When developing your content for MEP in particular, the choice to
make content hosted or not can have some long term consequences. Consider
if your company will work in an environment with all content in one model, or
if the architectural model will be linked in to your MEP model. If you're
working all in one model, then the wall hosted, and ceiling hosted objects may
have some advantages. If you're working with an architectural link, then
you will likely want to consider unhosted families with the occasional surface
hosted.
For one, with a link, there are no walls
or ceilings, but all surfaces. If you are working all in one model, then
the ceiling hosted objects will cut the ceiling leaving voids for the ceiling
grid. Another thing to always remember with MEP objects that are hosted in any
way, if the object they are hosted to gets deleted, they become orphaned. At
best they stay where they were, and occasionally they get lost out in left
field. More recent releases are better about not changing the positions
of objects, but they can still get left behind.
Let's say the ceilings that lights are
hosted to get deleted, and a new one created one foot higher, the lights will
now be too low, the lighting calculations will be wrong, and the plenum space
coordination is now shot.
So now let's consider the unhosted option
workflow. During the design development phase, often the ceilings are not
developed enough to safely host devices to, without knowing you will need to
re-host them again later. There are many workaround to this for hosted content,
all with some undesired side effects. If your content is unhosted, it
still needs a level reference, and you can set a height offset. Later you
can use excel to synchronize the space heights, and your light height offset
values and get most of your lights in the right place at one time.
