All the buildings give points based on the length of time the building is crafting. Any item that does not take at least 1 hour will not generate any points UNLESS you have several items in the queue and do not collect until after they have all finished. Then you will receive points based on the total amount of time spent crafting.
For example, with regards to the Windmill:
1 Flour (10 minutes) - no points
1 Sugar (20 minutes) - no points
1 Powdered Sugar (30 minutes) - no points
1 Almond Flour (30 minutes) - no points
1 Brown Sugar (40 minutes) - no points
1 Corn Starch (1 h 30 minutes) - 1 point
1 Shaved Truffles (1 h 30 minutes) - no points [NOTE: this is an anomaly; by rights it SHOULD give 1 point, but it does not]
2 Flour (20 minutes) + 1 Brown Sugar (40 minutes) = 1 hour = 1 point
2 Corn Starch (3 hours) = 1 point + 2 point
(1 point for the first hour, 2 points for the remaining hours - 30 minutes from the crafting of the first Corn Starch + 1 h 30 minutes from the second)
The Dehydrator works in the same way.