Back in August I got a radon measuring device, it has been interesting to watch radon levels go up and down and trying to figure out why.

My best guess is barometric pressure. Comparing Radon and Pressure charts (see attached) they seem to line up, perhaps radon lags pressure changes because I think the half life on Radon is about 2 days.

In early November when we closed up our windows for good for the winter season here in Colorado I noticed the peaks and valleys became more even. Then I got to thinking, does a passive house have less pressure changes because it is so tight?

My house is 5.9ACH50 the last time I tested it. I have been doing some air sealing but I doubt is it lower than 5ACH.

Also we do have an active radon fan.