It’s not just the heat—it’s the humidity.
We’ve all heard the phrase, but for facility managers, it’s a serious operational headache. High indoor humidity is the silent killer of commercial buildings. It makes tenants complain about being “clammy,” warps wood and drywall, and, most dangerously, creates the perfect breeding ground for mold.
As we head into the warmer months, controlling your building’s moisture levels is just as important as controlling the temperature. Here is what you need to know to keep your facility safe and comfortable.
The “Goldilocks Zone” for Buildings
ASHRAE (The American Society of Heating, Refrigerating and Air-Conditioning Engineers) recommends maintaining indoor Relative Humidity (RH) between 40% and 60%.
Below 40%: Air is too dry, leading to static electricity, dried-out wood, and respiratory irritation for occupants.
Above 60%: The danger zone. The air feels heavy, odors linger, and mold spores begin to colonize surfaces.
Why Your AC Might Be Failing at Dehumidification
Many building owners assume that if the AC is running, humidity is being handled. This is a myth. Standard commercial HVAC units are designed primarily to cool air, with dehumidification as a secondary benefit.
If your building feels cold but “sticky,” you might have one of these common issues:
1. Oversized HVAC Units (Short-Cycling) If your HVAC unit is too big for the space, it cools the room down incredibly fast and then shuts off. This is called “short-cycling.”
The Problem: The unit doesn’t run long enough to pull moisture out of the air. It satisfies the thermostat (temperature) but fails the hygrometer (humidity).
The Fix: A load calculation audit by Pronto MS to ensure your equipment matches your building’s actual needs.
2. Dirty Coils and Clogged Drains Your HVAC system removes humidity by passing warm air over cold evaporator coils. Condensation forms (like a cold glass on a hot day) and drains away.
The Problem: If coils are coated in dust or grime (a common post-winter issue), they can’t effectively transfer heat or condense water. If the condensate drain is clogged, that water stays in the system—or worse, leaks into your ceiling.
The Fix: Regular coil cleaning and condensate line inspections.
3. Poor Ventilation Control Bringing in fresh outdoor air is essential for CO2 levels, but bringing in humid outdoor air without treating it first is a recipe for disaster. Your Dedicated Outdoor Air Systems (DOAS) must be calibrated to remove moisture from intake air before it mixes with your indoor climate.
The Mold Connection: Preventing the Nightmare Scenario
Mold doesn’t need a leak to grow; it just needs high humidity and organic material (like drywall or dust). Once mold infiltrates your ductwork, remediation becomes expensive and disruptive.
Prevention is always cheaper than remediation. By keeping your RH below 60% through proper HVAC maintenance, you starve mold spores of the moisture they need to survive.
Your Humidity Control Checklist
Don’t wait for a tenant to complain about a musty smell. Take these steps now:
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Install Humidity Sensors: Don’t rely on the thermostat alone. Install independent hygrometers in problem areas.
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Check the P-Traps: Ensure HVAC condensate traps haven’t dried out, which can allow sewer gases or moisture back into the unit.
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Schedule a Preventive Maintenance Visit: Have a technician verify that your compressors are running at the correct pressures to maximize dehumidification.
Need Help Balancing Your Air?
At Pronto MS, we understand the science of comfortable buildings. From sizing units correctly to deep-cleaning coils for maximum efficiency, we help you maintain the perfect environment.
Contact Pronto MS Today to schedule an HVAC evaluation.
Protect your property. Protect your people.