Assessment of water consumptions in small mediterranean islands’ primary schools by means of a long-term online monitoring
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A key challenge of our society is improving schools through the sustainable use of resources especially in countries at risk of desertification. The estimation of water consumption is the starting point for the correct dimensioning of water recovery systems. To date, unlike the energy sector, there is a lack of scientific information regarding water consumption in school buildings. Available data refer roughly to indirect estimates by means of utility bills and therefore no information on the role of water leakage in the internal network of the school is provided. In this context, the aim of the work was to define and implement an on-line monitoring system for the assessment of water consumptions in a small Mediterranean island primary school to achieve the following sub-goals: (1) definition of water consumption profile considering teaching activities and secretarial work; (2) direct assessment of water consumptions and leakages and, (3) quantification of the behaviour parameters. The installed monitoring system consisted of 33 water metres (3.24 persons per water metre) equipped with sensors set on 1-L impulse signal and connected to a data logging system. Results showed consumptions in the range 13.6–14.2 L/student/day and leakage equal to 54.8 % of the total water consumptions. Considering the behavioural parameters, the consumptions related to toilet flushing, personal, and building cleaning were, respectively, 54, 43 and 3 % of the total water ones. Finally, the obtained results could be used for dimensioning the most suitable water recovery strategies at school level such as grey water or rainwater recovery systems.
KeywordsOnline monitoring system Primary school Sustainable use of resources User behaviour Water consumption Water leakage
The majority of the Mediterranean islands encounter water scarcity challenges due to their small catchment areas as well as the impacts of emerging climate vulnerability and change. Malta and Cyprus have been acknowledged as the water poorest countries in Europe (European Commission 2008, 2012), while a large number of Italian and Greek islands depend on desalination and even on water transfers by tankers (Viola et al. 2014).
Often, water supply companies and Authorities undertake activities to promote efficient use of water. Considering the civil building sector, conservation measures (or water saving measures) generally encourage residents to instal and use high efficiency plumbing fixtures and educate them about water saving habits. Furthermore, interventions aimed at the reuse of water (rainwater and grey water) are strongly recommended and incentivized (Wung et al. 2006). In this regard, the knowledge of water consumptions (per family or per person) is a key issue, useful to planners to build the water reuse systems.
To date, detailed information at the scale of individual building or residential buildings are available. While, at scale of public non-residential buildings (i.e., schools) data are inadequate and generally outdate. An example is represented by primary schools, where the few available data of water consumptions are also characterised by great discrepancies (Almeida et al. 2014; Farina et al. 2011, 2013).
Current literature shows that water consumptions in primary school are generated by the combination of the following factors: (1) behaviours of the staff and student; (2) which and how the didactic activity develops; (3) the services and utilities present in the school (refectory, gardens, swimming pool, etc.) and, finally; (4) the level of the hydraulic infrastructures both in terms of water saving and presence of harvesting and reuse schemes (Almeida et al. 2014; Cheng and Hong 2004; Farina et al. 2011, 2013). In addition, water consumptions were estimated indirectly using input data listed in bills.
Consequently, taking into account the activities that take place in a primary school, an accurate assessment of water consumptions has never been carried out. To the best of our knowledge, no information on the role of water leakage is provided.
In this context, we think that a more clear and detailed knowledge of the amount and type of water consumption in primary schools is fundamental to give right data useful to implement water saving strategies for both renovation and construction of new school buildings.
The definition of the profile of water consumptions during the year considering the teaching activities and secretarial work;
The “direct” estimation of water consumptions and, consequently, leakages;
The determination of the behaviour parameters useful for sizing the most suitable water management strategies (i.e., rainwater system, grey water one, etc.).
To the best of our knowledge, the estimation of consumptions by means of data directly acquired considering a long period (1 year) as well as the possibility to link this estimation to the activities that take place in the school is the main elements of novelty. In fact, to date, consumption data are acquired solely through water bills and as such does not take into account the water leakage contribution. To achieve these goals, the case study of a primary school located in a small Italian Mediterranean island was addressed, as herein described.
Materials and methods
In the school, there are 40 male students, 46 female students, 16 teachers, and 5 auxiliary personnel units so that the rate student/occupant is about 80 %. Students are provided with separate bathrooms while teachers and auxiliary personnel have sheared bathrooms. All the bathrooms are equipped with toilet (WC) provided with single push both for faeces and urine flushing (the volume discharged is 7 L at time) and sinks provided with faucet with maximum flow rate of 12 L/min. The teaching activity is developed in five morning hours, 5 days a week. Gym activities are comprised into the 5 h in the morning and no shower for students is provided. Internal building rooms sweep is operated once a week whilst bathrooms are cleaned every day. In the school a refectory is not present and during the monitoring period no irrigation of the green area was operated.
Online monitoring system
Consumption measurement and real-time communication;
Consumption measurement without communication.
Still, due to poor condition of the school, some corrective measures were performed before starting the measurement of consumption. As described in the “Results and discussion”, these measures have included the replacement of all damaged devices such as trays for toilet or taps for sinks. Furthermore, to quantify the rate of water leakage, the ratio between the monthly water leakage (WL) and the monthly total water consumption (TWC) was defined and computed.
Results and discussion
The profile of water consumption shows a trend roughly constant with an inflexion corresponding to summer break months (see Fig. 4f). Furthermore, the profile of Fig. 4f does not take into account the month of February (Fig. 4e) that we considered as outlier.
The above findings show how it was possible to rebuild the profile of water consumption due exclusively to educational and staff activities overcoming, in this sense, the limitation highlighted in Almeida et al. (2014). Thus, the adoption of water bill-based data did not allow a reliable reconstruction of water consumption profile.
