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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
431

The New Pricing Model for District Heating : How it will affect Uppsalahem’s residential area August Södermans road

Kylberg, Isac, Hasselberg, Mollie, Gidlöf, Frida January 2015 (has links)
In January 2016 a new pricing model for district heating will be introduced by Vattenfall in Uppsala. The public housing corporation Uppsalahem is one of Vattenfall’s biggest customers and by using one of their residential areas, August Södermans road, a case study was made in order to examine how the new pricing model might affect Uppsalahem. According to Vattenfall one reason for the switch is to give incentive for their customers to use more energy efficient solutions. This was studied by modelling two energy efficient solutions for the houses at August Södermans road. By changing the ventilation systems to FTX and invest in improved windows, Uppsalahem would have been able to save 940 MWh for the year 2013 at August Södermans road. A comparison between the current and the new pricing model showed that Uppsalahem would save 9 000 SEK with the new pricing model applied on August Södermans road at its current condition. If the two energy efficient solutions were taken into consideration the new pricing model would result in a decrease with 21 000 SEK for the year 2013.
432

Building Sustainability : Studies on incentives in construction and management of real estate

Högberg, Lovisa January 2014 (has links)
This thesis summarizes the results from several studies with connection to sustainability in construction and management of real estate. Here, the concept sustainability includes environmental, social and economic dimensions and focus is on the actors with the best possibilities to impact real estate, namely the real estate owners and the developers. The thesis consists of six papers. Real estate owners’ perception of and incentives and strategies for sustainability was studied in four ways: incentives for energy efficiency and other sustainability issues in connection to renovation (papers I and II), factors that characterize firms with an ambitious approach to energy efficiency (paper V) and economic incentives for energy efficiency (paper VI). Developers’ behavior and impact on sustainability was studied in two ways: how developers’ planning and construction methods may influence energy consumption for future residents (paper III) and how developers relate to requirements for building environmental certification levels (paper IV). The first paper aims to clarify how housing firms see and treat energy efficiency matters in connection to renovation of multi-family buildings constructed during the 1960’s and 70’s. Interviews with housing firms resulted in four ideal housing firm types illustrating that housing firms have more or less incentives to improve energy efficiency. The second paper aimed to study a model for renovation of buildings in a residential area in peripheral Stockholm and to assess how it considers environmental, social and economic sustainability as well as technical concerns. Paper V builds on the results in paper I and aims to identify factors, on a firm level as well as in the surroundings of the firm, that characterize housing firms who own multi-family buildings from the 1960’s and 70’s and who have an ambitious approach to energy efficiency. Paper VI uses information from energy performance certificates to study whether better energy performance increases the selling price of single-family homes, which would increase owners’ incentives to improve energy efficiency. Paper III takes its starting point in an indicated shift in developers’ planning and construction practices for laundry facilities in owner-occupied multi-family buildings. The paper aims to clarify whether a shift has actually occurred from communal laundry rooms to in-unit laundry appliances and to illuminate the impact this could have on residents’ energy consumption for laundry. Paper IV reports the study of how developers who have adopted the environmental certification system LEED relate to the requirements for specific certification levels and how updated requirements risk undermining developers’ incentives for sustainable construction. / Den här avhandlingen sammanfattar arbetet från flera studier med koppling till hållbarhet inom bygg och förvaltning av fastigheter. Begreppet hållbarhet omfattar här tre dimensioner: miljömässig, social och ekonomisk hållbarhet, och fokus ligger på de aktörer som har mest möjlighet att påverka fastigheterna, nämligen fastighetsägare och projektutvecklare. I avhandlingen ingår sex uppsatser. Fastighetsägares uppfattning av och incitament och strategier för hållbarhet undersöktes på fyra olika sätt: incitament för energieffektivisering och andra hållbarhetsfrågor i samband med renovering (uppsats I och II), faktorer som karaktäriserar företag med ett ambitiöst förhållningssätt i energieffektiviseringsfrågor (uppsats V) samt ekonomiska incitament för energieffektivisering (uppsats VI). Projektutvecklares beteende och påverkan på hållbarhet undersöktes på två sätt: hur projektutvecklares planering och byggmetoder kan påverka energianvändningen för framtida boende (uppsats III) och hur projektutvecklare förhåller sig till kravnivåer i miljöcertifiering av byggnader (uppsats IV). Den första uppsatsen syftar till att belysa hur bostadsföretag ser på och behandlar energieffektiviseringsfrågor i samband med renovering av flerbostadshus byggda under miljonprogrammet. Baserat på intervjuer med bostadsföretag resulterade den explorativa studien i konstruktionen av fyra idealtyper av bostadsföretag med mer eller mindre incitament för att energieffektivisera. Den andra uppsatsen syftade till att undersöka en modell för renovering av miljonprogramshus i ett bostadsområde i Stockholms ytterområden och bedöma hur den tar hänsyn till miljömässig, social och ekonomisk hållbarhet tillsammans med tekniska överväganden. Uppsats V bygger på resultaten i uppsats I och syftar till att urskilja faktorer, såväl på företagsnivå som i företagets omgivning, som karaktäriserar bostadsföretag som äger flerbostadshus från miljonprogramsåren och som har en ambitiös hållning i energieffektiviseringsfrågor. Uppsats VI använder information från energideklarationer för att undersöka om bättre energiprestanda ökar försäljningspriset på småhus, något som skulle öka ägarens incitament för energieffektivisering. Uppsats III utgår från en indikerad förändring i projektutvecklares planering och byggmetoder av tvättinrättningar i flerbostadshus med bostadsrätt. Uppsatsen syftar till att klarlägga om en förändring har skett från gemensam tvättstuga till tvättmöjligheter i den egna bostaden och belysa vilken effekt det skulle kunna ha på de boendes energianvändning för tvätt. I uppsats IV klarläggs hur projektutvecklare som bygger enligt miljöcertifieringssystemet LEED förhåller sig till kraven för att uppnå nivåerna för att klassificeras och hur uppdaterade kravnivåer riskerar att undergräva projektutvecklarnas incitament för att bygga hållbart. / <p>QC 20141218</p>
433

