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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.
1

Development of new methodologies for evaluating the energy performance of new commercial buildings

Song, Suwon 02 June 2009 (has links)
The concept of Measurement and Verification (M&V) of a new building continues to become more important because efficient design alone is often not sufficient to deliver an efficient building. Simulation models that are calibrated to measured data can be used to evaluate the energy performance of new buildings if they are compared to energy baselines such as similar buildings, energy codes, and design standards. Unfortunately, there is a lack of detailed M&V methods and analysis methods to measure energy savings from new buildings that would have hypothetical energy baselines. Therefore, this study developed and demonstrated several new methodologies for evaluating the energy performance of new commercial buildings using a case-study building in Austin, Texas. First, three new M&V methods were developed to enhance the previous generic M&V framework for new buildings, including: 1) The development of a method to synthesize weathernormalized cooling energy use from a correlation of Motor Control Center (MCC) electricity use when chilled water use is unavailable, 2) The development of an improved method to analyze measured solar transmittance against incidence angle for sample glazing using different solar sensor types, including Eppley PSP and Li-Cor sensors, and 3) The development of an improved method to analyze chiller efficiency and operation at part-load conditions. Second, three new calibration methods were developed and analyzed, including: 1) A new percentile analysis added to the previous signature method for use with a DOE-2 calibration, 2) A new analysis to account for undocumented exhaust air in DOE-2 calibration, and 3) An analysis of the impact of synthesized direct normal solar radiation using the Erbs correlation on DOE-2 simulation. Third, an analysis of the actual energy savings compared to three different energy baselines was performed, including: 1) Energy Use Index (EUI) comparisons with sub-metered data, 2) New comparisons against Standards 90.1-1989 and 90.1-2001, and 3) A new evaluation of the performance of selected Energy Conservation Design Measures (ECDMs). Finally, potential energy savings were also simulated from selected improvements, including: minimum supply air flow, undocumented exhaust air, and daylighting.
2

Building Archetype Development for Urban-Scale Energy Simulation of Existing City Districts : A study of the city of Uppsala

Dahlström, Lukas January 2020 (has links)
In this master thesis, a methodology is proposed for building stock classification and archetype building development based on deterministic information available in Energy Performance Certificates (EPCs) of existing buildings in the city of Uppsala.This study aims to answer if the EPC database can be used as a reliable data source for archetype development and further UBEM models.The EPC data is cleaned and organised using Matlab. The building stock is then categorised into archetypes by energy performance and building characteristics and a model of each archetype building is created in the software EnergyPlus.The South-West part of Uppsala is used as a case study and to represent the building stock of that area 20 archetypes is developed. Simulations in EnergyPlus shows that the defined archetypes is a reliable estimation of buildings in Sweden with the same characteristics and construction period.By using GIS data the results can be aggregated to city level with the resulting total energy demand for heating calculated to 1455,7 GWh, compared to the actual value of 1397,0 GWh.The lack of validation data on a smaller scale is a large issue for this study, as well as some issues with data reliability in the EPCs. Despite this, the results of this study points to that the gathered values are a decent enough estimate to make a reliable assumption of the total energy demand for heating. The EPCs thus provide a useful source of data for energy demand purposes and building characteristics.
3

En analys av EPC som modell för energieffektivisering : En djupdykning i energieffektiviseringsåtgärder i Umeå kommuns EPC-projekt för att närmare förstå EPC som projektform vid energieffektivisering

