Brewhouse Efficiency - Kettle or Bucket?

I'm a bit cornfuzed here.

If I'm siphoning wort from my BK into my fermenter, which volume do I use to figure brewhouse efficiency? Do I want the volume in the kettle with all the trub, etc., or do I want the final volume in the bucket?

I assume I need the BK volume since that's the equivalent of what I used to use when I just dumped all the contents of the BK into the bucket.

edit: pretty obvious I need BK volume thinking about it now. I've been a bit out of whack since I started siphoning and leaving wort behind in the kettle. I guess I need to plan for a larger batch size.

Actually, I'm guessing either would work so long as proper target volume adjustments/loss estimate calcs are used.

No, brewhouse is based on the volume in the fermenter because it has to factor in losses such as sludge in the kettle, hop absorption, etc. Think of it as literally how much grain it took to get what's in the fermenter. Mash/Lauter efficiency (or efficiency into the boiler for Beersmith fans) will have already accounted for the extraction effiiency. The only thing different between the two numbers is system losses into the fermenter.

Well, that makes sense and it is what I've been doing. But, that being the case, leaving the trub behind is costing me roughly 5% in efficiency vs. chucking it into the fermenter. Of course, I have no idea how much of that is real loss and how much is actual trub bits I wasn't ever using anyway...

Agreed. Brewhouse is usually a couple points lower just as you've found. If the numbers were always the same, we wouldn't call it something different ;-)