Re: Improving perceived loudness when system is constrained
Daniel, hopefully your consultant already considered this but have you looked at ASHRAE or any other sources that may provide some reference acceptable ambient noise levels for that type of space? I understand the tenant may be upset that they hear anything but unless their lease or sales agreement supports that they should expect to not hear anything then it may legally be a moot point. It may not make the tenant happy to hear that but if they understand that all of this effort is being expended just to try to make them happy and not because it has to be that may help.
If it is 'everywhere' I'd be looking at the plans for vertical chases, ductwork, etc. that the two spaces may share. And if the same issue does not apply to an even greater degre on intervening floors I'd be looking very carfeully for what may make that particular condition different from the others.
I once ran into a situation where a renovated building ended up with classrooms over a club. They went to great lengths to address direct vertical sound isolation over the main club area and seemed to have done a good job there, however they still encountered noise virtually everywhere in the spaces above. Didn't take long to find that in back of house areas just outside the main club floor were a number of penetrations of the slab left from original piping that had been removed, for example the bathrooms downstairs had originally had matched bathrooms directly above with numerous vertical plumbing and electrical connections that had all been removed during the renovation. Because they built walls upstairs right over the penetrations they never filled the resulting holes in the slab, thus allowing noise to get into the walls on the upper floor and from there also into the ceiling space. The real point of bringing this up is that sometimes small flanking paths that are not immediately evident can manifest as something more general while significantly limiting the overall isolation