Öhrling, Jenny January 2015 (has links)
I detta examensarbete har åtgärder i ett energieffektiviseringsarbete av typen EPC analyserats. Umeå kommuns fastighetsavdelning startade sitt EPC-projekt 2008 syftet att energieffektivisera mer än 130 byggnader. Detta projekt sades då vara det största av sitt slag i Sverige. Bakgrunden till behovet av att utföra detta grundades i att en stor del av de tekniska systemens livslängd i fastigheterna började vara uppnådd samtidigt som ett energieffektiviseringskrav ålades fastighetsavdelningen. Siemens anlitades som entreprenör. De villkor som styrde projektet kom från beslutsfattande politiker och handlade om den viktiga besparingsgarantin. Denna garanti var en förutsättning för att få ekonomiska medel att finansiera ett projekt av den här storleken. EPC som modell valdes för att möjliggöra dessa krav. Den data som legat till grund för analysen av de energieffektiviseringsåtgärder som utförts har funnits samlad i eRoom, Siemens plattform för EPC-projekt. Den information som varit mest essentiell har varit de projektutvecklingsrapporter som för varje objekt beskrivit läge, problembild, åtgärdsförslag samt de energikartläggningar som innehållit alla energiberäkningar för energiläget i respektive fastighet samt potentiellt energiläge efter utförande av föreslagna åtgärder. De åtgärder som ansågs relevanta för att på det mest tydliga vis beskriva resultatet av Umeå EPC-projekt beslutades få ligga till grund för att reda ut hur besparingsfördelningen såg ut. Resultatet av detta arbete visar att de åtgärder som levererade störst del av den totala besparingen i ren energi var åtgärder kopplade till fläktar samt övriga åtgärder där styråtgärder av motorvärmare, injusteringar och pumpar rymdes. Efter dessa poster var tilläggsisolering samt belysningsåtgärder stora. Vidare vad gäller den ekonomiska besparingen var det konverteringar av uppvärmning som var absolut störst, därefter fläktarbeten samt kategorin övriga poster. Den ekonomiska investeringen var svår att på ett rättvist sätt jämföra mot hur stora besparingarna varit per åtgärd. En jämförelse av besparing mot antal åtgärder inom varje kategori visar däremot att konvertering till fjärrvärme samt värmeåtervinning var de mest effektiva åtgärderna.
4

Fastighetsmäklarens värdering av energieffektiviserande investeringar på småhusenheter

Pettersson, Jesper, Lidholm, Gustav January 2021 (has links)
The purpose of this study was to describe how real estate agents take into account invested energy improvement measures in their valuation of single-family homes. A qualitative research method has been used to achieve the purpose of the study. The data collection was performed through semi-structured interviews with real estate agents in Sweden. In order to be able to structure and analyze the collected material, an analysis method has been used according to Gioia. What we found in the study is that energy-saving investments affect value to varying degrees. Single measures have an insignificant value impact, while several investments have a greater effect on the value of the property. Investment in a new heating system is one such measure that we have found leads to an increased value. We have also found that there is a lack of market information for real estate agents when valuing single-family house units regarding to the energy performance of the comparison object.
5

Assessment and decision support for energy performance improvement of dwellings : framework and prototype development

Mhalas, Amit January 2013 (has links)
The target for carbon dioxide (CO2) emissions reduction in the UK is set at 20% by 2020 and 80% by 2050. The UK housing stock is one of the least energy efficient in Europe. The energy used in homes accounts for more than a quarter of energy use and carbon dioxide emissions in Great Britain. Therefore, it is imperative to improve the energy performance of the existing housing stock and fully exploit energy efficiency and renewable energy interventions. Several tools have been developed particularly in the last decade for energy assessment of dwellings, largely to inform policy development. However, when it comes to policy implementation stages, stakeholders such as local councils, energy suppliers, social housing providers and planners lack an effective tool, which assists them in estimating the potential for energy performance improvement through implementation of energy efficiency and renewable energy interventions. The UK government has several policies and initiatives to improve the energy performance of the housing stock. This research discusses the development of framework and a prototype tool to assist in implementation of these policies. There are a number of databases that hold information about the condition of the housing stock. This is in the form of digital maps, aerial and terrestrial imagery and statistics from census and housing surveys. This research presents an innovative way of integrating this information to undertake energy performance assessment on various geographical levels. The framework and the prototype allow stakeholders to determine the baseline energy performance of the dwellings based on their existing characteristics. This information is then used to estimate the potential for reduction in energy consumption and CO2 emissions and associated costs. Also integrated within the framework and the prototype is analytical hierarchy process based multi-criteria decision analysis technique that supports stakeholders in selection of energy performance improvement interventions suited to their requirements. Energy Performance Improvement of Dwellings Abstract Amit Mhalas, 2013 iv The developed framework and prototype are calibrated and validated with empirical data to determine the accuracy, reliability and trustworthiness. To demonstrate the practical applicability of the framework and the prototype, two separate case studies are undertaken involving the stakeholders. The results from the case studies indicate a potential to reduce CO2 emissions from dwellings by 70% through installation of energy performance improvement interventions. The developed framework and the prototype are expected to assist stakeholders in making informed decisions with regard to the implementation of energy policies and initiatives and contribute to meeting CO2 emission reduction targets.
6

