No, ignoring the silent treatment isn't showing him that it has no consequences. It isn't your job to CREATE consequences for him.
Ignoring the behavior is simply not getting sucked into it. If you must speak to him (e.g., "I'm going out for the day, be back at five.") then do it. If you don't need to speak to him, don't. Why aggravate yourself?
I know it feels like something has to HAPPEN. It doesn't. When and if he chooses to talk, he will talk. Until then, you can just carry on.
It doesn't feel natural, but that's because it's new behavior. Just stick with it. It will become more natural.