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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

The Role of Comparative Electricity Use Feedback at the Building Level in University Research Buildings

Ma, Daghoo 03 June 2013 (has links)
University research buildings are significant energy consumers in the United States. There is therefore a need to reduce energy use on the nation's campuses, not only cutting their carbon footprints but also saving money. Universities' efforts to reduce energy use include updating older facilities, implementing renewable energy systems, and encouraging energy saving behavior. This study evaluated the differential effects of two forms of feedback on electricity consumption in two groups of research buildings on a college campus to determine whether providing feedback to energy users has an impact on energy conservation behavior. A control group of buildings received no feedback regarding their electricity use. In the first study group of buildings, occupants received information about their electricity consumption with some electricity saving tips, distributed via email. The same procedure was followed with building occupants in the second study group, who received additional information showing their electricity consumption performance in comparison to other buildings within the study group. The baseline reading was conducted a week before the experiment began in August, 2012. Over the course of the five week study, the daily adjusted average reductions in electricity usage compared to the control group were less than 1 percent for both study groups, with study group 1 achieving an average reduction of 0.2 percent and study group 2 an average reduction of 0.8 percent. Although the reduction observed for study group 2 was 4 times greater than that for study group 1, the saving was not continuous over the study period. Accordingly, the result was deemed to be not statistically significant and the effectiveness of comparative energy use feedback in university research buildings was not supported. However, even small savings in the energy used in university research buildings can be very important in terms of the total amount of energy saved because research buildings use significantly more energy than other buildings on campus such as academic buildings and residence blocks. This study concludes with a consideration of potentially fruitful directions for future research into developing new ways to reduce the energy consumption on university campuses. / Master of Science
2

Distributed Photovoltaics, Household Electricity Use and Electric Vehicle Charging : Mathematical Modeling and Case Studies

Munkhammar, Joakim January 2015 (has links)
Technological improvements along with falling prices on photovoltaic (PV) panels and electric vehicles (EVs) suggest that they might become more common in the future. The introduction of distributed PV power production and EV charging has a considerable impact on the power system, in particular at the end-user in the electricity grid. In this PhD thesis PV power production, household electricity use and EV charging are investigated on different system levels. The methodologies used in this thesis are interdisciplinary but the main contributions are mathematical modeling, simulations and data analysis of these three components and their interactions. Models for estimating PV power production, household electricity use, EV charging and their combination are developed using data and stochastic modeling with Markov chains and probability distributions. Additionally, data on PV power production and EV charging from eight solar charging stations is analyzed. Results show that the clear-sky index for PV power production applications can be modeled via a bimodal Normal probability distribution, that household electricity use can be modeled via either Weibull or Log-normal probability distributions and that EV charging can be modeled by Bernoulli probability distributions. Complete models of PV power production, household electricity use and EV home-charging are developed with both Markov chain and probability distribution modeling. It is also shown that EV home-charging can be modeled as an extension to the Widén Markov chain model for generating synthetic household electricity use patterns. Analysis of measurements from solar charging stations show a wide variety of EV charging patterns. Additionally an alternative approach to modeling the clear-sky index is introduced and shown to give a generalized Ångström equation relating solar irradiation to the duration of bright sunshine. Analysis of the total power consumption/production patterns of PV power production, household electricity use and EV home-charging at the end-user in the grid highlights the dependency between the components, which quantifies the mismatch issue of distributed intermittent power production and consumption. At an aggregate level of households the level of mismatch is shown to be lower.
3

Energy Audit and Energy Saving Measures of a Large Office Building : Bern 9 in Örnsköldsvik

Björklund, Lina January 2020 (has links)
There is a large potential in making the residential and service sector more energy efficient and the first step towards achieving a more efficient use of energy is to implement an energy audit. In this study a property with an approximate area of 8 000 m2, consisting of a main building and three building extensions from different eras has been examined. The main building and its extensions were built in different stages and the first one in the early 20th century and some parts of the last building extension were modified at the time that the examination was carried out. This indicates that there is a vast energy savings potential in the property and an energy audit was performed. The main aim of the study was to examine where the energy was being used and where energy could be saved. Energy saving measures has been suggested together with a calculated approximate energy decrease and payback period. The total energy savings potential for the measures is approximately 146 MWh. The energy audit showed that a large amount of electricity was being used during non-work hours and that energy was lost through the building envelope. The electricity use during non-work hours was examined during the night walk, however, it is suggested to carry out further examinations regarding the property’s vast electricity use during non-work hours. To add loose wool in the roof of B2 has an energy savings potential of 33 000 kWh/year. Another measure is to clean the heat exchangers, this measure has an energy savings potential of 26 000 kWh/year. Also it is suggested to optimize the operational hours for the lighting by implementing presence control and to decrease the energy use for ventilation by cleaning the heat exchangers. Further examinations that would improve the study would be to do measurements of the electricity and temperatures to get a better understanding of the buildings energy use. Also to model the building in a simulation tool would give a calculated energy loss that is more like the actual energy loss of the building and make the results more reliable.
4

