ST is a showering system imagined to effectively reduce water waste in the house environment.

It recognizes the specific user in the shower, and depending on his preferences sets the ideal duration of each different phase of the shower: initial wash up, soaping, and rinsing.

The duration of each phase will change dynamically during the shower depending on manual user changes of water flux. In the last phase the system will gradually decrease the flux to a minimum, eventually stopping it completely.

The progression of each phase is characterized by the succession of three different light color (first green, then yellow and finally red) and the transition between phases is notified by a specific sound.

Besides the shower, the system will try to improve the whole bathroom environment using a fan. It will measure the humidity created by the shower or already present in the room and it will turn the fan on upon reaching a certain level.

• ST: acronym for the name of the system: Shower Time.
• Preferences: settings customizable through the web application regarding the overall duration of the shower.
• Phase: one of the three interval of time in which the shower is divided.
• Fan: a devices connected to the system which ventilates the bathroom in order to reduce humidity.
• User interface: a web application through which the user can interact with the system.
• Dynamic Phase Duration (DPD): during the shower the system is continuously computing the expected duration of the current phase given the current parameters measured by the sensors.

• Registered user: someone who lives in the house and is registered in the database of the system.
• Guest user: someone that happens to be in the house and wants to use the shower, and who has not his own customized preferences.

Functional Requirements (FR)

1. User interface

   ID	Description	Priority
   1.1	The user can be identified by the system just before entering the shower (if already registered).	1
   1.2	User registration in the database of the system and setting of preferences through a web-application.	2
   1.3	User interface in the web application provides the various statistics, both general for the house and specific for each different user.	5

2. Preferences

   ID	Description	Priority
   2.1	Setting ideal duration of each phase.	1

3. Monitoring

   ID	Description	Priority
   3.1	User presence detection under the shower.	1
   3.2	Humidity measurement for fan activation.	1

4. Interacting

   ID	Description	Priority
   4.1	Colored lights marking the progression of a phase.	1
   4.2	Sounds marking the transition between phases.	2
   4.3	The system reacts to the user manual changes of flux and temperature computing an updated DPD.	1
   4.4	Button to end the shower and stop the system in case the user finishes before the predetermined time.	1

5. Acting

   ID	Description	Priority
   5.1	Activation of the fan when the humidity threshold is reached.	1
   5.2	Flux reduction when entering the soaping phase.	2
   5.3	Gradual flow decreasing, and eventually stop, during the last phase.	1

6. Suggestions

   ID	Description	Priority
   6.1	The system notices when the user stays in the shower less than programmed and proposes to reduce the shower duration for the next times.	5

Non-Functional Requirements (NFR)

1. Portability

   1. User interface: the user interface is available through every device provided with a browser and an internet connection.

2. Usability

   1. Language: the user interface is available in English.
   2. System working conditions: The user interface works only when the system is on.

3. Efficiency

   1. System response time: the time between the pressing of the button and the starting of the water flow must be less than 5 seconds.
   2. System launch time: When the user enters the bathroom and turns on the system it should be operative in less than 1 minute.