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What is an HBU Pack?

HBU stands for Home Bittering Unit.  It is also known as an Alpha Acid Unit. 

Developed as a method of standardizing the total bittering potential of hops in order to mitigate the variation in Alpha Acids from season to season and hop to hop.

HBU is calculated by multiplying the amount of hops (oz) by the Alpha Acids.  (oz x AA% = HBU)

Example: 1 oz of Northern Northern brewer at 9.6% Alpha acids is 9.6HBU’s
Example Formula:  1 oz * 9.6 AA% = 9.6 HBU

When Did We Start Using HBU Packs In Our Recipes?
We began March 1st, 2017.

We researched our recipe quality against the changing Alpha Acids of the Hops each season.  Each year AIH needed to update and change over 1200 recipes to keep the desired IBU consistent with the current crop of hops and their Alpha Acid%.  In many cases this was an impossible task leading to inconsistent bittering hop additions from season to season.  The result is a recipe that is going to be inconsistent from brew to brew.

Every homebrew supply store that does not calculate and update their bittering hop additions with every AA% change is suffering from the same deficiency.  
As the largest provider of designed homebrew recipes, AIH took action to guarantee quality & consistency. 

Creating and using a specific HBU pack guarantees consistency in bittering from brew to brew for a particular recipe without affecting any other aspect of the recipe.

How Were HBU’s Calculated?

Most AIH Recipes are designed to the 2008 BJCP guidelines and assigned the appropriate category (eg 13B).  
When calculating HBU’s for our recipes, AIH used this categorization to calculate the correct level of IBU’s by style and convert that bittering potential into Home Bittering Units. 

This number was then confirmed using the target alpha acids of the existing bittering hop and converting that to HBU.  

Recipes assigned style 23 (open style) or no style had the HBU units calculated using the target alpha acid of the existing bittering hop being used in the recipe.  

Formulas for IBU to HBU and Back: Using these formulas we can calculate everything that is needed once we have target or measured AA%:

IBU Regular: IBUs = U% * (ALPHA% * W_OZ * 0.7489) / (V_Gal)
IBU From HBU: IBUs = U% * (HBU * 0.7489) / (V_Gal)
Variables:
  • V_Gal: Boil Volume
  • U%: Hop Utilization
  • 60 minute boil addition = 31% Utilization (no additional utilization (isomerization) above 60 minutes)
  • 45 Minute boil addition = 26.9% Utilization (no additional utilization
  • 15 Minutes: 8% Utilization (no additional utilization
  • 5 Minutes: 5% Utilization (no additional utilization
  • .7489: Constant
  • HBU = AA% x Weight_Oz

Will using the HBU instead of the original bittering hop change my beer?

NO, but it needs a little explanation. (95%+ Of recipes were converted to HBU)
In cases where it was deemed that a straight change to HBU would change the beer beyond it’s original goals, those recipes were not changed.  In all there are less than 60 out of 1200 recipes that were not changed because of this reason.  (examples include Pliny the Elder, Bell’s Two Hearted Ale, Heady Topper and other clones...that were not changed).

In cases where the bittering hop is known to carry into flavor and aroma, that recipe was left alone.  This is exceedingly rare (one example are hops like chinook.  Chinook has an intense piny flavor and aroma that will carry over from bittering into flavor and aroma).