on a new rate adaptation scheme aiming for local fairness. The child notification procedure is decided by DCCC6 and will be different when the network is duty cycling. When the network is duty cycling the child notification will be made through unicast frames. On the contrary broadcast frames will be used for congestion notification when the network is not duty cycling. Simulation and test-bed experiments have shown that DCCC6 achieved higher goodput and lower packet loss than previous works. Moreover, simulations show that DCCC6 maintained low energy consumption, with average delay times while it achieved a high degree of fairness. CADC, uses a new mechanism for duty cycle adaptation that reacts quickly to changing traffic loads and patterns. CADC is the first dynamic duty cycle pro- tocol implemented in Contiki Operating system (OS) as well as one of the first schemes designed based on the arbitrary traffic characteristics of IPv6 wireless sensor networks. Furthermore, CADC is designed as a stand alone medium access control scheme and thus it can easily be transfered to any wireless sensor network architecture. Additionally, CADC does not require any time synchronisation algorithms to operate at the nodes and does not use any additional packets for the exchange of information between the nodes (For example no overhead). In this research, 10000 simulation experiments and 700 test-bed experiments have been conducted for the evaluation of CADC. These experiments demonstrate that CADC can successfully adapt its cycle based on traffic patterns in every traffic scenario. Moreover, CADC consistently achieved the lowest energy consumption, very low packet delay times and packet loss, while its goodput performance was better than other dynamic duty cycle protocols and similar to the highest goodput observed among static duty cycle configurations.

Cette étude porte sur l‘identification de modèles dynamiques pour l‘évaluation des performances et le diagnostic énergétique de bâtiments existants. Le travail de thèse se place donc dans un contexte d‘économie d‘énergie et d‘efficacité énergétique accrue qui sont d‘intérêt primordial aujourd‘hui. Nous nous adressons à des bâtiments de bureaux occupés mais relativement bien instrumentés. Nous disposons des mesures horaires de température extérieure, de rayonnement solaire, de puissance de chauffage, de puissance électrique et de température de l‘air intérieur. L‘objectif étant de proposer une démarche méthodologique permettant de quantifier les performances énergétiques de l‘enveloppe du bâtiment à partir des données disponibles, d‘une part, et de préconiser des voies pour leur amélioration, d‘autre part. Les étapes majeurs de la démarche d‘évaluation/diagnostic proposée s‘ajuste pour l‘essentiel sur celles d‘une procédure classique d‘identification : a) analyse préliminaire des données disponible ; b) choix des structures mathématiques susceptibles de reproduire convenablement le comportement dynamique du bâtiment ; c) estimation du modèle et validation ; et exploitation du modèle pour des fins d‘évaluation et de diagnostic. Grâce aux résultats obtenus par une première approche « boîte noire » nous effectuons une tentative de diagnostic énergétique approfondi en s‘appuyant sur une modélisation physique du bâtiment (« boîte blanche »). / This study concerns the identification of dynamic models for performance evaluation and energy diagnosis of existing buildings. The work of this PhD takes place in a context of energy conservation and energy efficiency which are of essential interest today. We are dealing with occupied office buildings but relatively well instrumented. We have hourly measurements of outdoor temperature, solar radiation, heating power, electrical power and indoor air temperature. The aim is to propose a methodological approach to quantify the energy performance of building envelope from the available data, on the one hand, and to recommend ways to improve them, on the other. Major steps of the process evaluation / diagnosis given for the most fits with those of a standard procedure of identification: a) preliminary analysis of available data, b) choice of mathematical structures for well describing the building behavior c) model estimation and validation, and operation of the model for evaluation and diagnosis. With the results obtained by a first approach "black box" we make a tentative of detailed diagnosis based on physical building model ("white box").

