I assume you are using E+
I did something like that for calculating the amount water my future garden will consume :
I started by calculating the dripperline flow per minute.
![image description](/upfiles/15245936802451696.jpg)
Then I estimated the amount of water the garden will consume each month. (I used government calculator which take rainfall into account).
![image description](/upfiles/15245937397089303.jpg)
You should use the cubic meter per hour number and divide it by your roof irrigation surface area to get the irrigation rate [meter per hour]
Now for the question you asked - you can look in the YourDriveLeter:\EnergyPlusV8-8-0\ExampleFiles\EcoroofOrlando.idf example of E+
! Schedule for irrigation (1"/irrday summer 0.5"/irrday winter: Mon and Fri at ~10am)
! Note: UCF documentation inconsistent 1 vs 2 " in summer per week??
! To avoid stability issues with 1hour timesteps we simply add 1/7th of weekly
! precipitation evenly divided into 2 hours each of ALLDAYS each season
! Note: 0.00181 in*2hrs*7days = 1 inch per week
! m/hour
Schedule:Compact,
IRRIGATIONSCHD, !- Name
Any Number, !- Schedule Type Limits Name
Through: 3/31, !- Field 1
For: Alldays, !- Field 2
Until: 07:00,0.0, !- Field 3
Until: 09:00,0.00181, !- Field 5
Until: 24:00,0.0, !- Field 7
Through: 12/31, !- Field 9
For: Alldays, !- Field 10
Until: 07:00,0.0, !- Field 11
Until: 09:00,0.00242, !- Field 13
Until: 24:00,0.0; !- Field 15