The Complaint That Wasn't About the AC

A Naperville office building had been fielding the same complaint from three different tenants over two weeks: "It's too hot on the third floor." Facilities checked the thermostat readings. Everything was within two degrees of setpoint. The AC wasn't broken.

What the readings didn't capture was the humidity. The third floor was running nearly 15% higher relative humidity than the rest of the building — enough to make 74°F feel closer to 80°F, and enough to leave the air feeling heavy and stale even when the temperature gauge looked fine.

The cause wasn't the cooling system at all. It was a return air filter overdue for replacement, restricting airflow and letting moisture build up faster than the system could pull it back out. A five-dollar filter and forty minutes of labor closed out three weeks of complaints.

Why this matters more in August than it did in June

1. Check humidity, not just temperature
A thermostat reading in range doesn’t always mean the space feels comfortable. Bring a humidity meter on your next walkthrough. High humidity can lead to complaints even when temperature setpoints are correct.

2. Check filters mid-cycle
Don’t wait for the quarterly filter change. Check filters halfway through the cycle, especially in high-traffic areas. If they’re already loaded, adjust the schedule based on usage and season.

3. Inspect exterior intake areas
HVAC issues can start outside. During maintenance walks, check intake louvers and vents and keep surrounding areas clear. Removing algae and buildup near HVAC equipment can help maintain proper airflow.

The properties that avoid a summer full of comfort complaints share a habit: they treat filtration and humidity control as a maintenance schedule, not a reaction to a tenant email.

That mindset extends to the exterior, too. A property with clean intake louvers, unobstructed exterior vents, and a facade free of biological buildup near HVAC equipment gives its systems a fairer chance to do their job. Starbucks, Cinemark, and other high-occupancy commercial spaces we service across DuPage County treat that exterior upkeep as part of the same operational discipline that keeps interior systems running clean — not a separate line item.

Q: "Our filters are on a quarterly replacement schedule. Is that enough in the summer?"

For a lot of properties, no — not without adjusting for the season.

A quarterly schedule is often built around average-case loading, but humid summer months push more particulate and moisture through a filter faster than a dry spring month does. High-occupancy zones, ground-floor retail with heavier foot traffic, and any space near an exterior door or loading area will load filters well ahead of a fixed quarterly timeline.

A better approach for peak summer is a visual check at the halfway point between scheduled replacements — pull the filter, hold it up to light, and see how much is actually getting through. If it's noticeably restricted before the quarter is up, that's your building telling you the schedule needs to flex with the season, not just the calendar.

Tenant comfort complaints in August are rarely about one broken thing. They're usually about several small things compounding — a filter running a few weeks past its ideal replacement point, humidity nobody's tracking separately from temperature, and exterior intake areas that haven't been looked at since spring.

We can't fix the filter or the humidistat. What we can do is make sure the exterior side of the equation isn't working against your HVAC system — clean intake louvers, clear vents, and facades free of the algae and buildup that restrict airflow before it ever reaches the building.

What we do:

Summer Commercial Offer
Free exterior property estimate — schedule this week to get ahead of any airflow-related maintenance before fall.

Know a property manager fielding "it's too hot" complaints that temperature readings can't explain? Forward them The Shiny Bubble — Commercial Edition.