Exhibit 1: Horizon Zero accounting guidance helps aluminum producers better differentiate their decarbonization efforts on processing virgin materials, compared with the current accounting method.

The current carbon accounting system results in similar emissions profiles for both products A and B, because they are made with different fractions of virgin and recycled inputs. Horizon Zero guidance provides more emissions transparency that can reveal the emissions intensity tied to processing of virgin input materials, which is not captured in current accounting methods. Our guidance also can help aluminum producers transparently demonstrate their decarbonization efforts on processing virgin materials at the product level, gaining a competitive advantage in the low-carbon commodity market.