Storage conditions for the time between harvest and purchase.
This constant is ours, not Garetz's, and like the 0.05 packaging factor it's
an assumption that affects IBU. Garetz models one span under one set of
conditions, because in 1994 the question was how long the brewer had had
the hops. With a crop year we also know how long the hops were in the trade.
Using the brewer's own storage for that time would charge them eighteen
months at cupboard temperature for hops that spent it at 2 °C under nitrogen
in a merchant's cold store.
The figures are typical conditions between harvest and a homebrew shop's
shelf: baled or packed under inert gas and held just above freezing. They're
conservative, since a real cold store is often colder, because the mistake
we most want to avoid is telling a brewer their hops are fine when they
aren't.
Storage conditions for the time between harvest and purchase.
This constant is ours, not Garetz's, and like the 0.05 packaging factor it's an assumption that affects IBU. Garetz models one span under one set of conditions, because in 1994 the question was how long the brewer had had the hops. With a crop year we also know how long the hops were in the trade. Using the brewer's own storage for that time would charge them eighteen months at cupboard temperature for hops that spent it at 2 °C under nitrogen in a merchant's cold store.
The figures are typical conditions between harvest and a homebrew shop's shelf: baled or packed under inert gas and held just above freezing. They're conservative, since a real cold store is often colder, because the mistake we most want to avoid is telling a brewer their hops are fine when they aren't.