The amount of distributed generation (DG) is increasing worldwide, and it is located in distribution networks close to consumers or even in the consumers¡¦ side of the meter. Therefore, the net demand to be supplied through transmission and distribution networks may decrease, allowing to postpone reinforcement of existing networks. This thesis presents a methodology for assessing the potential benefits of using non--constructional reinforcement strategies to relieve distribution network congestion and increase the utilization of the network assets. Due to the randomness of involved variables (load demand patterns, DG hourly production, DG availability, etc.), a simulation approach is used to model the uncertainties. The benefits of DG, energy storage (ES), and demand response (DR) on congestion relief and investment deferment are evaluated. The analyzed items include: the distribution network investment avoided cost, levelized annual cost, hourly overload probability, and hourly overload risk. Simulation results indicate the potential benefits of non--traditional strategies in increasing the distribution network utilization and relieving network congestion.

Residential buildings in the United States are responsible for the consumption of 38% of electricity, and for much of the fluctuations in the power demands on the electric grid, particularly in hot climates. Residential buildings are also where occupants spend nearly 69% of their time. As “smart” technologies, including electric grid-connected devices and home energy management systems are increasingly available and installed in buildings, this research focuses on the use of these technologies combined with available energy use data in accomplishing three main objectives. The research aims to: (a) better understand how residential buildings currently use electricity, (b) evaluate the use of these smart technologies and data to reduce buildings’ electricity use and their contribution to peak loads, and (c) develop a methodology to assess the impacts of these operational changes on occupant thermal comfort. Specifically this study focuses on two of the most significant electricity consumers in residential buildings: large appliances, including refrigerators, clothes washers, clothes dryers and dishwashers, and heating, ventilation and air conditioning (HVAC) systems. First, to develop an improved understanding of current electricity use patterns of large appliances and residential HVAC systems, this research analyzes a large set of field-collected data. This dataset includes highly granular electricity consumption information for residential buildings located in a hot and humid climate. The results show that refrigerators have the most reliable and consistent use, while the three user-dependent appliances varied more greatly among houses and by time-of-day. In addition, the daily use patterns of appliances vary in shape depending on a number of factors, particularly whether or not the occupants work from home, which contrasts with common residential building energy modeling assumptions. For the all-air central HVAC systems studied, the average annual HVAC duty cycle was found to be approximately 20%, and varied significantly depending on the season, time of day, and type of residential building. Duty cycle was also correlated to monthly energy use. This information provides an improvement to previously assumed values in indoor air modeling studies. Overall, the work presented here enhances the knowledge of how the largest consumers of residential buildings, large appliances and HVAC, operate and use energy, and identifies influential factors that affect these use patterns. The methodologies developed can be applied to determine use patterns for other energy consuming devices and types of buildings, to further expand the body of knowledge in this area. Expanding on this knowledge of current energy use, smart large appliances and residential HVAC systems are investigated for use in reducing peak electric grid loads, and building energy use, respectively. This includes a combination of laboratory testing, field-collected data, and modeling. For appliance peak load reduction, refrigerators are found to have a good demand response potential, in part due to the nearly 100% of residential buildings that have one or more of these appliances, and the predictability of their energy consumption behavior. Dryers provide less consistent energy use across all homes, but have a higher individual peak power demand during afternoon and evening peak use times. These characteristics also make dryers also a good candidate for demand response. The study of continuous commissioning of HVAC systems using energy data found that both runtime and energy use are increased, and cooling capacity and efficiency are reduced due to the presence of faults or inefficiencies. The correction of these faults have an estimated 1.4% to 5.7% annual impact on a residential building’s electricity use in a cooling-dominated climate such as the one studied. Overall, appliance peak load reduction results are useful for utility companies and policy makers in identifying what smart appliance may provide the most peak energy reduction potential through demand response programs. The results of the HVAC study provides a methodology that can be used with energy use data, to determine if an HVAC system has the characteristics implying an inefficiency may be present, and to quantify the annual savings resulting from its correction. The final aspect of this research focuses on the development of a tool to enable an assessment the effect of operational changes of a building associated with energy and peak load reduction on occupant comfort. This is accomplished by developing a methodology that uses the response surface methodology (RSM), combined with building performance data as input, and uncertainly analysis. A second-order RSM model constructed using a full-factorial design was generally found to provide strong agreement to in and out-of-sample building simulation data when evaluating the Average Percent of People Dissatisfied (PPD[subscript avg]). This 5-step methodology was applied to assess occupant thermal comfort in a residential building due to a 1-hour demand response event and a time-of-use pricing rate schedule for a variety of residential building characteristics. This methodology provides a model that can quickly assess, over a continuous range of values for each of the studied design variables, the effect on occupant comfort. This may be useful for building designers and operators who wish to quickly assess the effect of a change in building operations on occupants. / text