Master of Science / Department of Architecture / Michael D. Gibson / The use of Natural Ventilation (NV) to cool buildings in mixed climates can conserve significant cooling energy. In mixed climates it is particularly important during the fall and the spring, where appropriately designed buildings should use very little energy for heating or cooling. Natural ventilation is also important in residential buildings, where internal heat gain can be managed, making cooling by natural ventilation easier. Earlier investigations have clearly shown the economic, social, and health benefits of the use of NV in built environment. Studies have shown that increased airflow or air-speed during ventilation can bring a significant rise in comfort range which further reduces the cooling energy required to maintain comfort. The climatic data of the central United States (U.S.) shows that the availability of frequent high speed wind and favorable seasonal humidity conditions make natural ventilation feasible in late spring and early fall, where NV can offset most of the cooling demand for a home or multifamily residential unit, though it is not possible to maintain thermal comfort during the entire summer with NV alone. In mixed climates, NV for multifamily residential units has not been investigated thoroughly. According to 2009 International Residential Code, multifamily residential buildings are typically designed to use a code minimum amount of operable or ventilating windows, 4% of the floor area being ventilated, while also using lightweight construction methods (such as wood framing) that is prone to fast thermal response during the overheated periods of the year. While climate may favor the use of NV in these building types, the sizing of windows and the building construction type limit the potential to save energy with NV. This study hypothesized that the maximum benefits from NV in the climate of the central U.S. requires further optimization of window openings beyond the energy code minimum, and a construction system incorporating mass that can slow thermal response during overheated periods. During the study, the climatic data of the central US was scrutinized to understand the most suitable time frames where NV could be applied in order to maintain indoor thermal comfort in various construction systems in residential buildings: mainly lightweight using wood framing, and heavier construction using concrete and masonry. The location of the housing unit, first level or second level, was also examined to account for the differences in thermal gains and losses as a result of ground coupling and additional heat gain from the roof. Further, computational fluid dynamics evaluated the comfort achieved with different ventilation areas. Change in comfort hours by using NV tested the practicability of the use of NV to maintain indoor thermal comfort for different scenarios. The study concluded with design recommendations for building orientation, operable window size, and construction type as these factors relate to thermal comfort and the optimization of multifamily residential buildings to utilize NV for energy savings in the U.S.

Syftet med denna studie är att undersöka elevernas uppfattningar om materians uppbyggnad och om materians och energins bevarande. Den föreliggande studien baseras på en kvantitativ analys i form av en elektronisk enkät, som föregicks av en kvalitativ analys i form av, strukturerade intervjuer och demonstrationer. Eleverna har kunskap om vardagsnära exempel, som till exempel vad en stekpanna är uppbyggd av. De ansåg att dessa är exempel på materia men när det gäller mer abstrakta begrepp som ljus, magnetfält, skugga, vakuum, värme och ljud uppvisar eleverna mer osäkerhet och brist på kunskaper. Hälften av eleverna svarade att luft är materia, vilket tyder på ”gasblindhet” hos de övriga. Mellan 20 och 45 % av eleverna har inte kunskap om atomens uppbyggnad. Det framgick av studien att eleverna har svårt för materia- och energiomvandlingar i mer komplexa system såsom kolets kretslopp, vattnets kretslopp samt fotosyntesen. Gällande gasbildning och gaskännedom så framkom det att mer än hälften av eleverna hade kunskap om det. / The purpose of this study is to investigate students' perceptions of matter and conservation of matter and energy. This study is based on a quantitative analysis in the form of an electronic questionnaire, which was preceded by a qualitative analysis in the form of structured interviews and demonstrations. It is fairly easy for students to understand matter in questions about objects in everyday life, but more difficult in abstract concepts such as light, magnetic fields, shade, vacuum, heat and sound. Half of the students answered that air is matter, which indicates "gas blindness" of the other. Between 20 and 45 % of the students have poor knowledge of the structure of the atom. It appeared that students have problems with matter and energy transformations in more complex systems such as the carbon cycle, the water cycle and photosynthesis. Concerning gas formation and gas knowledge it appeared that half of the students had knowledge about the phenomena.

A dissertation submitted to the Faculty of Science, University of the Witwatersrand, in fulfilment of the requirements for the degree of Master of Science. Johannesburg, 2015. / Over 60% of the Swazi population resides in rural areas and rely on woodfuel for their daily cooking needs. Cooking with woodfuel on open fires is inefficient and unhealthy, leading to millions of deaths of women and children each year while also contributing to environmental degradation. This has necessitated the implementation of Government’s clean cookstoves programme in Swaziland. This study focused on household stove users in six chiefdoms in the Lower Usuthu Sustainable Land Management (LUSLM) Project area in Siphofaneni Swaziland. A survey conducted through the dissemination of a questionnaire was used to investigate how rural perceptions impact on the adoption of clean cookstove technologies as an alternative household energy technology contributing towards sustainable development in rural Swaziland. Results from this study indicate that although cooking on an open fire was the least desired cooking technology, only 2% of households in the project area own clean cookstoves and less than half of the households had knowledge of cookstoves. The study further revealed that over 80% of the households in the survey area would prefer using a clean cookstoves to reduce the labour intensive task of collecting firewood as well as reducing exposure to smoke. The households found to have some knowledge of the benefits of clean cookstoves indicated the willingness to pay for a clean cookstove; however, a third of the respondents indicated a preference of obtaining a free clean cookstove. The price and availability of the clean cookstove in rural areas were two main barriers to increased uptake of the stoves, coupled with the need to purchase new pots. Despite the general lack of awareness of these technologies, challenges such as danger of the stoves to children and stove durability were also cited. The results indicate the need for the ongoing clean cookstove programme being implemented by the Government of Swaziland to improve on its strategy, to focus on incorporation of perceptions of rural stove users in development of appropriate cookstove designs, distribution models, and the design and implementation of a cookstove quality control programme.

