By Mike Blaesser

When it comes to efficiency, only one number matters

We brewers are an obsessive lot. We worry about everything.
My pH is too high or too low. I fermented too hot or too cold. I dry-hopped too long/too short. I’m sure I’ve ruined my beer.
With so many things to fret about, it’s good to know there is at least thing you don’t have to spend a lot of time dwelling on. 
And would that be?
Sure, efficiency is important. You can’t just ignore it. But you don’t have to go down every rabbit hole chasing elusive numbers just because you think that, well, maybe, you’re not good enough. Other brewers, you read, are 75, 82, even 88% efficient. And you, well, 63% is a good day.
Truth is, you only need to chase one number, and that’s the one you can hit consistently. Efficiency is not a numbers game to see how high you can get. Efficiency is a guidepost to help you along to predictable brewing results. It’s one of the keys to repeatability. A mark of a brewer in control of their system.
Just so we’re on the same page, we’re talking about how much sugar you can extract from your grains, and how much makes it through the brewing process and into the fermentor.
The amount of sugar extracted during the mash is mash efficiency. The amount of sugar that makes it the rest of the way is brewhouse efficiency. How do the two differ?
OK … you want rabbit holes. You’re that kind of brewer.
Rabbit Hole #1 … If you’re familiar with Beersmith brewing software, you know you have a lot of information at your fingertips. So jump down here if you want to learn about brewhouse and mash efficiency.
Let’s continue and at least pretend you don’t want to chase mythical numbers. But really, you want to know, what is a good number. And I’ll repeat, the one you can hit consistently.
The brewing magazine Brew Your Own sets the brewhouse efficiency for their recipes at 65%. Zymurgy, the magazine of the American Homebrewers Association, sets their mash efficiency for recipes at 70%. They don’t list a brewhouse efficiency, but you know it’s going to be below 70%.
Morebeer doesn’t list an expected efficiency for the kits they sell, but you can look at the spec sheets and do the math. I checked out an amber ale kit and a hazy IPA kit, and the efficiency for both kits landed at 65% on the low side and 70% on the high side.
At this point you might agree this efficiency thing really is something you don’t have to fret about, but isn’t it way expensive to be an inefficient brewer? Efficiency saves me money! True enough, and if I were a commercial brewer who had to think about profit as much as good beer, I would jump down every rabbit hole and turn down every tunnel in search of efficiency. When you brew a lot of beer, even small gains in efficiency can mean big savings.
For homebrewers, not so much.
Rabbit Hole #2 … Efficiency and grain bill. Go to your brewing software and create a recipe, say a single-malt pale ale with an original gravity of 1.050. Now, play with the efficiency setting and see how much grain you need to add, or can save, depending on your efficiency.
Didn’t jump down that one? Then let’s play the savings game. As you noticed from the Morebeer examples above, middle-of-the road efficiency doesn’t cost you a penny. Both 65% and 70% were within spec.
Suppose, though, you want to be dead-on accurate. You want 5 gallons of a single-malt beer and you want an original gravity of 1.050. For that, you’re going to need 250 gravity points.
Rabbit Hole #3 … Gravity points explained.
If you just prefer to trust my math, let’s follow the numbers. Using a typical 2-row grain, a 75% brewhouse efficient brewer would need 9.3 pounds of grain to get an original gravity of 1.050. A 70% efficient brewer would need 10 pounds. A 65% efficient brewer would need 10.7 pounds. I’ve been known to hit 58% on occasion, and I would need 12 pounds.
What does that translate to? With 2-row malt going for about $2 a pound, a super-efficient brewer might save $2 on a 5-gallon batch. An inefficient brewer might have to spend an additional $3. I don’t know about you, but that savings, or added cost isn’t enough to make me chase a number.
And yet, I recently bumped up my efficiency. Why?
Every now and then I review my brewing practices. I read notes on past brews, and I go into the session data and look for trends, such as hitting numbers accurately, or coming up short on volume. I realized my efficiency used to be higher, and I also knew I had gotten lazy about heating my sparge water. I had quit worrying about sparge temp and used it as is. And efficiency dropped. I started heating my sparge water again and I got about a 5-point bump in efficiency.
Does it matter? Not really. My beer is no better or no worse. But heating water is a pretty easy step to take. Wasn’t even a small rabbit hole.
A bigger rabbit hole? 
Rabbit Hole #4 … Pick a recipe in your brewing software, go into the session data and play with Starting Gravity settings and the quantity of wort that makes it into your fermentor. What kind of changes are needed to move the needle on brewhouse efficiency?
The session tab from Beersmith brewing software recipe.
When I brew, I don’t worry too much about my final volume. I could work harder at getting more wort into the fermentor, but I am just a little bit lazy and if I leave a couple of beers behind, so be it. This is an area I’m not inclined to spend time or money on just to improve a number. So my brewhouse efficiency suffers. But it’s only a number. My beer is not going to be better or worse if I get every last drop out.
We all have our rabbit holes, and yours might be efficiency. And that’s OK. Your beer, your way. Jump in if you so desire. For me, the gains to be made by constantly chasing numbers for the sake of numbers isn’t worth the effort. Now dialing in consistency? Yep, that’s worth the effort.

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