Efficiency upgrades

Factories, shops, and offices have a percentage that will decline by .02% on the first day, .04% on the 2nd day, .08% on the 3rd day and so on. Factories can get upgrades(see Factory Upgrades) that will increase their overall production, but shops and offices cannot.
Please note the efficiency will be effected by upgrades.
The game does a calculation each day based on the previous day's efficiency. The actual formula used is:
new efficiency = previous effeciency - (building age * 0.0002 * base efficiency)
When you do an efficiency upgrade, both the current and base efficiency are bumped up by 20 percentage points.
Tycoon Online FAQ