Wireless sensor networks (WSNs) are becoming increasingly pervasive in a number of applications. Due to the nature of WSNs, one of their biggest constraints is limited node energy. As WSNs grow in popularity, the prevalent issue remains to keep wireless sensor nodes alive for as long as possible, or risk disrupting the network. This dissertation develops a model based on the principles of game theory to improve the energy efficiency of wireless sensor nodes and increase the network lifetime by influencing the way routing takes place. The benefit of this model is a routing algorithm that is easily implementable and increases network lifetime by improving energy efficiency in the network. / MIng (Computer and Electronic Engineering), North-West University, Potchefstroom Campus, 2015

Published Article / The paper presents a critique of passive and active thermal comfort strategies. Extensive review of literature on passive thermal comfort energy efficiency interventions and their benefits was under taken. The paper explains the correlation between climatic comfort and energy efficiency. The applicability of the energy management process in ensuring energy efficiency is presented. Passive thermal comfort energy efficiency interventions have been seen to provide thermal comfort as well as energy efficiency. Their major shortcoming is their disability to work in all kinds of weather, heating in the winter and cooling in the summer. There is need to optimize passive thermal comfort energy efficiency interventions so that they provide heating in the winter and cooling in the summer.

This project consists on the Energy audit carried out on a residential building in Skutskär, property of the company Älvkarlebyhus, which is placed in the Älvkarleby municipality, belonging to Uppsala County in Sweden. The aim of the Energy audit is to obtain how much Energy is used, when is it used and how is it used. As well as the costs of the Energy use. The aim of the Energy audit also consists in reduces the Energy use applying efficiency measures. The audit carried out consist on identifying the heat losses and heat gains of the building, thus establishing an Energy balance that will reflect the Energy state of the building and finally propose some efficiency measures that could be applied. With this purpose, a strong method was developed in order to obtain as accurate results as possible. This method studies separately each component of the balance in order to get a better approach. The idea when working and present the results is to manage all the information in an easy way and present it in an easily understandable way for everyone, thus was used a spreadsheet. The expected results have been achieved; the difference between the heat losses and gains is of 0 MWh, which represents the balance 0 and all the values obtained are according to the experience values, which achieve the expected results. The total heat gain of the balance accounts for 1575,23 MWh. It is compounded by the District heating consumption which accounts 742,22 MWh that represents the 47 % of the heat gain and by the free heating which accounts for 832,79 MWh that represents the 53 %. The free heating is compounded by solar radiation which accounts for 643,36 MWh representing 41 % and for Internal heating which accounts for 189,43 MWh that represents 12 %. The total heat loss of the balance accounts for 1575,23 MWh. It is compounded by transmission losses which accounts for 875,46 MWh that represents 56 %, mechanical ventilation which accounts for 369,89 MWh that represents the 23 %, natural ventilation which account for 182,88 MWh that represents 12 % and hot tap water which account for 147 and represents 9 %. The efficiency measures will improve the Energy use in the buildings; especially in the cases were the Energy usage is too high, as in the case of transmission losses. Thus, the efficiency measures will be proposed mainly to alleviate the high values but also to improve other inefficient uses of the Energy. There are some efficiency measures proposed for every component of the balance and there is also some recommendation for the company in order to implement the most attractive ones, taking into account its profitability. These measures are only proposed and not studied deeply because of the main limitation of this thesis. Therefore, it is recommended to continue the study in order to examine and analyse deeply each measure, according to the energetic survey already done.

The building sector represents the largest energy consumer among the United States' end use sectors. As a result, the public and private sector will continue to place great emphasis on designing energy efficient buildings that minimize operating costs while maintaining a healthy environment for its occupants. Creating design-phase building energy models can facilitate the process of selecting life-cycle appropriate design strategies aimed at maximizing building energy efficiency. The primary objective of this research study is to gain greater insight into likely causes of variation between energy predictions derived from building energy models and building energy performance during post-occupancy. Identifying sources of error can be used to improve future modeling efforts that can potentially lead to greater accuracy and better decisions made during the building's design phase. My research approach is to develop a method for conducting retrospective analysis of building energy models in the areas that affect the building's predicted and actual energy consumption. This entails collecting pre-construction and post-occupancy related data from various entities that exhibit influence on the building's energy performance. The method is then applied to recently-constructed military dormitory buildings that utilized building energy modeling and now have actual, metered building energy consumption data. The study also examines how building occupancy impacts energy performance. The value of this work will provide additional insight to future building energy modeling efforts. / text

