Using chocolate ganache for piping a cake?

I'm planning on making a chocolate cake. For piping, I want to use ganache. I know that you must let it cool in the fridge so it can thicken and whatnot, but I'm afraid that after I pipe it, it might start melting gradually off the cake. In my home, it doesn't get too hot, but I'm paranoid about the ganache melting anyway.

Once it's cooled and piped, will it hold its shape? Do I have to store the finished cake in the fridge in fear of it melting afterward?