450-550 is great, especially since ambient levels outside are about 420. I live in an old house and with windows closed and no hvac fan running, rooms only take

450-550 is great, especially since ambient levels outside are about 420. I live in an old house and with windows closed and no hvac fan running, rooms only take about 30 minutes to get up to 800ppm with one person in them. After an hour or two they get up to about 1050ppm. With two people, they get > 1000 pretty quickly. Looking at metrics from the sensor is pretty interesting too. You can see, to the minute, when a room went from unoccupied to occupied.