To convert from cubic meters per hour to liters per hour, you need to multiply the value in cubic meters per hour by the conversion factor 1000. This is because there are 1000 liters in one cubic meter. So the conversion would be as follows:

12 m^3/hour * 1000 liters/m^3 = 12000 liters/hour.

Alternatively, you could write the conversion as follows:

12 m^3/hour * (1000 liters/m^3)/(1 hour/3600 seconds) = 12000 liters/hour.

In this case, the conversion factor is derived from the fact that there are 1000 liters in one cubic meter and 3600 seconds in one hour. This allows you to cancel out the units of cubic meters and seconds, leaving you with the units of liters per hour.