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Distributed imaging using sensor arrays is gaining popularity among various research and development communities. A common bottleneck within such an imaging sensor network is the large resulting data load. In applications for which transmission power and/or bandwidth are constrained, this can drastically decrease the network lifetime. In this dissertation, we consider a network of imaging sensors. We address the problem of energy-efficient communication of the resulting measurements. First, we develop a heuristic-based method that exploits the redundancy in the measurements of imaging sensors. The algorithm attempts to maximize the lifetime of the network without utilizing inter-sensor communication. Gains in network lifetime up to 114% are obtained when using the suggested algorithm with lossless compression. Our results also demonstrate that when lossy compression is employed, much larger gains are achieved. For example, when a normalized Root-Mean-Squared- Error of 0.78% can be tolerated in the received measurements, the network lifetime increases by a factor of 2.8, as compared to the lossless case. Second, we develop a novel theory for maximizing the lifetime of unicast multihop wireless sensor networks. An optimal centralized solution is presented in the form of an iterative algorithm. The algorithm attempts to find a Pareto Optimal solution. In the first iteration, the minimum lifetime of the network is maximized. If the solution is not Pareto Optimal a second iteration is performed which maximizes the second minimum lifetime subject to the minimum lifetime being maximum. At the nth iteration, the algorithm maximizes the nth minimum lifetime subject to the (n−1)th minimum lifetime being maximum, subject to the (n−2)th minimum lifetime being maximum, etc. The algorithm can be stopped at any iteration n. Third, we present a novel algorithm for the purpose of exploiting the inherent inter- and intra-sensor correlation in a network of imaging sensors while utilizing inter-sensor communication. This algorithm combines a collaborative compression method in conjunction with our cooperative multi-hop routing strategy in order to maximize the lifetime of the network. This CMT algorithm is demonstrated to achieve average gain in lifetime as high as 3.2 over previous methods. Finally, we discuss practical implementation considerations of our CMT algorithm. We first present some experimental results that illustrate the practicality of our method. Next, we develop a realistic optical model that permits us to consider a more heterogeneous network of cameras by allowing for varying resolution, intrinsic and extrinsic parameters, point-spread function and detector size. We show that our previous CMT algorithm can be extended to successfully operate in such a diverse imaging model. We propose new object-domain quality metrics and show that our proposed method is able to balance lifetime and fidelity according to expectations.

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Os sistemas de controle solar auxiliam no controle da radiação solar incidente no envoltório, e, de acordo com a NBR 15220-3, é recomendável seu uso para a zona bioclimática 3, na cidade de Porto Alegre. Assim, com a ação de retrofitting, é possível utilizar os sistemas de controle solar como modo de adaptar o envoltório das edificações ao clima local e aos padrões de consumo atuais. Dessa forma, o retrofitting do envoltório pode contribuir com a redução do consumo energético e a dependência de sistemas de refrigeração e aquecimento mecânico. Logo, o objetivo da dissertação é qualificar e quantificar energeticamente os sistemas de controle solar com vistas à redução do consumo energético nos ambientes construídos. Um estudo de caso foi realizado na cidade de Porto Alegre, onde um edifício foi selecionado perante um conjunto de edificações existentes. Com o auxílio de um método expedito de cálculo energético, foi realizada a avaliação energética do envoltório da edificação atual e do seu retrofitting proposto. A edificação passou de nível energético E para nível A, comprovando o êxito do estudo de retrofitting aplicado. A pesquisa concluiu que, alinhado com o encontrado na revisão da literatura, as edificações com grandes aberturas orientadas para oeste são um equívoco de projeto no clima de Porto Alegre e que as ações de retrofitting são uma alternativa de adaptação ao clima local, tornando os edifícios eficientes energeticamente. / Shading systems help to control the incident solar radiation on the envelope, and, according to NBR 15220-3, its use is recommended for the bioclimatic zone 3, in the city of Porto Alegre. Hence, with retrofitting, it is possible to use shading systems as a way of adapting the building envelope to the local climate and current consumption patterns. Thus, the retrofitting of the envelope can contribute to the reduction of the energy consumption and of the dependence on systems of refrigeration and mechanical heating. Therefore, the objective of this dissertation is to qualify and quantify the energy of shading systems in order to reduce energy consumption in built environments. Thus, a case study was conducted in the city of Porto Alegre, where a building was selected from a set of existing buildings. We performed an energetic evaluation of current envelope of buildings and its proposed retrofitting by using a facilitated method for energy calculation. The buildings moved from energy level E to level A, proving the success of the study on the applied retrofitting. We conclude that, as also shown in literature review; buildings with large openings oriented to the west in Porto Alegre are a design misconception due to the city’s climate. Thus, retrofitting actions are alternative ways to adapt to the local climate so that buildings are energy efficient.

Overreliance on energy from fossil fuels is unsustainable because of their regional depletion and associated environmental impacts. The British industrial sector accounts for around one fifth of final energy demand and one third of carbon emissions nationally. This thesis attempts to quantify the potential for industrial energy efficiency from the current baseline, by adopting thermodynamic and economic perspectives. The methodology involves a top-down analysis of energy trends within the manufacturing sector to determine the baseline against which changes are measured, leading to bottom-up case studies which explicitly consider the detailed mechanisms affecting energy demand. Top-down analysis highlights the diversity between industrial sectors, for which a sectoral classification based on process homogeneity is proposed. It also enables the long term, systemic potential for efficiency improvements to be estimated and identifies the barriers to uptake. Bottom-up case studies are better suited to identifying the sectoral potential in the short to medium term. Firstly, the technical potential for heat recovery from industrial sectors is quantified by recourse to thermodynamic quality and spatial considerations. Secondly, an energy and exergy analysis of a glass furnace enables a distinction between avoidable and unavoidable losses, leading to the identification of economic savings. Thirdly, a process integration study at a pulp and paper mill based on a pinch analysis and optimisation of a heat exchanger network highlights economic efficiency improvements. This thesis demonstrates that realising the full industrial energy efficiency potential requires improvements to public policy intended to overcome market-related barriers, especially the EU Emissions Trading Scheme and the Carbon Trust, with additional scope for a mandatory efficiency standard relating to motors. Energy efficiency has to part of a company’s overall strategy to be effective. Future work should focus on heterogeneous sectors and the broader effects on industrial energy efficiency of globalisation and the shift towards services.