ASD

Active Subsoil Depressurization

ERV

Energy Recovery Ventilation

ASD is designed to prevent radon gas from entering the home by sucking it from beneath the foundation. 

However, in some buildings ASD just won’t work due to problems such as: lack of gravel below the slab; suction pipe clogging; soil that’s too compacted or wet; a multi-level or divided foundation; a drainage pipe within the foundation; or inadequate crawl space. In older homes there may be too many radon sources. Etc. Etc. Etc.

EVP, on the other hand attacks Radon in the interior air, purifying the entire air supply, making it the perfect solution for jobs where ASD won’t work. Radon gas can’t escape AND indoor air pollutants are eliminated, as well. Purity².

IAQ Comparison

DIFFICULT JOBS WHERE PURITY² CAN SOLVE THE PROBLEM:

  • Situations where ASD won't work due to subsoil clay, wetness, lack of porosity.

  • Situations where crawlspace clearance is inadequate to mitigate.

  • Situations where homes over 50 years old have too many radon sources, earthen basement, slab over soil.

  • Situations where home/building footprint is very large, on many levels, or different foundations, requiring numerous ASDs.

  • Situations where ASD can only reduce radon partially, not the final mile.

  • Situations where construction and finish materials are a major source of radon, like natural stone.

  • Schools and commercial buildings with complex layout and isolated areas.

  • Where radon is one of many lAQ issues.