South African cement manufacturers are under financial pressure. Sales have declined due to the 2008 recession and electricity costs have tripled from 2005 to 2012. Electricity cost savings are therefore more important than ever. Unfortunately retrofitting highly energyefficient equipment is not ideal. These installations are costly and take a long time to implement. Alternative strategies that can produce quick results in reducing electricity costs are needed. One such alternative is a programme called Demand Market Participation (DMP). The DMP programme was implemented by Eskom, South Africa’s national electricity utility, to reduce electricity demand during supply shortages. This programme offers potential cost savings for clients with excess production capacity. Clients such as cement plants can switch off non-essential production equipment in Eskom’s peak demand periods for a financial incentive. To maximise the benefits for both the clients and Eskom, accurate electricity forecasting is needed, as are systems enabling a quick response to load reduction requests. In this study DMP opportunities on typical cement plants were identified. A DMP strategy to assist cement plants was developed to achieve maximum cost savings without influencing production, quality and safety. An existing energy management system (EnMS) was adapted to incorporate the new DMP participation strategy. The new EnMS and DMP strategy were implemented at a South African cement plant, resulting in savings of R220 000 per month. This translates into an annual cost-saving potential of R2-million for the plant, and an R13- million cost-saving potential for the total South African cement industry. / MIng (Mechanical Engineering), North-West University, Potchefstroom Campus, 2014

Este trabalho apresenta o desenvolvimento de uma técnica construtiva inédita para dutos enterrados intitulada Geovala. Esta técnica consiste na instalação de um geossintético sobre uma vala, preenchida ou não com material fofo, localizado acima do duto com o principal objetivo de reduzir os esforços que atingem a estrutura. Para contribuir na avaliação do sistema proposto foi realizado um programa de ensaios em pequenas e grandes dimensões no laboratório de geossintéticos da Escola de Engenharia de São Carlos EESC/USP. Neste programa de ensaios foi possível verificar que o sistema Geovala pode reduzir drasticamente as tensões na parede do duto e na envoltória de solo ao redor do duto. Além disso, um método analítico foi proposto para prever os deslocamentos verticais, deformações e esforços de tração gerados no geotêxtil, durante o rocesso construtivo e sobrecarga. Finalmente, verificou-se que os deslocamentos do geotêxtil previstos pelo método foram similares aos deslocamentos registrados nos ensaios experimentais. / This thesis presents the development of an unpublished constructive technique for buried pipes entitled Geovala. This technique comprises of the installation of a geosynthetic over a trench, filled or not with soft material, located above the pipe with the main objective of reducing the loads on the structure. To evaluate the proposed technique small and large scale testing programs were carried out at the laboratory of geosynthetics of the School of Engineering at Sao Carlos EESC/USP. In this testing program it was possible to verify that the Geovala system can reduce drastically the loads on the walls of the pipe and in the surrounding soil. Besides, an analytical method was proposed to predict the vertical displacement, deformations and tensile stress on the geosynthetic, during the constructive process and surcharge. Finally, it was verified that the displacements of the geotextile predicted by the analytical method were similar to the displacements recorded in the experimental tests.