Esta pesquisa resultou na proposição de um conjunto de diretrizes que viabilizem a implementação e a redação de um projeto de regulamentação energética para edifícios de escritórios, no que se refere à luz natural. Para tanto, foi efetuado um levantamento das leis, normas e certificações em vigência nos países: Brasil, Estados Unidos, Canadá, Portugal, Reino Unido, França e Alemanha, que se referem à iluminação natural e sua interface com a iluminação artificial, em edifícios de escritórios. Foram incluídos neste conjunto de regulamentos, normas da ISO e CIE, por se tratarem de referências internacionais. A partir deste levantamento foram destacados e agrupados por assunto, os itens que continham indicadores para a avaliação da admissão de luz natural em prédios de escritórios. No Capítulo 5, Estudos de Caso, foram analisados cinco projetos de escritórios, de prédios construídos na cidade de São Paulo, quanto aos aspectos da insolação e admissão da luz natural. Os projetos foram simulados em computador e, pelos resultados obtidos com a aplicação do software Radiance, verificou-se a conformidade destes projetos com os indicadores coletados. Estas avaliações permitiram conclusões sobre os projetos e, também, sobre os indicadores utilizados. A partir destas conclusões foram apresentadas diretrizes para o caso brasileiro, apontando itens para regulamentos que quando aplicados otimizem o uso da luz natural nos ambientes de escritórios. / This research has resulted in the proposition of a group of directives which may enable the implementation and outlining of an energetic regulation project for office buildings as related to daylighting. To that end, current codes, norms and certification systems, in use in Brazil, United States, Canada, Portugal, United Kingdom, France, and Germany, all regarding daylighting and its interaction with artificial lighting in office buildings, were raised. We have added to this group of regulations the ISO and CIE norms, due to their being international references. Starting out from these regulations, the items that contain indicators for the evaluation of daylight admission in office buildings have been grouped and outlined by category. In chapter 5, Case Studies, five office buildings in Sao Paulo city have been analyzed regarding their insolation and daylight performance. The projects were computer-simulated and, through the results obtained by applying the Radiance software, the conformity of these projects with the collected indicators were verified. These evaluations led to conclusions about the projects, as well as about the used indicators. From these conclusions, directives have been presented for use in the Brazilian case, identifying items for regulations that, when applied, will optimize the use of daylight in offices.

Esta dissertação propõe um modelo de caracterização de recursos energéticos do lado da demanda que pretende abranger todos os tipos de ações e medidas referentes ao gerenciamento da demanda e à conservação energética, avaliando-as de forma holística, dentro de quatro dimensões: técnico-econômica, ambiental, social e política. Os recursos considerados na composição do modelo são submetidos às fases de Inventário de Recursos Energéticos do Lado da Demanda, Caracterização das Dimensões e Atributos de Avaliação de Recursos, Formulação dos Potenciais Energéticos e Aplicação do Modelo em Caso Piloto. O Inventário de Recursos Energéticos do Lado da Demanda pretende levantar, descrever e segmentar todas as alternativas energéticas de GLD e setores de consumo energético. A Caracterização da Avaliação de Recursos delimita as esferas de análise de recursos e a caracterização de seus atributos quanto a custos e benefícios provenientes de seu emprego. A Formulação dos Potenciais Energéticos define seu cálculo a partir de sua amplitude e restrições gerais de aplicação. O modelo é aplicado em um estudo piloto, na Região Administrativa de Araçatuba, por meio de um exercício de formulação do PIR, considerando a utilização de ferramentas de Avaliação dos Custos Completos, Cálculo de Potenciais Energéticos e Elaboração de Cenários de Projeção do Consumo Energético para um horizonte de tempo determinado. / This work presents a model for the characterization and assessment of demand side energy resources, which intends to comprehend every kind of action or measure related to demand side management and energy conservation, evaluated thouroughly into four dimensions: technical-economical, environmental, social and political. The resources included in the composition of the model are subjected to the stages of Inventary of Demand Side Resources, Characterization of Dimensions and Attributes of the Resources Assessment, Formulation of Energy Potentials and Model Application on a Real Case Study. The Inventary of Demand Side Resources intends to enlist, describe and segment all demand side management energy alternatives and their application in different economy sectors. The Characterization of the Resources Assessment defines the spheres of the assessment of resources and the characterization of its attributes as for costs and benefits resulting from their utilization. The Formulation of Energy Potentials defines their accounting based on their range and general application restrictions. The Model is applied in a case study, in the Administrative Region of Araçatuba, through an exercise of IRP formulation, regarding the utilization of Full Cost Accounting, Energy Potentials Accounting and Scenarios of Energy Consumption for a determined horizon.

