Be careful with this one. If you see a house/apartment where lights are repeatedly being turned on/off that’s generally considered a signal that they are in distress and you might get first responders dispatched to you curtesy of a neighbor who saw this and called 911.

Also I honestly can’t think of a worst way to try to save money, especially after you factor in the power it might take to do the facial recognition. There would be a good chance that you actually lose money unless you are in a hanger full of Na lights.

Edit: 5 bulbs in a room that each consume 10 watts (fairly generous), people blink up to 20k times a day, an average blink is 100 ms. So that’s 2000 seconds of blink time or just about 33 minutes. 33*5*10 is 28 Watt-hours saved per day or about 0.84 kWh per month. At the rate of $0.20 per kWh you just saved $0.16 a month.

But wait you have latency to detect the blink so let’s cut that figure by 15%. And since we don’t know how long a blink will last (some are shorter) you also need to reduce the off time by one standard deviation of a blink so to be safe let’s make the off period after detection last only 60 ms. So now we are at $0.096 per month. And now we also need to run multiple cameras and facial detection which has to run continuously. Unless you can do that under 28*0.6=16.8 Wh per day you are losing money.