Gabe wrote:What is Brewhouse efficiency? I've seen this term used but don't know what is meant by it. I have always done extract brewing but will be starting to do all grain in a few weeks when I finish building my brewery.
If, during your mash, you were able to convert all the starches and extract all the sugars into your wort, you would have 100% efficiency. This, of course, won't happen. Brewhouse efficiency is simply a way of comparing the specific gravity of your wort with the specific gravity you would have gotten had your efficiency been 100%
For example, if the maximum possible OG for the wort from your recipe was 1.060 and you achieved 1.045, your efficiency would be 75% (45/60=.75). This is the greatly simplified version. For a much better explaination, please check out http://www.howtobrew.com/
It is necessary to figure your efficiency for a number of reasons. First, if your efficiency really sucks (say less than 60-65%) you need to examine your mashing process. Most folks get in the 70-75% range, some into the mid 80% range.
The second reason is that when you use another persons recipe, you need to compare your normal efficiency to the efficiency used in the recipe in order to modify the amount of base grains used so you can come up with the same gravity. Likewise, if you are designing your own recipe, this figure is necessary to figure grain amounts.
The third reason is not so important for homebrew use. Simply with higher efficiencies, you need less grain to get the same OG. On a commercial scale, this adds up to big $$$.
There are 2 separate points at which you can determine efficiency. The first is at the preboil point. This tells you just how efficient your mash was. The second point is after the boil. This tells you your overall system efficiency. These will differ as the second takes into account the amount of wort left in the kettle, mixed with the hot/cold break and absorbed by the hops.
To get an accurate efficiency, you need both an accurate gravity reading (remembering to adjust for temperature) and an accurate volume measurement. I use a measuring stick for my brew kettle and have marked the volume in half gallon increments with paint markers on the outside of my carboys.
Hope this helps more than confused you.
A wise old philosopher once said, "You can't always get what you want, but you can always get what you need."