I went for radio after iterations of toggle, radio, or not even needing to turn the timer on/off. In the end, since toggle in the current Lutron Design System is defined as "turning on/off." However, at this level, seeing the timer on is not a simple turning on/off but setting it up or not. Hence I decided to differentiate the UI element to reduce confusion and inform the future design system.

Before the final version, I thought of a beginning description explaining the timer. However, during user testing, users can immediately understand the timer. While fulfilling the task of setting a 30-min timer to the device, no user read the text. They said the instruction under timer on is informative enough.

The toggle allows users to control the timer without messing up with the setting. Some lightings serve both as ambient and functional lighting. For instance, the nightstand lamp can be for lighting the room for the whole evening or just for bedtime reading. With the toggle, users can quickly switch mode without re-setting the timer repeatedly.

Suddenly turning the light off can disrupt users' ongoing activity and cause an awful lighting experience. Furthermore, users forget about the settings they have on the lighting. And this can cause them confusion. Another supporting evidence for the design is that users usually have their phones with them, according to the interview. With the notification showing on their phone, users can be informed or can know the reason for the light turning off.

While controlling lighting, users don't want to think. Having a "add ___ mins" will trigger users to consider whether this additional time will be enough for them to finish the task. Whereas having "repeat" gives users the idea of let's do it again.

Having notification can prevent the lighting from interrupting users' spatial experience. However, too many notifications can cause exhaustion to users' digital experience. Users might not want to be flooded with them. Allowing users to turn on and off the notification gives users the authority to reach the balance.

The timer is effective through both digital and physical control (remote control and wall box). If users set a 10-min timer to the hallway light, the system will turn the light off in 10 mins, whether they turned it on via app, wall box, or remote control. The reason is that we know users control their lighting mainly through those big physical buttons.

When the timer turns off the light, we decided to have a slow fade instead of directly turning it off. Cause users are not keeping track of the timer, a sudden abrupt turned off can be frightening. The fade can signal to users that the time is up and that the light is turned off because of the timer.