Population and Happiness
In order to successfully operate a Settlement in Brunelleschi, it is necessary to understand the mechanics of Population, Happiness, and Housing. By managing these variables you can custom tailor your Settlement's economy and culture, putting your own distinct leadership philosophies to work with not only NPC simulated citizens, but actually Human Player Heroes and Lords.
New Citizens Immigrate to the Settlement based on the following formula. Immigrants = (1/8th of the available space * the current average settlement happiness as a percentage) + 2 .
Homeless and/or Unemployed Citizens leave the settlement at a rate of 15% of the Peasants, 30% of the Yeomen, and 50% of the Peers. In small settlements this may not even be noticeable in the population numbers.
Classes of Citizen
Humans in the western world mostly used 3 basic tiers of society after the fall of the Roman Empire. In our societies we tend to refer to these as 'upper , middle, and lower class'. In the Renaissance, the Bubonic Plague had created unprecedented power for the lowest class, hugely increasing number of 'Middle Class' individuals doing business, owning houses, and clamoring for political power. The defining rule of the Dark Ages had been concentration of power at the top with almost no Middle Classes to speak of (sound familiar?). Ursinia Pestis changed all that, making Labor expensive in a way that had not been seen before.
How does all this history impact the game? Well Citizens aren't just going to accept Serfdom anymore, you have to give them nice places to live, even the Peasants, and they're going to demand 5 things from you quite strongly! You'll have to spend some portion of what they create for you on their needs, or they're going to make your Reign miserable.
The Hardy Peasant, salt of the earth and worker of the land. You won't get far without them, and they don't care much for Lords who squander their output. Peasants like cottages, will cram into Tenements, and are inclined to settle naturally around the Grainery, as are all other Citizens. Your heavy industries and resource gathering buildings are going to use up a lot of these guys, but fortunately they don't have a huge impact on happiness. They'll put up with low-quality services if you at least build a few chapels, though well educated and healthy Peasants build much faster than sad, starving ones. It's your call, but be prepared for Riots, Plagues, and waves of Ignorance if you ignore their needs too much. Peasants make for cheap, fragile troops. Don't send the Fyrd or Militia into battle without preparing for some casualties. Peasant soldiers need only food and Bronze coins to stay loyal, so they make good Garrison troops for mostly peaceful settlements.
The Diligent and Moral Yeoman is your middle class citizen. A nod to the unusually egalitarian social structures forming in the traditionally repressive culture of England, the Yeoman (or Townsman) is a crafty, useful person. They've trained in a trade and expect better housing than the lower classes, Apartment Buildings and Houses are their preferred dwellings, though other more exotic structures will bring them in. Any upgrade to the Grainery will inevitably bring more to your Settlement as well. The middle class is essential to Crafting, Production, and Administration and a well tended Yeomanry will make you wealthy with silver coins from Pubs, Auction Houses, and the Forum.Yeomen expect better treatment and use up a greater amount of your happiness services than Peasants. You'll need to build Chapels and Libraries to satisfy their greater need for stimulation. Yeoman units like the efficient Crossbowman or the hardy Trooper can survive more damage and equip more Gear than Peasant troops, but they want Silver for their pay and more food variety as well.
Snooty Peers have worked hard to get ahead in life and they don't live just anywhere. Expensive buildings are needed to bring them to your Settlement, or large grants of Land which they will not share much of the output from. Latifundia are the basis of any early settlement, as the Sovereign has little to offer Peers other than territory and workforce. Peers gobble up Happiness points and won't settle for overcrowding at all. They'll be a pain to recruit for much of the game, with expensive Mansions buildable anywhere but generally other Peer housing is District exclusive, though there are 2 options for that in the early game. The Villa of the residential district isn't cheap, but on the plus side the Marble and Stonecutter infrastructure you create will also help create the coveted Marketplace. Peers make terrifying troops, but are of course the most expensive to recruit as Cataphracts, Thegns, Charioteers, and a dozen more elite gold hungry Peer Units.
Your Human Player Citizens will need places to live as well. The grainery offers a 10 person initial limit, so that teams can get assembled and started. Harvesting enough Grain to get another grainery level shouldn't be too hard, so getting a 20 person settlement going might take as few as 2 or 3 days for a dedicated group.
These are special cases of course, but they do use up a population slot. You can recruit a minister if your settlement is 'Full', but you won't be able to recruit more until you're back under your limit. Ministers also gain control of a whole district including output and storage. If you want some of their product directly as a Sovereign, you'll need to set Taxation on Harvest Buildings in the government screen.
There are 5 essential types of Happiness, and a 6th non-essential type. They each have wildly different effects on a settlement. Happiness is determined in ways so complicated they'll have to be the subject of a whole post later, possibly by the programmer.
The Security rating of a district is essential especially to Peers, who always suspect the lower orders of coveting their wealth (perhaps rightly so). Raising Security will also decrease the success chance of Illegal Actions in that district, or for higher level actions the Settlement aggregate security rating will be used. Riots and Crime are the inevitable consequence of lowered Security, and many hostile or disreputable actions will temporarily lower the security of a district. An especially secure settlement will tend to have Parades.
Health is an important aspect of city management, and as such you'll want to make sure plenty of Orchards, Hospitals, and Fountains are built in your settlement as soon as possible. Plagues will occur when this falls below 40, so try to avoid that if you can. If the rating goes above 80, the people will be more likely to have a carnival, after all it's easier to celebrate the flesh when it's healthy.
Poverty really saps the joy out of life for most people, and the growing affluence of the 1500s is reflected in the Population's demand for goods and services. Build them lots of Bazaars in the Marketplace and keep them upgraded! Poor Citizens (Prosperity < 40) will suffer more Famines, as they cannot afford good food or storage facilities. Above 80 prosperity, however, spontaneous Fairs will break out, providing rewards to player Citizens who participate in them. District Prosperity modifies building cost, so keep it above 50 to avoid paying more for buildings.
An educated populace builds things more quickly, and this can really become important on later Building projects (some buildings take weeks to upgrade). A wave of Ignorance will afflict Districts that fall below 40 in this value, while those above 80 will enjoy Festivals of art and culture.
The Faithful reject heresies and it is harder to conduct Necromantic experimentation or Judaic research into the origins of Christianity when the Faith rating is higher. A District falling below 40 in this value will fall into Heresy, rejecting the right of the Sovereign to rule as an agent of God. Districts going above 80 will experience Holidays paid for by the Church.
Respect is not necessary, but it brings up average happiness without being required, making it a 'Buffer' against negative consequences of a low total score. Settlements can use Statues initially to raise this value, and eventually buildings like the Senate or Piazza Del Signoria will allow pervasive use of the bonuses.