Livscykelanalys av det vertikala odlingssystemet Freja : En fallstudie i samarbete med Swegreen med fokus på att finna miljöpåverkans- hotspots

Brandel, Andrea, Borgström, Nora January 2024 (has links)
Livsmedelsindustrin är en bidragande faktor till klimatförändringarna, där innovativalösningar, såsom vertikal odling, kan appliceras för att främja en hållbar livsmedelsproduktion. Vertikala odlingssystem möjliggör urban inomhusodling,vertikalt i hyllplan, i kontrollerade miljöer med odlingskammare, belysningssystem samt vanligtvis jordfri odlingsmetod (t.ex. hydroponik), som är essentiella delar avsystemet. Temperatur, relativ fuktighet och artificiellt ljus regleras efter grödornas behov. Vid hydroponisk odling används odlingssubstrat såsom stenull istället för jord och växternas rötter är i konstant kontakt med det återcirkulerande vattnet i systemet, som förser växterna med näring. Tidigare livscykelanalyser av vertikala odlingssystem, om än ett begränsat antal, belyser elförbrukningen som den största bidragande faktorn till miljöpåverkan, samt att utbyte av olika material kan generera en lägre total miljöpåverkan. Examensarbetet syftar till att utföra en livscykelanalys på Swegreens vertikala odlingssystemet Freja, på ICA Maxi i Solna. Vidare syftar livscykelanalysen till att identifiera de faser och flöden som står för betydande miljöpåverkan, samt några förbättringsförslag. Det vertikala odlingssystemet antar perspektivet ‘vagga till användning’ under 30 år, exkluderande monterings- och sluthanteringsfasen. Användningsfasen innefattar sallatens livscykel från ‘vagga till grav’, exkluderande förtäringsfasen. Den funktionella enheten är 1 kg producerad ekbladssallat tillgänglig för konsumenter av klass 1. Data har inhämtats från både Swegreens digitaliserade data och från en tidigare studie utförd på Swegreens odlingssystem Saga. För bearbetning har programvaran SimaPro och databasen Ecoinvent 3.8 använts. Resultaten analyseras utifrån miljöpåverkanskategorierna ekotoxicitet (sötvatten), fossil resursanvändning, försurning, klimatförändringar, markanvändning, resursanvändning (mineraler och metaller), vattenanvändning och övergödning (sötvatten). Odlingsfasen för sallaten (innehållande elanvändning) är systemets främsta hotspot, följt av råmaterialsfasen för sallat, som orsakar störst miljöpåverkan för samtliga miljöpåverkanskategorier, förutom för resursanvändning (mineraler och metaller). Resultaten kan ej generaliseras eftersom de beror på val av funktionell enhet, systemgränser samt typ av data. Resultaten från känslighetsanalysen för energiproduktion och sluthantering tyder på att olika scenarion genererar lägst miljöpåverkan, beroende på vilka miljöpåverkanskategorier som anses mest relevanta. / The food industry is a contributing factor to climate change, where innovative solutions, such as vertical farming, can be applied to promote sustainable food production. Vertical farming systems enable urban indoor farming, vertically on shelves, in controlled environments with cultivation chambers, lighting systems and usually soil-free cultivation methods (e.g. hydroponics), that are essential parts of the system. Temperature, relative humidity and artificial light are regulated to satisfy the crops needs. Hydroponic cultivation utilizes growing mediums such as rock wool instead of soil and the roots of the plants are in constant contact with the recirculating water in the system, which provides the plants with nutrients. Previous life cycle assessments of vertical farming systems, although limited in numbers,highlight the electricity consumption as the largest contributing factor to the environmental impact, as well as replacing different materials for a lower environmental impact. This study aims to assess the environmental impacts and hot spots, through the use of life cycle assessment, on Swegreen's vertical farming system Freja, at ICA Maxi Solna. Furthermore the life cycle assessment aims to identify the phases and flows that accounts for significant environmental impact, as well as some suggestions for improvement. The vertical farming system applies the perspective of ‘cradle to use’for 30 years, not including the assembly or waste disposal phase. The use phase includes the life cycle of lettuce, from ‘cradle to grave’, not including the consumption phase. The functional unit is 1 kg of produced oak leaf lettuce, class 1,available to consumers. Data has been obtained from both Swegreen's digitized data and from a previous study conducted on Swegreen's farming system Saga. To process the data, the software SimaPro and the Ecoinvent 3.8 database was applied. Results are analyzed with regards to the environmental impact categories ecotoxicity (freshwater), fossil resource use, acidification, climate change, land use,resource use (minerals and metals), water use and eutrophication (freshwater).Results indicate that the lettuce cultivation phase (containing electricity use) is the main hotspot of the system, followed by the raw material phase for the lettuce. Aphase that also dominates in all environmental impact categories, except for resource use (minerals and metals). Results cannot be generalized since they dependon the choice of functional unit, system boundaries and type of data. The sensitivity analysis regarding the energy production and waste disposal suggests that different alternatives cause the lowest environmental impact, depending on which environmental impact categories are considered the most important.
5

