For a long time, I regarded windmills as a niche improvement... mostly used for marginal cities that couldn't grow to a decent size without, in the rare game where Environmentalism actually looked competitive compared to State Property or corporations under Free Market, or to get the FIN bonus on riverside hills. Recently I've come to appreciate them very much even without the bonus, since they make almost any heavily optimised economy stronger: *** When running State Property+Caste System, relying on farms and mines is wasteful: workshops -> farms and mines -> windmills both convert hammers into food at a 2:1 ratio, but in the case of winmills we get some thrown in to sweeten the deal. Hence, mines are only used in cities with excess food in which we don't wish to run (more) specialists. *** In case 17 towns are available, things become quite interesting for lategame optimisation. Standardising for food neutrality for 4 tiles, 2 grasslands and 2 grassland hills: 1 farm, 3 towns gives us 521: running as many of those yummy towns as possible is definitely strong! 1 farm, 1 town, 2 mines gives us 97. Giving up 3.5 per is not good; more towns and rushbuying is almost strictly better unless we have compelling reasons for wanting straightforward production (Heroic Epic + Military academy, needing to build projects). 2 towns, 2 windmills gives us 618-22. Outright better with Environmentalism; worth considering even if we don't plan to end up there since we can grow the towns early (before Biology and when caps are restrictive) and work the windmills later - unlike cottages, they start out strong. * Now the same situation, only with plains hills - uncottageable and requiring a full Biology farm in support. 2 towns, leaving the hills idle: 214. 2 farms + 2 mines: 10. Is this better or worse? Not so sure myself but not as blatantly suboptimal as grassland mines. 1 farm + 1 town + 1 mine: 67... the compromise between the options above. 1 farm + 1 cottage + 2 windmills: 711-15. Generally the most attractive option, with or without Environmentalism. If the caps aren't an issue, this is probably worth it even with desert hills and without Environmentalism (511). *** If I set my economy up for heavy Kremlin-assisted whipping, I can be assured of a decent return of hammers on spare food. Even at size 20 (average during regrowth so maximum in the low 20ies), 1 whipped is theoretically worth 1.5:hammers and getting 4 for every sacrificed sounds good to me. This depends a little on the state of our growth caps and the quality of the marginal citizens to be whipped away (usually specialists). The latter isn't a problem under Representation as the average specialist output is worth more than 3 in most circumstances.