For many beers, aging allows flavor development and evolution, just as with fine wine. For example, hop character can mellow and integrate with evolving malt and yeast aromas and flavors, highlighting desirable nuances that are masked or not present when the beer is new.
Oftentimes, breweries will provide suggested aging parameters—including ideal temperature and maximum length of aging time—right on the label. Candidates for cellaring/aging are typically bottle conditioned beers with an 8 percent ABV or higher, although exceptions exist.
As for the best beer storage position (upright or lying down) there is no single definitive answer—no right or wrong. Again, bottle instructions may specify a brewer’s preference. Most beer experts recommend upright storage, especially for bottle-conditioned beers, allowing yeast sediment to settle at the bottom of the bottle where it can be poured into the glass or left in the bottle at the drinker’s discretion.
The most important factors for aging include temperature and darkness. Ideal beer cellaring temperature is generally in the 50-55 degree Fahrenheit range, with protection from long-term light exposure highly recommended. In the absence of a true cellar environment, a cool, dry, dark place, such as in a box in a closet may suffice. To avoid constant temperature fluctuation, rule out the garage for a makeshift cellar for any type of beer. A refrigerator is always a safe place, although cold refrigerator temperatures will markedly slow down—and perhaps even stop—the desired aging process for beers you are truly trying to “cellar.”