Excel 2007 : Summing up groups of number separately?

Help needed. Let say I have sample data as in example.xlsx attached and I want to sum up those between 0s (zero) only and separately. From the sample, they should be from A3:A8 then A12:A14 then A18:A22 and so on. Is there a formula to do it? I can't key-in the SUM function one by one because I have more than 10000 rows with 24 columns to do so:-) Thanks in advance.