Happiness is something you'll want to pay attention to. You'll always want to have enough happiness to get the maximum wealth out of your Empire. Happier citizens will pay more taxes and work harder for you, if they're enthusiastic you'll recieve a whole 20% bonus Gold and Supplies.
This does not affect Goods Buildings.
Seems that to have over 120% happiness level, your Given Happiness over Requested Happiness should be over 1.4 (140%).
- If ratio > 1,4 then Happiness = 120%
- If 1,2 < Ratio < 1,4 then Happiness = 100 %
- If 1 < Ratio < 1,2 then Happiness = 50%