Energideklarationer i flerbostadshus i Gävle

Ekbergh, Lina, Forss, Jenny January 2010 (has links)
Syfte: Syftet med uppsatsen är att undersöka hur energideklarationen har tagits emot och påverkat fastighetsägares arbete med energifrågor i flerbostadshus i Gävle. Metod: Denna uppsats baseras på kvalitativa intervjuer med fastighetsägare i Gävle. Fastighetsägarna som har medverkat är från den kommunala och privata hyressektorn samt kooperativa bostadsrättsorganisationer och privata bostadsrättsföreningar. Intervjumaterialet har sammanställts i fem olika kategorier i löpande text med förtydligande tabeller och diagram. Resultat och slutsats: Endast tre av de sju tillfrågade fastighetsägarna är helt färdiga med energideklarationerna. Alla respondenter anser att energideklarationen är bra över lag, men det finns även flera saker som de anser är negativt med energideklarationen. Majoriteten av respondenterna anser att de inte har gjort några större förändringar i och med den nya lagen, de jobbade redan med energibesparande åtgärder innan energideklarationerna genomfördes. Förslag till fortsatt forskning: I uppsatsen har vi inte tagit hänsyn till de boende och deras påverkan av energiförbrukningen. Intressant vore att undersöka hur fastighetsägarna kan påverka deras energiförbrukning och hur medvetna de boende är om sina vanor. Uppsatsens bidrag: Uppsatsen har gett en inblick i hur energideklarationen fungerar i verkligheten och hur den har tagits emot av fastighetsägare i Gävle. Vidare har uppsatsen bidragit till en överblick över vad de olika fastighetsägarna fokuserar på när det gäller energifrågor. Nyckelord: Energideklaration, energiförbrukning / Aim: The aim of this paper is to investigate how the Energy Performance Certificate have been received and have affected building owner’s work with energy related issues in residential buildings in Gävle.   Method: This paper is based on qualitative interviews with building owners in Gävle. The property owners who have contributed are from the municipal and private rental sector, co-operative economic associations and private housing cooperatives. The interview material has been put together in five different categories with clarifying tables and diagrams.   Result and conclusions: Only three out of seven building owners have completed the Energy Performance Certificates (EPC). All respondents generally think that the EPC is good, but there are several things that they consider negative about the EPC. The majority of the respondents think that they have not made any major changes with the new legislation; they already worked with energy-saving measures before the EPC was carried out.   Suggestions for future research: In the paper we have not considered the tenants and their influence on the energy consumption. It would be interesting to research how the building owners can affect their energy consumption and how aware they are of their habits.   Contribution of the thesis: The paper gives an insight in how the EPC works in reality and how it has been received by building owners in Gävle. Furthermore, the paper have contributed to a general view of what the building owners focus on when it comes to energy relates issues.   Key words: Energy Performance Certificate, Energy consumption
7

