## Day 462

First day of exams. Fever. Cough. I felt not quite bad enough to stay in bed but reasonably wretched for the *Brewhouse Calculations* exam, which started–of course–at 8:30 a.m.

Writing an exam is never a pleasant experience, and today especially so. Strangely enough, despite how I felt, I got through the calculations part of the exam with no problem. Grain weights, krausening, raising mash temperature via infusion, they all fell before my pencil and calculator. One would think that aceing the calculations in *Brewing Calculations* would guarantee me a good mark, but there were also several non-calculation type questions that my fuzzy mind had to contend with, and the old memory banks were clearly having a hard time. (“Name eight factors a brewer has to keep in mind when making a high-gravity brew” was worth an astounding 16% of the final mark).

Oh well, on to *History of Beer*. The final exam for this was a bit more straightforward until I got to the last page. The final three questions asked my opinion about the course, what I found useful, and any changes I would suggest. Yes, I got marks for course feedback. Hmmm.

Another final exam tomorrow, so off to bed for some restorative sleep.

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**Tags:** Brewhouse Calculations, final exam, History of Beer, Niagara College

December 11, 2012 at 9:05 pm

Is this the type of thing where you learn the calculations for the class/test and then in real life you would always use a brewing program? Can never get away from that I see, but probably a good idea to know the basis at least at one point in your life.

December 11, 2012 at 9:47 pm

I think it will vary from person to person. Some will go back to on-line calculators, others will sit down with a pencil and a calculator. I kind of split the difference: I set up an Excel spreadsheet with the various formulae for grain weight, colour, hops, etc. It’s faster than using a calculator, but still uses what I learned–and I’m sure about the formulae being used. [If you use an on-line program, you have to trust that the programmer a) knew the proper formulae, and b) didn’t make any mistakes.]

December 11, 2012 at 11:20 pm

And I suppose you will be sure which formula you are using when there are several options like with IBUs and such.

December 12, 2012 at 8:58 am

The formula also tells you the relationship between the various factors–how brewhouse efficiency will affect the specific gravity, etc. It’s also handy that by rearranging an equation, you can solve for one of the other variables. For instance, suppose I want to know what my brewhouse efficiency is, rather than just make guesses. The equation for grain weight is

GW in kilograms = (percentage of grain in grist bill times volume of mash in litres times desired specific gravity times desired OG as percent degrees Plato) divided by (percentage extract of your grain (coarse grind, dry basis) times (1 minus the percentage moisture content of the grain) times brewhouse efficiency); or to put it a bit more succinctly:

GW = (%T x V x SG x P%) / (%E x (1-m%) x BE%).

But I can also check on my brewhouse efficiency by using the same formula, rearranged by math principles learned in primary school:

BE% = (GW x T% x V x SG x P%) / ((1-m%) x E%)

Knowing the relationships between the various factors is what is invaluable about knowing the equations.