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Energy consumption, CO2 emissions and costs related to baths water consumption depending on the temperature and the use of flow reducing valves

Matos, C., Bentes, I., Pereira, S., Faria, D., Briga-Sá, A.
The Science of the total environment 2019 v.646 pp. 280-289
carbon dioxide, cost analysis, electricity, energy, greenhouse gas emissions, monitoring, temperature, water conservation
In the domestic segment, various appliances and processes consume great amount of water and, consequently, energy. In this context, the main aim of this study is to analyse the impact of water temperature, flow and bath duration in water and energy consumptions. The impact on CO2 emissions and a simple costs analysis were also carried out. It included a monitoring plan of 197 baths taken under different scenarios of water temperature and flow. It was concluded that increasing water consumption leads to an increase on energy consumption and that both resources consumptions increase with bath duration. Bath temperature had influence not only on energy consumption, as expected, but also in water consumption, what may be explained by the user's satisfaction during baths with higher temperatures. The use of a flow reducing valve is not a guarantee of water saving which can also be related to the user's satisfaction patterns, given that the introduction of a flow reducing valve can lead to a bath duration increase. In what concerns to the CO2 emissions, it was concluded, as expected, that higher values are obtained for baths with higher temperatures given their relation with higher energy consumptions patterns. A simple costs analysis revealed that having flow reducing valves, with a bath temperature of 75 °C, increased the costs with electricity and water in 119% and 32%, respectively, when compared with a temperature of 60 °C.