K-12 School — Multi-Wing IAQ Investigation
Building-wide IAQ investigation following persistent occupant complaints in two wings — root cause traced to HVAC condensate management.
Three-wing elementary campus, ~720 students. Persistent complaints of musty odors in Wings B and C.
HVAC system age ~14 years. Two condensate pump failures in the prior 18 months in Wing C.
Walkthrough, multi-parameter IAQ logging, HVAC plenum inspection, surface and air sampling.
Elevated relative humidity (>65%) in Wing C return plenums during cooling cycles.
Thermal imaging identified condensate accumulation in two AHU drain pans and insulation degradation downstream.
Air spore counts at registers vs. outdoor controls; surface sampling at AHU coils.
Coil surface samples confirmed Cladosporium and Aspergillus/Penicillium colonization consistent with chronic biofilm.
Source was HVAC microbial amplification distributing throughout Wings B/C via ductwork.
Coil and drain pan cleaning, condensate management redesign, in-duct UV consideration, post-remediation re-sampling.
NADCA ACR-compliant cleaning, AHU component replacement, and PRV via post-clean sampling.
A small, persistent HVAC failure can drive months of building-wide IAQ complaints. Root-cause investigation is faster than chasing individual rooms.