Edinburgh Napier University

  One of the major issues facing the world in the 21st century is climate change. However, sustainability has become a crucial concept to combat extreme consumption and utilization of environmental resources leading to climate change. The bathroom has been estimated to be the principal user of environmental resources in households in the consumption of water, electricity and gas. Therefore, the challenge that how a combined water and energy saving unit in the bathroom will contribute to the sustainability of the houses remain unresolved. This study challenges and extends existing knowledge on sustainability related to the smart bathroom systems from social, environmental, and economic standpoints to achieve a highly efficient water and energy consumption in the bathroom. This is with regards to the potential which the renewable-based options, advanced smart control techniques and profitability measures of bathroom reinforces the three pillars of sustainability.

This study reveals that a range of technological challenges are based on the individual components and technologies in the bathroom and concludes that a holistic approach is required for an effective modelling in the bathroom. This allows the examination of energy and water flows in the complex systems, shaped by various social, economic and environmental forces. The method this thesis presented adopts a conceptual modelling approach that is based on holistic modelling to design and implement a bathroom unit that is sustainable and smart. The system components assume three flat plate solar collectors, a solar heat exchanger, a pre-heating storage tank, main hot storage tank with auxiliary boiler system, mixing devices and two circulators to collectively improve the overall system efficiency. Parametric analysis was also conducted to know how change in variable parameters like location, load and switch-on temperatures will affect the performance of the system designed. Furthermore, a smart control for the bathroom system is designed to use the fuzzy logic controller, it was used because of its easy adaptability to the bathroom users’ pattern.

While the result shows that solar total annual energy supplied to the bathroom system is 4,878 kWh and the total annual energy consumed by the system is 8,675 kWh with average annual system performance of 0.95. The solar thermal systems are still able to save between 50% and 60% of the energy that would have been required annually to heat up the hot water using conventional energy sources. After optimizing the system, the bathroom system completely provided an overall annual CO2 savings of 1,398 kg. This study has shown the contribution of renewable energy source and smart control technologies in the bathroom and the significant contribution it makes to the water-energy nexus, levels of energy consumption and carbon emissions. The outcome of the fuzzy logic control design shows that the controller stabilizes and shows transient at the user desired temperature (20°C and 25°C) and flowrate (0.5 l/sec and 0.9 l/sec). The control has little overshoot, steady state error and stabilises quickly to the precise user desired flowrate and temperature hereby enhancing the efficiency of the reference system.

This study has established a strong quantitative and qualitative links between three dimensions of sustainability. This has made a major contribution to the design of sustainable development and infrastructure by developing a sustainable bathroom framework that have been presented in this study.