Demand
From Frostpunk 2 Wiki and Guides
Demand is a term used by the game to refer to the resources and other supplies which are used to operate Districts. There are two categories: Demand and Requirement.
The main Demands in the game are 
Heat, 
Materials, 
Food, and 
Shelter. 
Workforce employment requirements are also a Requirement for operating districts.
Demands are fulfilled from active daily/weekly production. Requirements are taken first, and then all other Demands. If this is not possible, resources will be taken from stockpiles to try and fulfill the remaining balance.
If resources are at a deficit and it is not possible to satisfy all demands, then Problems may arise in the city.