The rhythm of life is a powerful beat : demand response opportunities for time-shifting domestic electricity practices

Higginson, Sarah L. January 2014 (has links)
The 2008 Climate Change Act set legally-binding carbon reduction targets. Demand side management (DSM) includes energy use reduction and peak shaving and offers significant potential to reduce the amount of carbon used by the electricity grid. The demand side management (DSM) schemes that have tried to meet this challenge have been dominated by engineering-based approaches and so favour tools like automation (which aims to make shifting invisible) and pricing (which requires customer response) to shift demand. These approaches tend to focus on the tools for change and take little account of people and energy-use practices. This thesis argues that these approaches are limited and therefore unlikely to produce the level of response that will be needed in future. The thesis therefore investigates the potential for time-shifting domestic energy demand but takes a different angle by trying to understand how people use energy in their daily lives, whether this use can be shifted and some of the implications of shifting it. The centrepiece of the work is an empirical study of eleven households energy-use practices. The interdisciplinary methodology involved in-house observations, interviews, photographs, metered energy data and disruptive interventions. The data was collected in two phases. Initially, a twenty-four hour observation was carried out in each household to find out how energy was implicated in everyday practices. Next, a series of three challenges were carried out, aimed at assessing the implications of disrupting practices by time-shifting food preparation, laundry and work/ leisure. A practice theory approach is used to shift the focus of attention from appliances, tools for change, behaviour or even people, to practices. The central finding of this work is that practices were flexible. This finding is nuanced, in the light of the empirical research, by an extended discussion on the nature of practices; in particular, the relationship between practices and agency and the temporal-spatial locatedness of practices. The findings demonstrate that, in this study at least, expanding the range of demand response options was possible. The research suggests numerous possibilities for extending the potential of practices to shift in time and space, shift the energy used in practices or substitute practices for other non-energy-using practices, though there are no simple technological or behavioural fixes . More profoundly, however, the thesis concludes that infrastructures of provision , such as the electricity grid and the companies that run it, underpin and facilitate energy-use practices irrespective of the time of day and year. In this context technology-led demand response schemes may ultimately contribute to the problem they purport to solve. A more fundamental interrogation of demand and the infrastructures that serve it is therefore necessary and is almost entirely absent from the demand response debate.
6

Synergy between Residential Electric Vehicle Charging and Photovoltaic Power Generation through Smart Charging Schemes : Models for Self-Consumption and Hosting Capacity Assessments

Fachrizal, Reza January 2020 (has links)
The world is now in a transition towards a more sustainable future. Actions to reduce the green-house gases (GHG) emissions have been promoted and implemented globally, including switching to electric vehicles (EVs) and renewable energy technologies, such as solar photovoltaics (PV). This has led to a massive increase of EVs and PV adoption worldwide in the recent decade. However, large integration of EVs and PV in buildings and electricity distribution systems pose new challenges such as increased peak loads, power mismatch, component overloading, and voltage violations, etc. Improved synergy between EVs, PV and other building electricity load can overcome these challenges. Coordinated charging of EVs, or so-called EV smart charging, is believed to a promising solution to improve the synergy. This licentiate thesis investigates the synergy between residential EV charging and PV generation with the application of EV smart charging schemes. The investigation in this thesis was carried out on the individual building, community and distribution grid levels. Smart charging models with an objective to reduce the net-load (load - generation) variability in residential buildings were developed and simulated. Reducing the net-load variability implies both reducing the peak loads and increasing the self-consumption of local generation, which will also lead to improved power grid performance. Combined PV-EV grid hosting capacity was also assessed.       Results show that smart charging schemes could improve the PV self-consumption and reduce the peak loads in buildings with EVs and PV systems. The PV self-consumption could be increased up to 8.7% and the peak load could be reduced down to 50%. The limited improvement on self-consumption was due to low EV availability at homes during midday when the solar power peaks. Results also show that EV smart charging could improve the grid performance such as reduce the grid losses and voltage violation occurrences. The smart charging schemes improve the grid hosting capacity for EVs significantly and for PV slightly. It can also be concluded that there was a slight positive correlation between PV and EV hosting capacity in the case of residential electricity distribution grids.

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