I’m going to talk about a more uncommon form of hop addition, first wort hopping or FWH as you might see it referenced as. There are some interesting things about this technique that make it very useful as a hop addition method. hopefully FWH can be a great addition you your brewing expertise.
This is a relatively unknown topic for some home brewers. First wort hopping is a great way to achieve bitterness as well as aroma in your beer. It might go against your hop addition knowledge but you will receive aroma from a first wort hop addition. From experience, the bitterness is a little less harsh and smoother than that of hop addition right after the hot break.
This technique has been around for a long time but wasn’t used much, especially in the States. It actually began in Germany and had been mostly forgotten and wasn’t written about again until 1995. This is when the first of many articles started to come out explaining first wort hoppingby Priess, Neuremburg and Mitter in Brauwelt International, Vol IV.
First wort hopping is achieved by adding the hops to your kettle at the very beginning of sparging. They will experience a steep in the hot sparge water and then the range of temperatures leading up to the boil as well as the boil. As soon as you have cleared the first running you should add the hops and leave them for the rest of the boil.
The way it works is that having the hops in the brew kettle during sparging helps reduce the pH of the 
mash and sparge to allow enhanced isomerization of the hops in the boil. This will make your hops more efficient in the boil giving you more utilization. You will notice an 8-10% increase in the IBU’s of the hops you use compared to if they were added at the hot break. You can calculate them yourself, or Beersmith does account for FWH in its calculations.
For first wort hopping it is recommended that you use low alpha acid hops, like aromatic or noble hops. High alpha acid hops might prove to add too much bitterness to the beer. There are many different techniques on which hops and how much you should add. Some techniques say to take a small percentage (20-30%) of your hops for the entire boil and add them for FWH. Some say to just move your aroma hops from the last part of the boil to FWH. Some lighter beer can even be entirely hopped by the first wort hopping method.
This is an interesting technique that should prove valuable for you if you plan to use it. Give it a try in your next brew and see what you think.