Modeling and optimization for energy efficient large scale cooling operation

Kapoor, Kriti 17 February 2014 (has links)
Optimal chiller loading (OCL) is described as a means to improve the energy efficiency of a chiller plant operation. It is formulated as a multi-period constrained mixed integer non-linear optimization problem to optimize the total cooling load distribution through accurate chiller models. OCL is solved as a set of quadratic programs using sequential programming algorithm (SQP) in MATLAB. Based on application of the methodology to chiller systems at UT Austin and a semiconductor manufacturing facility, OCL can result in an annual energy savings of about 8%. However, the savings may reduce considerably in case of additional physical constraints on overall plant operation. With the addition of thermal energy storage (TES) to the system, OCL can reduce the daily cooling costs in the case of time varying electricity prices by 13.45% on an average. The energy efficiency of a chiller plant as a function of its chiller arrangement is studied by using fitted chiller models. If all other variables are kept same, chillers operating in parallel consume up to 9.62% less power as compared to when they are operated in series. Otherwise, chillers may operate up to 12.26% more efficiently in series depending on their chilled water outlet temperature values. The answer to the optimal chiller arrangement can be straightforward in some cases or can be a complex optimization problem in others. / text
434

Fate of the Houston skyline : stategies adopted for rehabilitating mid-century modern high-rises

Srinivasan, Urmila 08 July 2014 (has links)
A recent report by Terrapin Bright Green “Mid-century (Un) Modern” discusses the desperate condition of mid-century modern high-rises in Manhattan. The article argues that it would be beneficial both economically and environmentally to demolish these buildings and build new ones with an assumed increase in FAR. To re-build, repair or re-skin are the questions Mid-century Modern High-rises (MMH) face today. This study focuses on Houston, Texas, which is very different from New York City both climatically and from a planning stand point. It is dreaded for its hot and humid climate and notorious for its consistent refusal to adopt any zoning. These high-rises in Houston represent the economic success of the city immediately after WWII. These buildings were constructed as the city transformed from the Bayou City to the Space city. In this study I have mapped the status of these high-rises and the strategies that were used to renovate them. The questions I further wish to address are how preservation or energy efficiency are addressed while renovating these buildings. Even preservationists might agree that all buildings are not equal and a new look would benefit some. The real challenge lies in resolving the grey areas, where one is not talking about a Seagram or a Lever House, but a well designed environmentally sensitive building. / text
435