A Client-Centric Data Streaming Technique for Smartphones: An Energy Evaluation

Abogharaf, Abdulhakim 04 1900 (has links)
With advances in microelectronic and wireless communication technologies, smartphones have computer-like capabilities in terms of computing power and communication bandwidth. They allow users to use advanced applications that used to be run on computers only. Web browsing, email fetching, gaming, social networking, and multimedia streaming are examples of wide-spread smartphone applications. Unsurprisingly, network-related applications are dominant in the realm of smartphones. Users love to be connected while they are mobile. Streaming applications, as a part of network-related applications, are getting increasingly popular. Mobile TV, video on demand, and video sharing are some popular streaming services in the mobile world. Thus, the expected operational time of smartphones is rising rapidly. On the other hand, the enormous growth of smartphone applications and services adds up to a significant increase in complexity in the context of computation and communication needs, and thus there is a growing demand for energy in smartphones. Unlike the exponential growth in computing and communication technologies, the growth in battery technologies is not keeping up with the rapidly growing energy demand of these devices. Therefore, the smartphone's utility has been severely constrained by its limited battery lifetime. It is very important to conserve the smartphone's battery power. Even though hardware components are the actual energy consumers, software applications utilize the hardware components through the operating system. Thus, by making smartphone applications energy-efficient, the battery lifetime can be extended. With this view, this work focuses on two main problems: i) developing an energy testing methodology for smartphone applications, and ii) evaluating the energy cost and designing an energy-friendly downloader for smartphone streaming applications. The detailed contributions of this thesis are as follows: (i) it gives a generalized framework for energy performance testing and shows a detailed flowchart that application developers can easily follow to test their applications; (ii) it evaluates the energy cost of some popular streaming applications showing how the download strategy that an application developer adopts may adversely affect the energy savings; (iii) it develops a model of an energy-friendly downloader for streaming applications and studies the effects of the downloader's parameters regarding energy consumption; and finally, (iv) it gives a mathematical model for the proposed downloader and validates it by means of experiments.
8

HVAC operation uncertainty in energy performance gap

Wang, Yijia 21 September 2015 (has links)
This study aims at a preliminary characterization of system operation uncertainty. It bases this on an analysis of the energy consumption of 6 existing buildings on the Georgia Tech campus. The analysis is speculative in nature.
9

A Client-Centric Data Streaming Technique for Smartphones: An Energy Evaluation

Abogharaf, Abdulhakim 04 1900 (has links)
With advances in microelectronic and wireless communication technologies, smartphones have computer-like capabilities in terms of computing power and communication bandwidth. They allow users to use advanced applications that used to be run on computers only. Web browsing, email fetching, gaming, social networking, and multimedia streaming are examples of wide-spread smartphone applications. Unsurprisingly, network-related applications are dominant in the realm of smartphones. Users love to be connected while they are mobile. Streaming applications, as a part of network-related applications, are getting increasingly popular. Mobile TV, video on demand, and video sharing are some popular streaming services in the mobile world. Thus, the expected operational time of smartphones is rising rapidly. On the other hand, the enormous growth of smartphone applications and services adds up to a significant increase in complexity in the context of computation and communication needs, and thus there is a growing demand for energy in smartphones. Unlike the exponential growth in computing and communication technologies, the growth in battery technologies is not keeping up with the rapidly growing energy demand of these devices. Therefore, the smartphone's utility has been severely constrained by its limited battery lifetime. It is very important to conserve the smartphone's battery power. Even though hardware components are the actual energy consumers, software applications utilize the hardware components through the operating system. Thus, by making smartphone applications energy-efficient, the battery lifetime can be extended. With this view, this work focuses on two main problems: i) developing an energy testing methodology for smartphone applications, and ii) evaluating the energy cost and designing an energy-friendly downloader for smartphone streaming applications. The detailed contributions of this thesis are as follows: (i) it gives a generalized framework for energy performance testing and shows a detailed flowchart that application developers can easily follow to test their applications; (ii) it evaluates the energy cost of some popular streaming applications showing how the download strategy that an application developer adopts may adversely affect the energy savings; (iii) it develops a model of an energy-friendly downloader for streaming applications and studies the effects of the downloader's parameters regarding energy consumption; and finally, (iv) it gives a mathematical model for the proposed downloader and validates it by means of experiments.
10

