"The wall is new."
This is Hamza as well and it is written like that to alert the reader that this is to be read as "i" and not as "a". So the word is (Há-iT).
According to my information Alif is only then a Hamza, if it has a sign, meaning a fatha or a damma or a kasra or another sign which is not the case here. It is just an Alif and prolongs the sound of Ha.