Referring to students (see Fig. 5a, c), the median of water consumptions “purified” by losses (see mark C) was as follows: 7.9 and 7.2 L/day/student considering all the experimentation data and all data with the exception of the outlier, respectively. Furthermore, differently from Almeida et al. (2014) and Farina et al. (2011), the interquartile range was very small highlighting how 50 % of the observations were concentrated around the medians. Also referring to students (see Fig. 5a, c), the median of water consumptions “inclusive” of losses (see mark D) was as follows: 14.2 and 13.6 L/day/student considering all the experimentation data and all data with the exception of the outlier, respectively. Compared with the previous case, it was observed how the interquartile range was roughly constant while the upper whisker is varied.
Furthermore, the trend was roughly the same considering an analysis per occupant (see Fig. 5b, d). As above reported show how the adoption of our monitoring system allow for reliable water consumption estimation. In addition, our results were lower if compared with those obtained from the analysis of water bills (Almeida et al. 2014; Farina et al. 2011).
Water leakage contribution
The adoption of data coming from water bills does not allow a reliable reconstruction of water consumption profile. Consequently, water leakages occurring in the internal network of the school can not be quantified. Thus, it is necessary to adopt a monitoring system as that put in place in our investigation.
The observation of Fig. 6a has allowed the identification of four main phases in line with the assumptions of our experimentation (see “Experimentation framework”). The first phase, indicated with “identification phase”, refers to the identification of initial water leakage (the current scenario of the school). The WL/TWC index corresponding to the first month of measurement, equals to about 67 %, was higher than in the other months.
The second phase, indicated with “correction actions phase”, provides for the implementation of specific corrective measures. Interventions on damaged toilets (the online monitoring system allowed to determine which toilet was damaged) were carried out in March, after the first measurement. It is noted that the WL/TWC index was reduced from 67 % in February to 50 % in March.
The third phase, indicated as “outputs communication phase”, was focused on water consumption communication to the school staff and students. In fact, monitor consumption by knowing values is the principle to which we have been inspired. Still, this principle is in line with advances in recent years in the field of home automation (Sauer and Rüttinger 2007; Zhou et al. 2014).
In this sense, Fig. 6a shows how the WL/TWC index corresponding to April and May was significantly lower than other months with values of 6 and 14 %, respectively.
The fourth phase, referred as “no outputs communication”, was focused on water consumption monitoring without communication of data to the school staff and students. This phase involved the remaining mouths of the experimentation as shown in Fig. 6a. The objective of this phase was to highlight the contribution of water leakage in a situation where the staff (and above all the students) do not know the instantaneous measurement of consumption (and as such water leakage). In addition, this scenario is the most common one in a school. Figure 6a shows how the WL/TWC index tends to rise with the exception of the month of September. Roughly, the average value was equal to about 50 %. The above findings show that the instant knowledge of measures generates a sort of “preventive action” reducing consumption and simultaneously water leakages (Sauer and Rüttinger 2007). Finally, Fig. 6b shows the relationship between water leakages and the total water consumption during our experimentation. Broadly, water leakage was approximately 54.8 % of the total water consumption.
Type of person
Type of water
Toilet usage data highlight how the staff, due to a longer presence at school, had a higher frequency respect to students (see Table 1).
Female and male students have shown a quite different behaviour so that, despite they were present with similar number, the female were responsible for almost double of the consumption (see Table 1). Even though the Italian socio-economic context is different, our results confirm the existing proportions among male and female students as reported in Cheng and Hong (2004) with reference to the Taiwan situation.
A further considerable result is the comparable quantity of water used for both cleaning and flushing purposes equal to 8.38 and 10.36 (L/day/person), respectively. The water consumption for the internal building rooms sweep appears very low. This result was due to a very high building surface in relation to the number of occupants (23 m2/occupant). In fact, some rooms are neither used nor have a very low frequency use so that the sweep was reduced.
The online monitoring system allowed evaluating water consumption due to educational and staffing activities of a small Mediterranean island primary school. The monitoring involved the installation of 33 water metres, annual-basis experimentation with the possibility to communicate the instantaneous values of consumption to the school staff.
Water consumptions were in the range 7.2–7 L/student/day and 13.6–14.2 L/student/day in the case of network without water leakage and network with water leakage (the most common situation), respectively;
Water leakage was 54.8 % of the total water consumption. Values of 10 % were obtained in cases where consumption has been communicated instantaneously to the school staff highlighting the importance to know consumption in real time;
Considering the behavioural parameters, water consumption related to toilet flushing, personal cleaning and building cleaning were 54, 43 and 3 % of the total water consumption, respectively. Considering only toilet flushing, frequencies (in terms of time/day/person) were 0.94, 1.43 and 2.63 for male student, female student and staff, respectively. On average, the corresponding water demand was 10.36 L/day/occupant considering both students and staff. Instead, cleaning water demand was 8.38 L/day/occupant comparable to this way, to the toilet flushing water and, finally;
Obtained data could be used to implement at school level water recovery strategies such as grey water or rainwater recovery systems.
This work was carried out within the Egadi Project (http://progettoegadi.enea.it/it) as a part of the Sicily Eco-innovation project funded by the Italian Ministry of Education, University and Research (MIUR) in accordance with the provisions of article 2, paragraph 44 of Law 21 December 2009 (Finance Act 2012). The authors would like to thank the staff of the A. Rallo primary school, the municipality of Favignana and Mr. Giovanni Massano for his technical support during the monitoring system implementation.
Compliance with ethical standards
Conflict of interest
There are no conflicts of interest.
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