Performance characterisation of photovoltaic devices : managing the effects of high capacitance and metastability

Eeles, Alexander January 2016 (has links)
It is essential to make performance measurements of photovoltaics modules in order to quantify the power they will produce under operational conditions. Performance measurements are fundamental throughout the photovoltaic industry, from product development to quality control in manufacturing and installation in the field. Rapid and economic evaluation of photovoltaic performance requires measurements using pulsed illumination solar simulators. However some devices have characteristics which can cause difficulties making these measurements. The aim of this thesis is to overcome these measurement problems focusing particularly on two of the most prevalent and pressing of these problematic characteristics: high capacitance and metastability. A new method for measuring high capacitance modules in a pulsed simulator, based on tailor made voltage ramps, was developed. The voltage ramp is tailor made such that the measurement time is minimised while maintaining high accuracy (0.5 %), allowing the measurement of high capacitance modules in a single 10ms illumination pulse. The necessary inputs for this method are the capacitance and dark current as a function of voltage for each module. In order to make these measurements, at the high forward bias voltages required, a new system was developed. The tailored voltage ramp can be created individually for each module, since the process is rapid an automatic. This makes the method applicable to a production line or to test house measurements. In addition to their use as inputs for the voltage ramp design, the capacitance and dark current also contain other valuable information, including effective minority carrier lifetime. In several thin film technologies, such as CIGS, the efficiency is not a fixed value, rather the module is metastable and the efficiency changes depending on the previous exposure /preconditioning of the device. Preconditioning is normally applied to these devices before measurement in order to put them in a specific state that is repeatable and representative of outdoor operation. Improved preconditioning practices are vital for performance measurements in CIGS modules. Therefore the preconditioning behaviour of a variety of CIGS modules from different manufacturers was investigated. The effect of preconditioning varied for different modules, commonly the fill factor improved substantially, but often changes in open circuit voltage were also seen and in some cases also substantial changes in short circuit current. The rates of preconditioning and relaxation were found to follow stretched exponential behaviour, such that the changes occur linearly on a logarithmic timescale over several orders of magnitude in time. The total time for performance stabilisation was found to vary significantly between different types of module. Because of this stretched exponential behaviour, even though the module took days to fully relax to the dark state, there was significant relaxation within the tens of minutes that it would normally take a module to cool down after light soaking before it could be measured. The major implication of observed kinetics is that in order to achieve repeatable measurement the timing in each element of a preconditioning routine should be controlled such that the fractional error in the duration of each step is small. During the investigation an unexpectedly short timescale preconditioning effect was observed, which occurs on a millisecond timescale and relaxes in seconds. It was shown that the measurement artefacts introduced using this method can be eliminated by using electrical forward bias until immediately before the measurement. Another measurement system was developed to track the dark current and C-V characteristic of the modules during electrical bias preconditioning and subsequent relaxation. These measurements demonstrate that more than one process involved during preconditioning in CIGS. Changes occur both in the doping in the bulk of the absorber and also in charge accumulation occurring near to the absorber / buffer interface. The theoretical models for preconditioning in CIGS were reviewed and compared to the experimental results. A rate model was developed based on the theory of the metastable VSe-VCu defect. This model was shown to correspond well to the rates of preconditioning and relaxation in CIGS. The non-exponential behaviour was shown to be compatible with a distribution of activation energies for the transition between different defect states. The difference in the time taken for modules to stabilise is explained by differences in doping density and the density of VSe-VCu defects. The work presented facilitates more accurate, economical performance measurements for high capacitance devices and CIGS devices, thereby contributing to the large scale implementation of photovoltaics as power source.

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