How do I keep consistant with the hv30 on different shoots but same lighting area
 

The iris compensation rubbish will change to suit the room. I know I can set up in the same lighting each time, but is there any way of making sure I have the same amount of db etc.

I don't think there's anything you can do to assure that all of the settings will be the same from shoot to shoot. There just aren't any controls that you can directly adjust to assure a consistent setting. You can try the "cell phone trick" to help lock things down, but there's no guarantee that it will do the same thing to the camera every time. Google the term in quotes if you're not familiar with this.

That said, you can be reasonably confidant that if you set up the lighting the same way for each shoot that your results will be visually consistent even if they are not technically identical.