Esse trabalho busca trazer uma contribuição efetiva e prática ao pensamento sustentável: \"Pense globalmente, aja localmente\", através da proposição de uma metodologia de avaliação assentada em uma visão integrada dos recursos naturais. Neste sentido, a necessidade de considerar a preservação dos recursos naturais, a redução da emissão de gases de efeito estufa, a conservação e a eficiência energética, se impõe como tema que deve ser abordado nos mais variados setores da economia, envolvendo desde uma visão global da matriz de consumo dos bens do planeta até uma abordagem microlocal, como, por exemplo, em empreendimentos relacionados aos setores residencial (residências, condomínios, prédios, áreas urbanas, etc.) e comercial (hotéis, shoppings, hospitais, restaurantes, etc.). A metodologia apresentada permite a análise da utilização dos recursos de forma racional, privilegiando, além da conservação e do uso eficiente, as sinergias nas suas utilizações. Assim, depois de levantadas as necessidades a serem atendidas em um empreendimento residencial ou comercial, bem como os recursos naturais disponíveis, será possível estabelecer, dentro das possibilidades factíveis, a combinação de recursos que represente o melhor aproveitamento na sua utilização como um todo, privilegiando de forma integrada a sustentabilidade. Para exemplificá-la e, simultaneamente, validá-la, a metodologia foi aplicada em um estudo de caso prático de uma residência. Assim, seguindo os passos metodológicos, inicialmente analisou-se a residência através de um balanço do fluxo de energia e matéria a partir das entradas de recursos naturais (energia, água, e outros recursos) e saídas (lixo, materiais e água com resíduos) que ocorrem nos processos e serviços da residência responsáveis pelo atendimento das necessidades humanas e do conforto, tais como: alimentação, higiene, iluminação, transporte, conforto térmico, lavagem de roupa, lazer e cultura, entre outros. Esta análise auxilia na identificação de perdas, desperdícios e possibilidades de transformações, permitindo, através da inclusão de tecnologias mais adequadas ambientalmente e do uso racional dos recursos, maior eficiência e conservação ao empreendimento. / This study aims to contribute effectively and practically to sustainable thinking: \"Think globally, act locally\", through the proposal of a methodology of evaluation established on an integrated vision of natural resources. Thus, the need to consider the preservation of natural resources, the reduction of gas emission which contributes to greenhouse effect, energy conservation and efficiency, stands as a subject that must be discussed in all economic sectors, involving a global view of the planet\'s natural resources to the microlocal approach, such as in residential sector entrepreneurship (houses, condominiums, buildings, urban areas, etc.) and commercial sectors (hotels, malls, hospitals, restaurants, etc.). The presented methodology allows the analysis of a rational way of utilization of resources, which enables conservation and efficient use, and the synergies of their utilizations. Thus, after identifying the needs to be met in a residential or commercial entrepreneurship, as well as the available natural resources, it will be possible to establish, within the feasibilities, a combination of resources which represents the best utilization as a whole, favoring sustainability in an integrated way. As an example, and also to validate it, the methodology was applied in a practical case study of a house. Thus, following the methodological steps, at first a house was analyzed through a balance of energy and materials based on natural resources inflow (energy, water, and others) and outflow (garbage and residual water or materials) which occurs in the household processes and services that attend to the human needs and comfort, such as: food, hygiene, lighting, laundry, cleaning, transportation, temperature control, leisure and culture, among others. This analysis helps to identify natural resources wastage and possibilities of changes, which warrant to the entrepreneurship a better efficiency and conservation, through the inclusion of technologies which are more suitable to the environment, and through a rational utilization of natural resources.