AARST_Radon_Reporter_Q42025

6 | DECEMBER 2025 Believe the Numbers Chad Robinson, Building Performance Company Data, numbers, are the backbone of radon mitigation. This is especially true in difficult to fix buildings. All too often in our industry, mitigators get lucky and their systems reduce radon concentrations without measuring any pressures. These systems, even though they are “working” are most likely oversized, creating unnecessary energy penalties and unnecessary noise. According to Brian Hanson, Kansas State University Engineering Extension, one of the National Radon Hotline’s most common calls is about noisy radon systems. The National Radon Hotline also fields calls from mitigators that are having trouble with “buildings from heck”. The most common reason the building is a problem to fix is because of lack of pressure field extension (PFE) data. In my experience, we could get lucky (poke and hope) and “fix” 8-9 out of 10 single family residences. If we loosened our definition of “fix” to mean 1) get radon concentrations to 3.9pCi/l, 2) fan energy use does not matter, 3) added ventilation does not matter, 4) noise, significant enough that home owners notice it, does not matter, and 5) we become slightly selective on jobs we take (weed out the difficult ones), we could probably get that number to around 9.5 out of 10. But that is still a 5% failure rate and a lot of noisy, expensive to operate systems.Five in 100 failures, in my opinion, is terrible results. And I believe the failure rate would be closer to 20 in 100, if we tried to optimize systems for effectiveness, energy efficiency, and noise, without data. Anyone that has heard myself, or Josh Kerber and I, give a presentation in the last few years, knows that we have been trying to bring awareness to the epidemic surrounding the lack of data-driven decisions in radon mitigation. I have been fortunate enough to work with Josh, Bruce Snead, and many other conscientious mitigators from around the country over the last few years. I think I can speak for all of us when I say, it is incredibly frustrating to see mitigators struggling to fix houses, oversizing systems regularly, and installing ERV/HRV’s when they are not needed. For me, the great and hopeful thing is that there are some conscientious mitigation professionals in the industry that care about maximum radon reduction while properly sizing systems. These same professionals fix 100% of the homes they work on with active soil depressurization (ASD) (unless there is a water or emanation source). What follows are a couple examples of houses that I would have had to give up on if I had not had data to direct my decisions. I think they highlight the importance of understanding how to collect and interpret PFE, sniffer, and radon concentration measurements. MITIGATION