User preferences and water use savings owing to washbasin taps retrofit: a case study of the DECivil building of the University of Aveiro

During the last decades, achieving water efficiency in buildings has increasingly become an important challenge in the scope of sustainability. Water consumption is directly related to individual conduct. Despite the various technological improvements in fixtures and appliances, their performance will be influenced by human preferences and behavior. As a result, the potential for effective water consumption saving is influenced by behavior change as well as water-efficient fixtures and appliances. This work evaluates the impact of user preferences and behavior change on the water-efficient performance of tap aerators in a case study building: the Department of Civil Engineering building of the University of Aveiro, Portugal. Four aerators with different discharge reductions and types were installed in the toilet’s washbasins and the user’s preferences and behavior change measured through direct and online questionnaires. It was observed that the effective water consumption reduction (15 to 49%) was less than the discharge reduction (30 to 70%), confirming that user factors influence water savings. Water use reductions in the tested range (2.0 to 6.7 l/min) also varied according to gender, with male users using less water than their female counterparts. It was noted that an awareness of sustainability values prevailed amongst the users when confronted with the choice between comfort and water efficiency, although differences were observed in the user preferences regarding the various aerators. When confronted with the information that the lower discharge aerator would contribute to a reduction of about 70% on the water discharge, 25% of the users agreed with its use, even if it resulted in a certain degree of dissatisfaction. In comparison, only 8% of the users completely disagreed with its installation. On average, the water consumption reduction was 46% smaller than the discharge reduction achievable with the aerator alone. This further confirms the user factors inform the degree of water savings that is achievable from water-efficient fittings and fixtures.