The EM still ferments at room temp., but after reading Vinny's stuff, it SEEMS that it takes expert brewing to get the extended EM at the same quality as the original batch. For me, I want to take the EM for probiotic purposes. And I don't know if fermenting it at room temp. for a week is gonna get me the same amount of probiotics as the mother culture. That's what I want to know. Otherwise, it's not really worth brewing. If it really takes expert brewing (brewing at a constant 98-104 degrees for 2 weeks to 2 months), then it's really not worth extending since you're burning a hole in your pocket with the heating bill.