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Hygrothermal Dynamics: Understanding the Basics Can Protect Your People, Buildings and Business

An illustration describing how thermodynamics works to help buildings breatheUnless your career is based in science or you deal with metal building ventilation daily, like us, chances are you haven’t put much thought into hygrothermal dynamics since high school physics. If you know Metallic Products, though, you know we’re big believers in the idea that having a general grasp of the tools and principles that impact your company’s operations is a good thing.

For that reason, we decided it was time to go back to basics as it relates to hygrothermal dynamics. Join us as we cover need-to-know info about the science itself — and discuss ways you can use it to make your steel buildings’ indoor environments healthier, protect your business and look out for your bottom line.


What is Hygrothermal Dynamics?
First things first: Let’s break down the phrase itself. Here, “hygro” refers to water, while “thermal” refers to heat. So, hygrothermal dynamics centers on the combination of moisture and heat — specifically how it moves through a building.

There are a few key principles that really drive the study of hygrothermal dynamics:

  • Warm Air Rises: This is due to the fact that warmer air is less dense. Cooler, heavier air, meanwhile, sinks as gravity pulls down on it. (This is the guiding force behind how a hot air balloon operates.)
  • Condensation Forms When Vapor in Warm Air Encounters a Cool Surface: You see this a lot on entryway doors, where hot outer temperatures meet cooler indoor climates. But no solid surface is required for this to happen. The effect can take place when a warm pocket of water vapor comes in contact with cooler gases.
  • Low Pressure Air Joins with Higher Pressure Air, Creating Lift: As it relates to your steel buildings, lower pressure air above your ridge vent meets with higher pressure air inside, moving warm, stale air out. (This is the same concept that helps explain how an airplane wing works.)

Why should these points matter to you?

Put simply, it’s impossible to manage a building’s temperature without also managing its moisture levels. And elevated humidity can have impacts far beyond simply making interiors uncomfortable. Left unchecked, it can lead to mold and mildew formation that aggravate allergies and create unhealthy environments. Not only that, but it can result in structural damage that costs you out of pocket.

So, by structuring your metal building’s ventilation system with hygrothermal dynamics in mind from the start, you can help ward of costly replacement work while creating a healthier overall working environment.


What Role Do Your Metal Building Accessories Play in Creating Healthy Structures?
As any builder knows, it takes countless systems, accessories and elements coming together in just the right way to ensure a successful metal building project. And, while your ventilation accessories are just part of that puzzle, they’re a pretty important part.

Each ventilation accessory is engineered to carry out a particular job — from the power vents controlled via thermostat, to the wind-powered turbine vents which help remove heat, fumes and stale air. The key is to have every element in its proper place, in proper working order.

Our go-to example involves the ridge vent that sits at your roof’s peak. As lower-pressure wind blows over your steel building’s ridge vent, higher-pressure air inside your building is ushered up and out. This is helped along by inlets such as strategically located wall louvers which allow the proper amount of air in to begin with.

When installed properly and adequately maintained, your metal building accessories should provide ventilation benefits for a long (long) time, with little to no additional work on your part.


Hygrothermal Dynamics Issues Metal Buildings Regularly Experience
No construction project (metal building or otherwise) ever goes exactly to plan, but we see countless issues come into play that could have been avoided, had companies put in a bit of forethought.

Failing to take airflow into consideration at the start of a build (something that happens more frequently than you might think the metal building world) can lead to uncomfortable — oftentimes unhealthy — indoor conditions. Here are a few common issues we regularly encounter in the field:

  • Competition Between Powered and Natural Ventilation: Remember, too much of a good thing isn’t a good thing. Although most industrial operations feature ventilation systems that have a mix of powered and unpowered elements, the system has to come together in a way that keeps everything working in tandem. Operations that go all in on natural ventilation accessories such as ridge vents and louvers, as well as full-scale HVAC air management systems (without adequate planning) can find themselves in a situation where one system is negating the efforts of the other.
  •  Large Fans Placed Below Ridge Vents: When a company finds its indoor environments are running too warm, the solution is often to buy an oversized ceiling fan, install it in the warehouse and wait to reap the airflow benefits. Unfortunately, that doesn’t always work. This is because the ridge vent atop your building does a lot of heavy lifting, helping to move warm, stale air. By installing your fan in close proximity, you throw the system off and lessen the effects of both the fan and your ridge vent.
  • Negative Air Pressure Inside a Structure: Certain production and manufacturing processes — such as machinery that pushes too much air out of your building — can result in an overabundance of negative air pressure. When this happens, warm, humid or contaminated air has a tendency to become trapped inside.
  • Mold and Mildew Buildup Due to Overabundant Insulation: In an effort to sidestep air leakage which can run up energy bills and lead to structural damage, it’s become common for metal building companies to install increasingly thicker insulation. The problem is, adequate airflow plays an important role in controlling condensation and helping your buildings breathe. By stuffing too much material into your steel building’s wall or roof, air can no longer circulate. Thus, moisture becomes trapped, builds up and leads to all sorts of undesirable issues.

How can you ward off such issues and help keep your metal buildings on better footing overall? Enlist help from a trained and licensed ventilation professional when you start planning your structure out. They’ll be able to help guide your planning and design processes in a way that ensures a quality design and optimum airflow. (And it’s a lot less expensive and stressful than having to go back to fix mistakes after the fact.)


We hope this overview helped to shed a bit of light on the concept of hygrothermal dynamics, and provided tips to help you embark on your next metal building project better prepared. If you have questions about any of the above, or if you’re interested in learning how Metallic Products’ building accessories might benefit your next project, feel free to reach out to our team. We’re here, and we’re happy to help.