A rapid growth in the national electricity demand is placing an ever-increasing demand on the national electricity supply utility, Eskom. Projections show that the load demand in South Africa may exceed the installed capacity by as early as 2007. This is mainly due to the increase in demand in the residential sector as a result of the electrification of rural and previously disadvantaged communities. However, the industrial and commercial sectors also have a role in this increase. In an attempt to reduce the demand for electricity Eskom has adopted its Demand Side Management (DSM) initiative. This initiative is aimed at lowering the electricity demand in peak times through energy efficiency (EE) or load shift, out of peak demand times. Eskom is implementing the DSM strategy by financing Energy Service Companies (ESCOs) to reduce the demand load of major electricity end-users during peak times. Buildings consume a large percentage of the total energy supply in the world. Most of the energy consumed in buildings is used by the heating, ventilation and air-conditioning (HVAC) systems, as well as lighting. However, a large potential for energy savings exists in buildings. Studies have shown that up to 70% of the electricity consumption of a building can be saved through retrofit studies. However, to capitalise on these opportunities, the ESCOs require tools and procedures that would enable them to accomplish energy savings studies quickly and efficiently. It should be a holistic approach to the typical ESCO building audit. A study of current available software programs showed the lack of holistic tools aimed specifically at retrofit audits, and therefore also the need for such a program. The building simulation program most suited to the retrofit study was chosen and it was used in a retrofit audit. By emulating a retrofit audit with this software, its performance in the field, both positive and negative, could be established. With the experience gained from the retrofit study, as well as input from ESCOs in the industry, a need for such a retrofit tool was established. The simulation program that was tested in the retrofit study is the tool Quickcontrol, as well as the newer version of the program, entitled QEC. The case study showed that even though these packages are well suited to ESCO work, they have certain drawbacks in view of the holistic project approach. The ESCOs require a simple, fast, and integrated procedure for energy audits. This procedure should be embodied in a software program. This study proposes a new integrated procedure for energy audits and the analyses of buildings, in the form of a software tool. This new tool is geared towards the ESCO building audit, in both South A6ica and internationally. It is designed to enable a diplomate engineer to accomplish a building energy and retrofit analysis in two weeks, leading the user through all the main project steps, from data acquisition to writing of the final project report. This is a significant improvement, since it normally takes 50 man-days for an experienced and trained engineering team to complete a full building audit. This tool was used in a case study to test its validity and accuracy. It was found that certain situations would arise in which the criteria that were set for the program would not be adequate. The results from the case study were favourable and satisfied the criteria that were set for the procedure. / Thesis (Ph.D. (Mechanical Engineering))--North-West University, Potchefstroom Campus, 2004.

South African cement manufacturers are under financial pressure. Sales have declined due to the 2008 recession and electricity costs have tripled from 2005 to 2012. Electricity cost savings are therefore more important than ever. Unfortunately retrofitting highly energyefficient equipment is not ideal. These installations are costly and take a long time to implement. Alternative strategies that can produce quick results in reducing electricity costs are needed. One such alternative is a programme called Demand Market Participation (DMP). The DMP programme was implemented by Eskom, South Africa’s national electricity utility, to reduce electricity demand during supply shortages. This programme offers potential cost savings for clients with excess production capacity. Clients such as cement plants can switch off non-essential production equipment in Eskom’s peak demand periods for a financial incentive. To maximise the benefits for both the clients and Eskom, accurate electricity forecasting is needed, as are systems enabling a quick response to load reduction requests. In this study DMP opportunities on typical cement plants were identified. A DMP strategy to assist cement plants was developed to achieve maximum cost savings without influencing production, quality and safety. An existing energy management system (EnMS) was adapted to incorporate the new DMP participation strategy. The new EnMS and DMP strategy were implemented at a South African cement plant, resulting in savings of R220 000 per month. This translates into an annual cost-saving potential of R2-million for the plant, and an R13- million cost-saving potential for the total South African cement industry. / MIng (Mechanical Engineering), North-West University, Potchefstroom Campus, 2014