Design and evaluation of new search paradigms and power management for peer-to-peer file sharing

Perera, Graciela 01 June 2007 (has links)
Current estimates are that more than nine million PCs in the U.S. are part of peer-to-peer (P2P) file sharing overlay networks on the Internet. These P2P hosts generate about 20% of the traffic on the Internet and consume about 7.8 TWh/yr equal to $630 million per year. File search in a P2P network is based on a wasteful paradigm of broadcasting query messages. Reducing P2P overhead traffic to reduce bandwidth waste and enabling power management to reduce electricity usage are clearly of great interest. In this dissertation, two new search paradigms with reduced overhead traffic are investigated. The new Targeted Search method uses statistics from previous searches to target future searches. Targeted Search is shown to reduce query overhead traffic when compared to broadcast-based search used by Gnutella. The new Broadcast Updates with Local Look-up Search (BULLS) protocol enables new capabilities including power management and reduces overhead traffic by enabling a local look-up of shared files. BULLS hosts periodically broadcast changes in their list of files shared and build a table of shared files by all other hosts. Power management in P2P networks is studied as an application of the minimum set cover problem. A reduction in overall energy consumption is achieved by powering down hosts that have all of their shared files fully shared (or covered) by other hosts. A new set cover heuristic -- called the Random Map Out (RMO) algorithm --is introduced and compared to the well-known Greedy heuristic. The algorithms are evaluated for minimum set cover size and computational complexity (number of comparisons). The RMO algorithm requires significantly less comparisons than Greedy and still achieves a set cover size within a few percent of that of Greedy. Additionally, the RMO algorithm can be distributed and independently executed by each host with reduced complexity per host where the Greedy heuristic does not reduce in complexity by being distributed. With RMO there is a non-zero probability of a given file being "lost" (not in set cover). The probability of this event is modeled and numerical results show that the probability of a file being lost is practically insignificant.
436

Challenges and countermeasures of China's energy security

Yang, Fan, Wang, Dongcan January 2015 (has links)
To ensure energy security, the first to know what is energy, and second, what are the factors of non-security, means that the challenge of energy security. Finally, puts forward some policy or in the case of a reasonable method to solve it according to these problems. At present, energy security is facing two challenges of structural crisis and crisis management system. Concretely, main problems in that security are analyzed, which are considered to affect China and mostly embody in such four big areas as the great pressure in energy supply, the scarcity of relative energy resources, foreign oil dependence is too large, crisis management systems of energy security, the shortage of green energy. Furthermore the counter measures concerned are proposed, including saving energy and increasing the energy utilization rate, to establish strategic energy reserves, strengthening environmental protection and adjusting the primary energy structure. China's rapid economic growth lead to sharp increase in oil imports. Due to China relies on a single chokepoint, the Malacca Strait, which has caused a high degree of concern about the safety of its energy. Nearly three-quarters of its oil imports flowing through the Strait. In view of its strategic importance to China and China’s little sway on the waterway, this view is mainly focused on China’s energy demand and supply in two aspects of concern. The paper analysis of whether the current energy structure is appropriate and sustainable. Because the energy security is facing China's energy is more and more dependent on imported fuel and the need to convert energy to meet the demand of modern society and the rapid growth of the requirements of the economic challenges. Concludes that the China's new policy should focus on energy efficiency, energy saving, renewable energy and turned to the main energy source of natural gas.
437

Sustainable energy roadmap for Austin : how Austin Energy can optimize its energy efficiency

