Brewhouse Efficiency Question

[thomer]

I have recently started AG brewing (BIAB). I am a little confused by Brewhouse Efficiency. I totally understand what it means and how to calculate it (I think). But as the OG is a figure we all strive to achieve from a recipe, then the Brewhouse Efficiency will be a fixed number will it not??

You have your grain points - that is a set number (use 74 as an example).
You hit your OG on the dot - so that is a fixed number also (use 1.056 as an example).
So the Brewhouse Efficiency (56/74 = 76%) will never change unless the OG changes, which is different from what the recipe calls for.

I am sure I must be missing something.
Or is this only really relevant when creating recipes from scratch.
ie. you know the grain points and your BHE and its actually giving you the expected OG?

 

[VikeMan]

Conversion Efficiency is the percentage of starches that get converted to sugars and unfermentable dextrins.

Lauter Efficiency is the percentage of those sugars/dextrins that make it into the kettle.

Mash Efficiency is the percentage of total potential carbs that actually make it into the kettle.

Brewhouse Efficiency is the percentahge of total potential carbs that actually make it into the fermenter.

Which one(s) are you interested in? Also, you can't calculate Mash Efficiency or Brewhouse Efficiency without taking the volume of wort into account (as well as the gravity). There's a presentation on Mash Efficiency and Brewhouse Efficiency that you can view or download from the library at this link:
http://sonsofalchemy.org/library/

 

[thomer]

Which one(s) are you interested in? Also, you can't calculate Mash Efficiency or Brewhouse Efficiency without taking the volume of wort into account (as well as the gravity).

It was Brewhouse Efficiency I am initially interested in. But the same issue applies. To get the grain points you take into account the wort volume, which for 95% of recipes will be 5g (ish). So again its a fixed number unless you are changing the recipe.

 

[VikeMan]

It was Brewhouse Efficiency I am initially interested in. But the same issue applies. To get the grain points you take into account the wort volume, which for 95% of recipes will be 5g (ish). So again its a fixed number unless you are changing the recipe.

95% of recipes may target 5 gallons into the fermenter, but in practice, most of the time you'll end up with a little (or a lot) less or a little (or a lot) more. The measured volume, the measured gravity, and the theoretical potential yield from the grain bill are all used to compute brewhouse efficiency.

Also, Brewhouse Efficiency is anything but fixed. For example, recipes with larger grain bills (but same boil time/final volume) will get lower mash and brewhouse efficiency than recipes with smaller grain bills. The math to predict the changes in expected efficiency is not trivial, but there are tools available.

If you mean something else by "fixed number," please explain, perhaps working through a full example.

ETA: and again, I recommend taking a look at the presentation.

 

[VikeMan]

I just re-read your first post. I might (or might not) now understand what you're asking/saying. If a recipe calls for "X" gallons of wort into the fermenter at "Y" OG, with "Z" grain bill, then anyone actually achieving X and Y with the recipe as written will (by definition) have had the same brewhouse efficiency. This is true.

But, when you brew someone else's recipe, one of the things you should do is scale the grain bill up or down, so that it's sized to achieve X and Y with the efficiency that you expect in your brewhouse. There is no "standard" brewhouse efficiency.

 

[thomer]

But, when you brew someone else's recipe, one of the things you should do is scale the grain bill up or down, so that it's sized to achieve X and Y with the efficiency that you expect in your brewhouse.

Thanks for responding by the way. Yes you are reading my first post correctly now.

So to use your example. Someone shared a recipe they have made. That recipe has 5G - 12lb Grain - And a target OG. If I recreate that recipe as detailed, my BHE would be exactly the same would it not. So how would I know how to scale the grain bill accordingly? Each brewhouse obviously has different grain absorption rates, boil off rates etc. But AFAIKT none of that is taken into account with BHE which is why I was asking the question.

I guess I am lucky in that I have hit my 5G and OG for the first 3 BIABs I have done. So my BHE is basically 'as the recipe'. I read about people wanting to improving BHE all the time, but if you are hitting the marks then it will always remain the same for that recipe.

I am sure I am not understanding something.

 

[VikeMan]

So to use your example. Someone shared a recipe they have made. That recipe has 5G - 12lb Grain - And a target OG. If I recreate that recipe as detailed, my BHE would be exactly the same would it not.

If you recreate that recipe as detailed, and hit the same OG at the same fermenter volume as specified by the recipe, then your brewhouse efficiency would be the same as the recipe author's implied brewhouse efficiency. But more often than not, that won't happen, because your own efficiency is likely to be higher or lower than the author's.

So how would I know how to scale the grain bill accordingly?

By experience with your brewhouse. And once you know what kind of efficency you get with a grain bill of "N" pounds, you can estimate the efficiency to expect from grain bills of other sizes.