A rapid growth in the national electricity demand is placing an ever-increasing demand on the national electricity supply utility, Eskom. Projections show that the load demand in South Africa may exceed the installed capacity by as early as 2007. This is mainly due to the increase in demand in the residential sector as a result of the electrification of rural and previously disadvantaged communities. However, the industrial and commercial sectors also have a role in this increase. In an attempt to reduce the demand for electricity Eskom has adopted its Demand Side Management (DSM) initiative. This initiative is aimed at lowering the electricity demand in peak times through energy efficiency (EE) or load shift, out of peak demand times. Eskom is implementing the DSM strategy by financing Energy Service Companies (ESCOs) to reduce the demand load of major electricity end-users during peak times. Buildings consume a large percentage of the total energy supply in the world. Most of the energy consumed in buildings is used by the heating, ventilation and air-conditioning (HVAC) systems, as well as lighting. However, a large potential for energy savings exists in buildings. Studies have shown that up to 70% of the electricity consumption of a building can be saved through retrofit studies. However, to capitalise on these opportunities, the ESCOs require tools and procedures that would enable them to accomplish energy savings studies quickly and efficiently. It should be a holistic approach to the typical ESCO building audit. A study of current available software programs showed the lack of holistic tools aimed specifically at retrofit audits, and therefore also the need for such a program. The building simulation program most suited to the retrofit study was chosen and it was used in a retrofit audit. By emulating a retrofit audit with this software, its performance in the field, both positive and negative, could be established. With the experience gained from the retrofit study, as well as input from ESCOs in the industry, a need for such a retrofit tool was established. The simulation program that was tested in the retrofit study is the tool Quickcontrol, as well as the newer version of the program, entitled QEC. The case study showed that even though these packages are well suited to ESCO work, they have certain drawbacks in view of the holistic project approach. The ESCOs require a simple, fast, and integrated procedure for energy audits. This procedure should be embodied in a software program. This study proposes a new integrated procedure for energy audits and the analyses of buildings, in the form of a software tool. This new tool is geared towards the ESCO building audit, in both South A6ica and internationally. It is designed to enable a diplomate engineer to accomplish a building energy and retrofit analysis in two weeks, leading the user through all the main project steps, from data acquisition to writing of the final project report. This is a significant improvement, since it normally takes 50 man-days for an experienced and trained engineering team to complete a full building audit. This tool was used in a case study to test its validity and accuracy. It was found that certain situations would arise in which the criteria that were set for the program would not be adequate. The results from the case study were favourable and satisfied the criteria that were set for the procedure. / Thesis (Ph.D. (Mechanical Engineering))--North-West University, Potchefstroom Campus, 2004.

abstract: A major problem faced by electric utilities is the need to meet electric loads during certain times of peak demand. One of the widely adopted and promising programs is demand response (DR) where building owners are encouraged, by way of financial incentives, to reduce their electric loads during a few hours of the day when the electric utility is likely to encounter peak loads. In this thesis, we investigate the effect of various DR measures and their resulting indoor occupant comfort implications, on two prototype commercial buildings in the hot and dry climate of Phoenix, AZ. The focus of this study is commercial buildings during peak hours and peak days. Two types of office buildings are modeled using a detailed building energy simulation program (EnergyPlus V6.0.0): medium size office building (53,600 sq. ft.) and large size office building (498,600 sq. ft.). The two prototype buildings selected are those advocated by the Department of Energy and adopted by ASHRAE in the framework of ongoing work on ASHRAE standard 90.1 which reflect 80% of the commercial buildings in the US. After due diligence, the peak time window is selected to be 12:00-18:00 PM (6 hour window). The days when utility companies require demand reduction mostly fall during hot summer days. Therefore, two days, the summer high-peak (15th July) and the mid-peak (29th June) days are selected to perform our investigations. The impact of building thermal mass as well as several other measures such as reducing lighting levels, increasing thermostat set points, adjusting supply air temperature, resetting chilled water temperature are studied using the EnergyPlus building energy simulation program. Subsequently the simulation results are summarized in tabular form so as to provide practical guidance and recommendations of which DR measures are appropriate for different levels of DR reductions and the associated percentage values of people dissatisfied (PPD). This type of tabular recommendations is of direct usefulness to the building owners and operators contemplating DR response. The methodology can be extended to other building types and climates as needed. / Dissertation/Thesis / M.S. Architecture 2012

