I can actually get small thermistor based hot wire anemometers for about a dollar, so I can just use those with a PID control loop to control fan speed. Then the flow is quite well regulated. However high winds will overwhelm the fan, a problem you don't have so much with centralized units, however that's because the fans are so powerful in centralized units. This implies quite high electrical energy consumption and also noise production. The noise production is not as bad because the fan is in your basement or whatever, but it's still serious and not as good for the most part as a well designed, flow compensated decentralized unit, even for the flow vs noise ratio. I added an automatic valve which only costs about $30, which closes in a storm. So as long as most of the time the wind isn't crazy everything works pretty good with the decentralized approach.