Why did Federation starships need transporter rooms? [duplicate]

Question

Possible Duplicate:
In Star Trek - What's the Point of the Transporter Room?

If transporters can beam people directly from site-to-site (i.e.: straight from the surface of a planet to the bridge (as seen in STNG S3-E3, "The Survivors", and other episodes), why is a dedicated transporter room and pads required aboard a starship?

Answer 1

I recall something about energy utilization. Most efficient was a pad-to-pad transport, less efficient was non-pad to pad (or vice-versa) and least efficient was non-pad to non-pad. Wish I could tell you where I came across this but can't :( Think it was in a TNG episode but can't swear to it.