I'm trying to destroy a building geometry and it has been pre-fractured. Because of this there are particles leaking everywhere! because only part of the geo is being destroyed i thought it would be better to create a VOP to only emit particles through velocity.

When i create a POP VOP and to perform a simple test i just hooked up life to velocity but it seems to give the opposite effect so the life node is creating velocity. Is there a way to invert this effect? i've tried searching around for a similar effect but can't seem to find any.

You can use debris shelf tool which does decent job.

Without Life Variance life will be same and constant for all the particles. So it doesn't make any sense to use life for velocity since life is constant float. It's just like having constant vop plugged to velocity inside.

Not sure what you mean by invert (direction or magnitude).

There is negate vop, compliment vop and fitrange vop to do the job.
You can also divide constant vop (value 1) by life or any parameter you want.

If things doesn't work for you, better to post file so that somebody can have a look into.