I assumed they meant 1/5 less. As in- uses 80%. 20% reduction. If you have 5 logs, you only need 4.I am not sure what they are comparing it to, but the 1/5 of the wood number is completely a fallacy. Even if my stove is 50% efficient (which it exceeds) and the MH was 100% efficient (which it is not)...that would only be a reduction of 50% consumption.