How much food and goods does a house consume per year? Usually you need an answer to that question if you want to know how many patrician houses you can support with the limited number of imported exotic goods.
One load of food and goods in your granaries, warehouses, and markets gets converted to 100 units when it arrives in a house. Food and goods are consumed in "consumption cycles" of three weeks, and there are 16 consumption cycles a year: in Caesar IV there are 48 weeks per year.
Each pleb or equite living in insulae or domus eats 0.8 units of food per consumption cycle, or 12.8 units per year. If a house has two or three food types, your people won't eat more per month, but will eat about half of each food in case of two types, or one third in case of three types.
Actually, the number of units of each food type eaten per cycle is proportional to the number of units stored of each food type. For example, if a house has 100 units of grain and 200 units of vegetables, the occupants' meal will consist of 1/3 grain and 2/3 vegetables. If the numbers have to be rounded, the house will favour grain over vegetables and meat, and will favour vegetables over meat.
This feature can be exploited if you have enough grain available, but have limited access to vegetables or meat. First, give all houses access to all food types. Then, only let them have access to grain. What will eventually happen is that the house has 250 units of grain, 1 unit of vegetables, and 1 unit of meat. Due to rounding, the people in the house will only eat grain and leave the vegetables and meat alone. They will think they have three types of food but consume only grain, as long as there's enough grain available. Depending on how much food is consumed per consumption cycle, the "stable" stock of meat and vegetables can vary between 1 and 3.
Plebs and equites will try to keep between 200 and 300 units of each food type stored in their insulae or domus, patricians will try to have a stock of 100 to 200 units in their homes.
Basic and luxury goods are consumed by all houses at the same rate of 12 units per consumption cycle (apart from plebs, who don't use any luxury goods). The same proportion as for food holds: if the house has 100 pottery and 200 glass, it will use 4 units of pottery and 8 units of glass during the next consumption cycle.
Exotic goods for patricians are a little different: villas and estates consume them with a rate of 12 units per consumption cycle, just like basic and luxury goods. From small mansion onwards, they consume double that rate: 24 units per consumption cycle. Again, the same proportion calculation holds.
The table below shows the number of units per consumption cycle and loads per year a fully occupied house consumes. Goods are only listed if the house really needs them. However, if you give, for example, a small villa access to exotic goods, it will consume them anyway, regardless of whether they actually needed the good for upgrading their home.
|Housing level||Per cycle (units)||Per year (loads)|
|Food||Basic goods||Luxury goods||Exotic goods||Food||Basic goods||Luxury goods||Exotic goods|
|Small, Medium, Large Villa||36||12||12||-||5.76||1.92||1.92||-|
|Small, Medium, Large Estate||36||12||12||12||5.76||1.92||1.92||1.92|
|Small, Medium, Grand Mansion||36||12||12||24||5.76||1.92||1.92||3.84|
Food consumption of Forts
Cohorts living in forts need food: if they don't get their share of food, they'll refuse to fight or even desert. Each soldier in a fort eats 6 units of food per consumption cycle, so a full cohort of 20 soldiers eats 120 units of food per month, or 19.2 loads per year: the same as a fully occupied large insula does.