Johnston, Andrew Hayden, 1979- 18 February 2011 (has links)
This report asks how Austin Energy can optimally operate residential energy efficiency and demand side management programs including demand response measures. Efficient energy use is the act of using less energy to provide the same level of service. Demand side management encompasses utility initiatives that modify the level and pattern of electrical use by customers, without adjusting consumer behavior. Demand side management is required when a utility must respond to increasing energy needs, or demand, by its customers. In order to achieve the 20% carbon emissions and 800 MW peak demand reductions mandate of the Generation, Resource and Climate Plan, AE must aggressively pursue an increase in customer participation by expanding education and technical services, enlist the full functionality of a smart grid and subsequently reduce energy consumption, peak demand, and greenhouse gas emissions. Energy efficiency is in fact the cheapest source of energy that Austin Energy has at its disposal between 2010 and 2020. But this service threatens Austin Energy’s revenues. With the ascent of onsite renewable energy generation and advanced demand side management, utilities must address the ways they generate revenues. As greenhouse gas emissions regulations lurk on the horizon, the century-old business model of “spinning meters” will be fundamentally challenged nationally in the coming years. Austin Energy can develop robust analytical methods to determine its most cost-effective energy efficiency options, while creating a clear policy direction of promoting energy efficiency while addressing the three-fold challenges of peak demand, greenhouse gas emissions and total energy savings. This report concludes by providing market-transforming recommendations for Austin Energy. / text
438

Quantifying the economic and environmental tradeoffs of electricity mixes in Texas, including energy efficiency potential using the Rosenfeld effect as a basis for evaluation

Lott, Melissa Christenberry 16 February 2011 (has links)
Electricity is a complex and interesting topic for research and investigation. From a systems level, electricity includes many steps from its generation (power plants) to transmission and distribution to delivery and final use. Within each of these steps are a set of tradeoffs that are region-specific, depending heavily on the types of generation technologies and input fuels used to generate the electricity. These tradeoffs are complex and often not positively correlated to one another, producing a web of information that makes conclusions regarding the net benefit of changes to the electricity generation mix unobvious and difficult to determine using general rules of thumb. As individuals look to change the mix of technologies and fuels used to generate electricity for environmental or economic reasons, this complex web results in a lack of clarity and understanding of the consequences of particular choices. Quantitative tools could provide individuals with clear information and improved understanding of the tradeoffs associated with changes to the electricity mix. Unfortunately, prior to this research, no such tools existed that provided a clear, rigorous, and unbiased quantitative comparison of the region-specific environmental and economic tradeoffs associated with changes to the electricity mix. This research filled this gap by developing a methodology for calculating the environmental and economic impacts of changes to the electricity generation mix for individual regions. This methodology was applied specifically to Texas to develop the Texas Interactive Power Simulator (TIPS), an interactive online tool accessible via the internet. This tool is currently used for direct instruction at The University of Texas at Austin for undergraduate courses. Preliminary data were collected to determine the usefulness of this tool as a classroom aid. These data revealed that a majority of students enjoy using the TIPS tool, felt that they learned about the tradeoffs of electricity generation methods by using TIPS, and wish that there were more learning tools like TIPS available to them. This research also investigated the potential to use energy efficiency to satisfy a portion of the electricity demand that would otherwise be supplied using a generation technology. The methodology and series of decision criteria that were developed with this investigation were used to determine the amount of generation that could reasonably be satisfied with energy efficiency technologies and supportive policies for a particular region of interest, in this case Texas. This methodology was established using the Rosenfeld Effect as a basis for evaluating the energy efficiency potential in a specific region, providing a more realistic maximum energy efficiency value than using theoretical maximum gains based on current best available technology. It was then compared to efficiency potential estimates by the American Council for an Energy-Efficient Economy (ACEEE) and the Public Utility Commission of Texas (PUCT). In this research, I found that Texas is unlikely to realize more than an annual savings of 11% or about 1.5 megawatt-hours per capita compared to 2007 use levels based on nominal energy efficiency approaches. When this potential savings was applied to offset future demand increases in Texas, it was found that new generation capacity would still be needed over the next few decades to meet increasing total electricity demand. I used the economic and environmental tradeoff analysis and energy efficiency limitations methodologies that I established in my research to calculate the economic and environmental tradeoffs of changes to the electricity mix resulting from several scenarios, including federal energy and climate legislation, nuclear renaissance, high wind power growth, and maximizing energy efficiency. The outputs from these scenarios yielded the following observations: 1. Energy efficiency is unlikely to replace more than 11% of total per capita electricity demand in Texas. This level of energy efficiency might reduce total demand in the state, but population growth and its corresponding impacts on state electricity use might outpace the savings from energy efficiency in the long-term. This population growth could result in an overall increase in total annual state electricity use, despite energy efficiency gains. 2. While nuclear power might be environmentally advantageous from the standpoint of total emission of greenhouse gases compared to fossil fuel-fired power plants, it has very high up-front capital costs and is very water-intensive. 3. A federal combined energy efficiency and renewable portfolio standard might require states to install new renewable power generation capacity. In some states, including Texas, the amount of required new generation capacity may be small because of existing state initiatives encouraging renewable generation capacity to be installed in the state and the potential to offset some generation requirements using energy efficiency. / text
439

