For generations, brewers in western Norway have fermented their farmhouse ales with a family of yeast called kveik. Each brewer’s culture is a living heirloom. “You’re brewing the same beer that your dad brewed and his dad brewed,” said Lars Marius Garshol, the Norwegian author of “Historical Brewing Techniques: The Lost Art of Farmhouse Brewing,” out in April. “It was nothing special.”

He discovered that kveik contradicted fermentation’s commonly understood framework. Most beers are fermented with one strain. Kveik is a “choir of yeast,” potentially dozens, that fast-tracks fermentation. Beer can be drinkable in as few as two or three days, compared with the two weeks required for ale yeast.

More curiously, kveik ferments at up to 100 degrees and produces sweet, fruity aromas. (Hot fermentations usually stress yeast and smell like solvents.)

Several years ago, Mr. Garshol said, he shared kveik samples with U.S. yeast suppliers such as Omega, hoping to “present the brewing world with a new universe of flavors, methods and traditions.” Now, American brewers are increasingly embracing kveik’s unique qualities.

Mr. Schaaf, of Ebb & Flow, makes his beers almost exclusively with varieties of kveik. He ferments them hot, by default and design — the brewery was built without temperature control for fermentation.