Each brewhouse obviously has different grain absorption rates, boil off rates etc. But AFAIKT none of that is taken into account with BHE which is why I was asking the question.

Ah, but grain absorption rate (and lots of other things) do affect brewhouse efficiency. Some other things are fineness of malt grind, non-recoverable deadspaces in the mash tun, wort transfer losses between the mash tun and the kettle, wort transfer losses between the kettle and the fermenter, and hop absorption.

I think part of your confusion is separating the implied efficiency embedded in a recipe's numbers from an actual, measured, achieved efficiency.

 

[thomer]

I think part of your confusion is separating the implied efficiency embedded in a recipe's numbers from an actual, measured, achieved efficiency.

You are right. I need to study it more. Thanks again for the responses.

 

[CascadesBrewer]

I guess I am lucky in that I have hit my 5G and OG for the first 3 BIABs I have done. So my BHE is basically 'as the recipe'. I read about people wanting to improving BHE all the time, but if you are hitting the marks then it will always remain the same for that recipe.

Many recipes are written for a fairly "standard" BHE of around 70% to 75%. If your system lands in that sweet spot, then you can often brew published recipes without adjustment. On the other hand, if your system was getting 65% or 85%, you would likely have to make adjustments.

 

[thomer]

Many recipes are written for a fairly "standard" BHE of around 70% to 75%. If your system lands in that sweet spot, then you can often brew published recipes without adjustment. On the other hand, if your system was getting 65% or 85%, you would likely have to make adjustments.

Good advice. Thank you.

 

[CascadesBrewer]

Good advice. Thank you.

I would add it is a good idea to understand your efficiency and to understand the factors that drive your efficiency. Some batches, like a high gravity stout or an IPA with 8 oz of hops in the kettle, will force your BHE away from your "normal" level. You will also find recipes that are written for a different efficiency and recipes written for a different process.

It is also not wrong just to know "if I mix 10 lbs of grain with 8 gallons of water, I end up with around 5.5 gallons of 1.050 beer into the fermenter."

 

[marc1]

If you measure volumes and gravities throughout your process, you can get the parameters needed to better predict things.

You can get a better feel for things if you learn some brewing software and input these values, then play with different grain bills, volumes, losses, etc. to see how they affect the overall process.

 

[cactusgarrett]

Many recipes are written for a fairly "standard" BHE of around 70% to 75%.

This is why it's a good practice to discuss recipes in terms of % of grainbill (instead of absolute weight) and IBU contribution (instead of weight). Everyone's efficiencies and hop utilizations can make a recipe based on weights turn out different.

 

[brewfun]

So to use your example. Someone shared a recipe they have made. That recipe has 5G - 12lb Grain - And a target OG. If I recreate that recipe as detailed, my BHE would be exactly the same would it not.

It might not be the same, unless you hit both OG and fermenter volume the same as the original brewer. Mash extraction efficiency is the first part of BHE. The second part is the losses that are unique to your equipment and methods. BHE is then "Mash Efficiency" multiplied by "Fermenter Volume Efficiency" expressed as a percentage.

The first part is fairly straightforward and it seems you understand it perfectly well. It's the second part that is not making sense to you.

If batch volume is measured in the kettle, post boil, then mash efficiency is the same as brewhouse efficiency. There are no losses to consider, so the volume efficiency is 100%. But if you measure batch volume in the fermenter and if your equipment holds 0.5 gallons of trub you consistently leave behind, you now have a volume loss to consider, which will lower BHE. Trub loss of 0.5 gallons for 5 gallons means you're harvesting 90% to the fermenter. With that loss and a mash efficiency of 75%, results in a BHE of 67.5%. In other words, 67.5% of all the available sugar will end up in the fermenter. The final fermenter tally would be 4.5 gallons at 1.068.

So how would I know how to scale the grain bill accordingly? Each brewhouse obviously has different grain absorption rates, boil off rates etc. But AFAIKT none of that is taken into account with BHE which is why I was asking the question.

Suppose the recipe you purloined from the club meeting is based on the above BHE, but your BIAB only gets 65% mash efficiency, and holds 0.75 gallons of kettle trub. Add to that, you want 5.5 gallons in the fermenter to account for yeast and racking loss in order to get a full 5 gallons into your keg. Obviously, you will need 6.25 gallons, post boil. If you follow the recipe exactly, you'll end up with 5.5 gallons at about 1.050 to ferment. Your BHE with the change in extraction, volume and losses is 57.2%. Here's where the scaling needs to be with BHE, not just mash efficiency because to get the correct gravity AND volume, the ONLY place it can come from is increased mash efficiency. As you pointed out, your efficiency is somewhat fixed and predictable, so that's not likely to happen. Therefore, covering losses as well will give you the correctly scaled grain weight to get the intended OG 1.068.

 

[thomer]

@brewfun great explanation. Thank you..