Living in a tropical country, rooms that are not air conditioned can get very hot. Considering this, the kitchen is a good place to start using domotics, since it does not have conditioned air. In this room, i want to manage two things : lights and temperature.

Air conditioning is not an option in this room, so i will have to rely on ventilation for two tasks : i am looking forward to use a fan to push hot air outside, and fans oriented toward the user to refresh him/her. For the lights, there is a main light on the ceiling, but i want to add lights in various locations (kitchen sink, etc).

Now, on the automation of this.

-Automation of the lights : the goal here is to turn on the lights according to the user activity. The lights should turn and off in an automated fashion. For the sink lights, the system should detect when a user is in front of the sink, or when hands are over the sink. I will try a PIR sensor to detect the user, and depending on the size of the things that can be detected, to detect hands over the sink.  Lights will be turned off if no user was detected for a fixed amount of time (something like 1 minute, to be determined, may be something that can be specified by the user).

-Temperature control : depending on the room temperature, fans should activate automatically to exhaust hot air. If an user is present, and the temperature is over a user set value, fans will be sending air towards the user. 

The user will have manual control over all those fonctions. However, i want to keep the interface simple, with few buttons, and simple controls. I thus plan to have 3 buttons with a LED each. One red, one blue, and one white. White is for lights, blue for cooling, and red is a general control.

The idea is the following : if the user pushes the white button, it enables lights. if he pushes again, lights are off. If the user holds the white button, automated mode is enabled. If held again, it goes back to manual mode. The button led will signal the state. If the system is off, and in manual mode, it will be slightly lit, or blink discretely, every second or so. The goal is to be able to locate the buttons in the dark. If on, it may be lit fully. At last, if the system is in auto mode, the led will be PWM driven to fade in and out, in a "breathing" pattern.

The same goes for the temperature control switch; and the general switch works in the same way, but controlling the whole system (if you push the red button, it will turn on/turn off all systems).

General disposition of the user interface

General switch	Lights switch	Temperature control

Later on, i may include other "codes" to control specific parameters. However, all simple actions must be used to activate/de-activate the most important functions.

I may also include a small LCD screen to display temperature and date, and maybe other parameters. However, the system will be usable without the LCD.