Essays on the optimal policy response to climate change

Kaufman, Noah 17 June 2011 (has links)
Unchecked anthropogenic climate change has the potential to destroy human lives and wealth on an unprecedented scale. This dissertation analyzes from an economic perspective various public policy options to correct the market failures caused by climate change. The widespread adoption of environmentally friendly consumer products can reduce the impacts of climate change. The first chapter analyzes various methods of encouraging the market performance of these products. I build a model of observational learning in which a "green" consumer good enters a market to challenge an established "dirty" product. Among other results, I provide conditions for when financial incentives or informational campaigns should be more effective at encouraging the market performance of green products. I also provide a discussion and an empirical analysis of the performance of compact fluorescent light bulbs in the U.S. residential market, and compare the findings to the predictions of the theoretical model. The second chapter provides a critic of the macroeconomic models economists have used to determine optimal climate change abatement policies. I build a model that can incorporate more realistic ranges of uncertainty for both the occurrence of catastrophic events and societal risk aversion than economists have used in the past. Numerical simulations are then used to calculate a range of risk premiums, the magnitude of which display that previous calculations of optimal carbon dioxide taxes are too imprecise to support any particular policy recommendation. Government-backed energy-efficiency programs have become popular as components of local and national strategies to combat climate change. The effectiveness of such policies hinges on whether they provide the appropriate incentives to both energy consumers and program implementers. The third chapter analyzes evaluations of California's energy-efficiency programs to assess their effectiveness at improving our understanding of the programs' performance and providing a check on utility incentives to overstate energy savings. We find, among other results, that evaluations are useful tools to achieve both of these goals because the programs largely did not meet their energy-savings projections, and the utility savings estimates are systematically higher than the third-party savings estimates of the evaluations. / text
440

The Case For Hardware Overprovisioned Supercomputers

Patki, Tapasya January 2015 (has links)
Power management is one of the most critical challenges on the path to exascale supercomputing. High Performance Computing (HPC) centers today are designed to be worst-case power provisioned, leading to two main problems: limited application performance and under-utilization of procured power. In this dissertation we introduce hardware overprovisioning: a novel, flexible design methodology for future HPC systems that addresses the aforementioned problems and leads to significant improvements in application and system performance under a power constraint. We first establish that choosing the right configuration based on application characteristics when using hardware overprovisioning can improve application performance under a power constraint by up to 62%. We conduct a detailed analysis of the infrastructure costs associated with hardware overprovisioning and show that it is an economically viable supercomputing design approach. We then develop RMAP (Resource MAnager for Power), a power-aware, low-overhead, scalable resource manager for future hardware overprovisioned HPC systems. RMAP addresses the issue of under-utilized power by using power-aware backfilling and improves job turnaround times by up to 31%. This dissertation opens up several new avenues for research in power-constrained supercomputing as we venture toward exascale, and we conclude by enumerating these.

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