Este trabalho apresenta o desenvolvimento de uma técnica construtiva inédita para dutos enterrados intitulada Geovala. Esta técnica consiste na instalação de um geossintético sobre uma vala, preenchida ou não com material fofo, localizado acima do duto com o principal objetivo de reduzir os esforços que atingem a estrutura. Para contribuir na avaliação do sistema proposto foi realizado um programa de ensaios em pequenas e grandes dimensões no laboratório de geossintéticos da Escola de Engenharia de São Carlos EESC/USP. Neste programa de ensaios foi possível verificar que o sistema Geovala pode reduzir drasticamente as tensões na parede do duto e na envoltória de solo ao redor do duto. Além disso, um método analítico foi proposto para prever os deslocamentos verticais, deformações e esforços de tração gerados no geotêxtil, durante o rocesso construtivo e sobrecarga. Finalmente, verificou-se que os deslocamentos do geotêxtil previstos pelo método foram similares aos deslocamentos registrados nos ensaios experimentais. / This thesis presents the development of an unpublished constructive technique for buried pipes entitled Geovala. This technique comprises of the installation of a geosynthetic over a trench, filled or not with soft material, located above the pipe with the main objective of reducing the loads on the structure. To evaluate the proposed technique small and large scale testing programs were carried out at the laboratory of geosynthetics of the School of Engineering at Sao Carlos EESC/USP. In this testing program it was possible to verify that the Geovala system can reduce drastically the loads on the walls of the pipe and in the surrounding soil. Besides, an analytical method was proposed to predict the vertical displacement, deformations and tensile stress on the geosynthetic, during the constructive process and surcharge. Finally, it was verified that the displacements of the geotextile predicted by the analytical method were similar to the displacements recorded in the experimental tests.

This thesis investigates fatigue crack growth rate behavior in the threshold and near-threshold regimes for a Ti-6Al-4V (STOA) alloy using two proposed ASTM procedures- (1) load-shedding (LS) using a larger load-shed rate than the current ASTM Standard E647 load-reduction (LR) test procedure, and (2) compression pre-cracking constant-amplitude (CPCA) or load-increasing (CPLI) and load-shedding (CPLS). Tests were conducted at a low stress ratio (R = 0.1) on compact C(T) specimens of two different widths (W = 51 and 76 mm) and threshold fatigue crack growth rates were generated. These test data were compared to previous test data produced from the same batch of material using the current LR and the CPCA test procedure. While no test procedure provided an exact representation of the threshold value (?Kth), the compression pre-cracking (CP) procedures were the most promising. The LR, LS, and CPLS test procedures were influenced by prior loading-history and various crack-closure mechanisms, leading to higher ?Kth values and slower crack growths in the threshold regime. The LS tests (at shed-rates of -0.08,-0.32, and -0.95 mm-1) generated ?Kth values that were 15% to 32% higher than the estimated threshold stress-intensity factor range (?*Kth)R=0.1. The CP test procedures are a more accurate alternative for developing near-threshold and threshold fatigue crack growth rates. The CPLS test procedure produced a ?Kth value that was 10% higher than (?*Kth)R=0.1. LR and LS tests produced different ?Kth values as a function of the specimen width for the given load ratio. The CP test procedures produced consistent crack growth rates over the same range of ?K values examined, independent of the specimen width. Further research is required for developing test procedure(s) capable of providing a more definitive representation of the ?Kth value and closureree fatigue crack growth rates in the threshold regime.