Low-Cost Humidity Solutions in Occupied Buildings

Posted by Stuart Heisey on Thursday, June 30, 2022

Turning up your thermostadt's setpoint

Facing humidity issues in occupied buildings is typically more challenging than in unoccupied buildings, mainly because of those “pesky” occupants. Yeah, those people (who are likely paying your organization or being paid by your organization to be there) really make things more difficult! They are either too hot or too cold or don’t want to sit next to a massive fan or dehumidifier humming away at a cool 60 decibels. I mean, sheesh - the nerve of these folks, can’t they just be happy to be indoors?

In all seriousness, most building types are designed to be occupied and that does take away some of the quickest and easiest humidity control options, but all hope is not lost! Below I’ve compiled some low-cost options to combat humidity in occupied spaces, but if there are times when the building is unoccupied or has reduced occupancy (ie: at night, weekends, etc.) you can find more tips in our Preventing Humidity Issues in Vacant Buildings blog.

Ok, enough background, onto the solutions!

Occupied Building Low-Cost Humidity Solutions:

Solution Description High / Low Humidity Cost
Data Loggers Do you have high or low humidity or both? Is it a constant problem or just at specific times or on specific days? Dataloggers are an inexpensive way to get an accurate view of your building’s operation and understand the temperature, relative humidity, and dewpoint over a given time period. This is great information that will help you narrow in on likely causes and solutions. Both $$$$$
Low, typically under $100 each.
Close Windows & Doors In the summertime, open windows and doors lets humid air directly into your building. A quick sweep around the building will identify any culprits. Outside air is great for indoor air quality in general, but if it enters unconditioned it can be troublesome. High $$$$$
Very Low – a quick walkthrough each building
Envelope Maintenance Envelope maintenance is all about keeping the outside air and water outside and not coming unintentionally into your buildings. Checking and re-caulking around windows and doors, where necessary is important maintenance. Additionally, keeping gutters, downspouts, and drainage areas free of debris will move stormwaters where they belong – away from your building. Take a look at window and door seals also. Both $$$$$
Mid – Material cost low, but some labor here.
HVAC Maintenance HVAC equipment is rarely the cause of a humidity issue, but it can exacerbate the issue if it is not operating properly. Routine maintenance, such as cleaning coils, changing filters, etc. can get your system back into shape quickly. You can DIY or hire an HVAC contractor. Either way, someone who understands the system and can ensure it is operating as designed while performing maintenance is a win/win. Over time, occupants or owners may make a small change (ie: turning on/off a fan) that could have drastic unintended consequences. Both $$$$$
Mid – Material cost low, but labor potential here.
Raise the Temperature Setpoint Raise the temperature when it’s humid, what!?! Yup, that’s right. Relative humidity and temperature are inversely related. So, if you’re cooling is set at 70F degrees and relative humidity is high, lowing the temperature to say 68F will only increase the relative humidity. Instead, raise the temperature setpoint and the relative humidity will decrease. The optimal cooling season range is between 74-78F. Individual fans or ceiling fans will make this temperature range very comfortable. High $$$$$
Lower than low… This strategy will SAVE you money!
Add Reheat

Sometimes when ventilation air or certain activities are necessary in your building, added humidity is unavoidable. So, the only way to drive humidity from your spaces is to sub-cool the air without over-cooling the space. This means reheat is needed. The cheapest way to do this is space heaters but other forms of reheat might be available in your HVAC system.

Why does this work? During cooling, water vapor from the air will condense on the AC coils, essentially providing dehumidification. The problem in many systems is that the cooling is oversized and doesn’t need to operate long enough for this to provide sufficient dehumidification. Although far from optimal, it is relatively inexpensive to add heat back to the system/building to run the AC unit(s) long enough to dehumidify, without turning your occupants into popsicles. Again, extra energy is consumed in this strategy, but it is likely pennies on the dollar when compared to addressing the root humidity causes of building envelope and/or HVAC system replacement. There are more complex and energy-efficient methods for providing reheat, and these should be considered in any new system installation or system renewal.

High $$$$$
Low –Even the cost of electric reheat is low when compared to just about every other option on this list.

I think that pretty much covers all of the low-cost solutions, but please let me know in the comments below if you have other ideas! As I stated in the open, if you can find time where parts or all of your buildings are unoccupied, there are more low-cost solutions in my Preventing Humidity Issues in Vacant Buildings blog. You can also check out all of our building humidity blog topics.

Stuart Heisey, PE Photo

Stuart Heisey, PE


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Categories: Buildings & Campus

Tagged: Building Humidity

Add a Comment

I'm working on a project for school. Becoming a Building Operator. I'm working on some humidity stuff, and the articles you've written on this site are spectacular. Thank you for sharing your knowledge like this! Really helpful.
Posted by Scotty on Sunday, July 31, 2022, 12:36 PM

Thanks Scotty! Our pleasure, good luck with your project!
Posted by Stuart H. on Monday, August 1, 2022, 8:34 AM