Browsing by Author "Nel, P. J. C."

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    A computationally inexpensive energy model for horizontal electric water heaters with scheduling
    (2016-03) Nel, P. J. C.; Booysen, M. J.; Van der Merwe, A. B.
    ENGLISH ABSTRACT: Electric water heaters (EWHs) remain one of the main contributors to energy consumption in countries where they are used. EWH models serve as a step towards achieving optimised control, and can also be used to inform users of expected savings due to changes, if the model is energy-based. Various models have been proposed, but none of them include more than half of the six key features that the model presented in this paper supports: horizontal orientation; schedule control; low computational complexity; validation of the model; multinodal stratification; and multinodal standing losses. The presented model is validated against six datasets: four comprising 900 hours with multiple water usage events; and two with only standing losses. The results show that the model estimates energy consumption over ten days including usage with an error of less than 2% and 5% for schedule control and thermostat control respectively. The simulation model is simple enough to execute ten days of simulation in less than 100 milliseconds on a standard desktop machine, 150 times faster than a prominent model from literature, making it also suitable for large scale simulations or for use on mobile devices.
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    Energy perceptions in South Africa: An analysis of behaviour and understanding of electric water heaters
    (Elsevier, 2016-03) Nel, P. J. C.; Booysen, Marthinus J.; Van der Merwe, B.
    Using data from an online national survey conducted in South Africa, this paper aims to investigate: the awareness of energy savings measures for electric water heaters (EWHs); whether or not consumers are implementing suggested measures; and if consumers understand and effectively control their EWHs’ energy usage. Additionally, the data is used to determine the success of educational and rebate programmes aimed at reducing residential energy usage and to determine possible motivations for encouraging users to reduce or alter their EWH energy and warm water consumption. The results of this questionnaire indicate that: convenience is a key factor in consumers’ willingness to implement curtailment actions; users don’t understand the energy consumption of their EWHs; and they don’t know how to control their EWHs efficiently.
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    ICT-enabled solutions for smart management of water supply in Africa
    (2014-12) Nel, P. J. C.; Booysen, Marthinus J.; Van der Merwe, B.
    ENGLISH ABSTRACT: Pervasive and ubiquitous technologies that include mobile device applications, machine to machine communications, and cloud computing, are increasingly used for cost-effective data aggregation and information dissemination. Recently, this trend has started to gain momentum in the water sector and is being used for various management and monitoring tasks, such as remote leakage detection, automated meter reading and enhanced usage feedback to water users. This paper analyses the challenges faced by various stakeholders (consumers, utilities, etc.) in the water supply industry. Application of the said technologies is then proposed to address these unique challenges and the varying data needs of all stakeholders. An example solution, with a mobile device application and supporting cloud computing solution, is developed and presented as a proof-of-concept to further illustrate the potential use of ICT for water supply management.
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    Saving on household electric water heating : what works best and by how much
    (IEEE, 2017-12) Nel, P. J. C.; Booysen, Marthinus J.; Van der Merwe, B.
    Electric heating of water for domestic use is a substantial component of total household energy costs. Thermal energy in a water heater is either used (as warm water) or lost to the environment. Various approaches to reduce the losses and improve the efficiency of these notoriously inefficient and costly water heaters have been proposed and are employed. However, given the complex factors at play, making sense of the savings approaches and choosing the right one for the right use case is not a simple task and often misunderstood. This paper addresses this problem by comparing some of the commonly employed approaches, including schedule control, change in set temperature, use of thermal insulation, and reduction in consumed volume. We also compare the impact of environmental factors, such as changing the ambient temperature around the water heater and the cold inlet temperature. The results show that for the consumption profiles and use cases evaluated, schedule control is the most effective, followed by insulation of the tank and piping. Combined, these two interventions save up to 25%. We also find that the effect of the temperature of the cold inlet water dwarfs that of the ambient temperature, is in line with other approaches, and means the installation status quo needs to be reconsidered.
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    Saving on household electric water heating : what works best and by how much?
    (Institute of Electrical and Electronics Engineers, 2017) Nel, P. J. C.; Booysen, M. J.; Van der Merwe, B.
    Electric heating of water for domestic use is a substantial component of total household energy costs. Thermal energy in a water heater is either used (as warm water) or lost to the environment. Various approaches to reduce the losses and improve the efficiency of these notoriously inefficient and costly water heaters have been proposed and are employed. However, given the complex factors at play, making sense of the savings approaches and choosing the right one for the right use case is not a simple task and often misunderstood. This paper addresses this problem by comparing some of the commonly employed approaches, including schedule control, change in set temperature, use of thermal insulation, and reduction in consumed volume. We also compare the impact of environmental factors, such as changing the ambient temperature around the water heater and the cold inlet temperature. The results show that for the consumption profiles and use cases evaluated, schedule control is the most effective, followed by insulation of the tank and piping. Combined, these two interventions save up to 25%. We also find that the effect of the temperature of the cold inlet water dwarfs that of the ambient temperature, is in line with other approaches, and means the installation status quo needs to be reconsidered.