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How To Control Your Indoor Relative Humidity This Fall

Maintaining good indoor relative humidity levels can prevent many issues in your home. Learn how humidity control can help this fall.
Last Updated on August 18, 2021

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Almost half of U.S. homes have mold problems or excessive dampness. That’s a staggering amount of people impacted by poor humidity control. According to the study, researchers also noted how many health problems are caused or worsened by humidity extremes. They attributed one in five cases of asthma to indoor mold. Excessive dampness and dryness can be a problem in all indoor spaces–homes, businesses, schools, offices and the like. However, as homeowners or business owners, you can control the indoor relative humidity in the spaces you live and work in on a daily basis.

The fall season, and the cooler weather it brings, is often a time that highlights poor indoor relative humidity. With cooler autumn temperatures, we notice a drop in humidity levels as well. This is why it’s essential to monitor your home or indoor space’s relative humidity levels and pursue humidity control options. This way, you can keep levels from either dropping too low or rising too high.

What Is Indoor Relative Humidity?

Humidity is the concentration of water vapor in the air. There are two ways to measure it. One is absolute humidity, which is the water or moisture content of air at any temperature. The other is relative humidity, which is the amount of water vapor in the air compared to the maximum possible amount of water vapor. 

Indoor relative humidity, therefore, is a measurement of relative humidity levels inside a building. Relative humidity (RH) is described in percentages, and the ideal range for indoor spaces is between 40 to 60%.

What Is the Average Residential Indoor RH Level?

One study found that the average indoor relative humidity across various climates of the United States ranged from 47.9 to 53.1%. While the annual averages are within the ideal range, a breakdown of each region by month shows patterns dipping below or above the ideal range depending on the season. Additionally, homes in the cold northeast zone were those that registered the lowest RH levels, and those in the northwest marine region had the highest RH levels.

What Causes Lower Relative Humidity in the Fall?

As fall brings cooler temperatures, it also marks the start of using heat instead of AC. Additionally, homes with lower humidity levels often turn to space heaters or portable heaters to help warm their spaces. All of this contributes to drier fall and winter air indoors. This is because, though necessary for comfort, heaters can reduce indoor relative humidity. Also, cooler temperatures mean more time spent indoors and an end to open windows, which provides fresh air ventilation and natural humidity. All of these factors contribute to lower humidity levels in your living spaces.

Though low indoor relative humidity due to heater use may be more obvious in colder winter climates, the effects are still noticeable in temperate areas as well. While locales like Southern California won’t experience months of snow and freezing temperatures such as a state like New Hampshire would, the impact of running the heat is still noticeable.

Why Indoor Relative Humidity Matters and How It Impacts Your Space

The general rule to remember when it comes to indoor humidity is that mid-range is best. You want to avoid the extremes, which can cause both health and home quality issues. Low indoor relative humidity is the focal concern during the fall and winter months, however high indoor relative humidity can be just as damaging. It is a year-round problem that requires long-term solutions. Here are a couple of ways humidity problems during the autumn climate can exacerbate your health and home.

Health Concerns

Dry air can cause and worsen many health issues. According to researchers, dry air may promote lung issues such as COPD, asthma, influenza and other respiratory concerns. Poor indoor air quality caused by low relative humidity can also trigger more allergy attacks. This is because dry air allows particles, including allergens like mold spores and dust mites, to mix and circulate through the air easier. 

Many studies have found that humidity levels affect the survival rate of airborne pathogens. Moreover, indoor relative humidity seems to influence the infectivity of harmful microorganisms. Now more than ever, ensuring ideal humidity levels indoors is a crucial health investment. 

Dry air is also what causes the more common winter ails, like dry skin and chapped lips. The lack of moisture in the air can also worsen cold and flu season or even make you more vulnerable to illness due to drier sinuses.

Possible Damage in Your Home

Materials like wood floors and wood furnishings in your home are extremely susceptible to damage caused by dry indoor air. This could be cracks in flooring, trim or even window panes. Poor humidity control can also cause problems for your home’s walls, paint and wallpaper. Low humidity levels can even impact musical instruments, considering a fair amount are made of wood or have wood parts. This will eventually cause your instruments to sound out-of-tune. Books are also vulnerable to humidity extremes and will wrinkle without proper humidity control. It’s easy to assume that changes in your home’s surface and valuables simply happen over time, but it’s important to remember that there are HVAC solutions that can help prevent long-term damage.

Keeping Things Balanced

Humidity control is necessary to achieve comfortable indoor humidity. The first step is to measure the relative humidity of your space. IAQ experts can do this or you can do it on your own with a hygrometer. It’s a device that monitors indoor humidity and temperature.  

There are also central air monitoring systems that inform, in real-time, about numerous aspects of your indoor air quality. It installs directly into the duct system in your home and sends data to your phone—including crucial humidity information and levels. With accurate measurements and an idea of the average humidity in your home, a monitor can help you better determine the best whole-home humidity control solutions. 

Heading into autumn and winter, the next step will likely be to install a humidifier system to help regulate humidity. We recommend choosing whole-home humidifiers rather than portable units. Whole-home systems will do a better job at ensuring ideal indoor relative humidity levels throughout the entire home, while standalone units can only humidify small spaces at once. Some of the best whole-home humidifying systems are:

Steam Humidifiers

A steam humidifier monitors indoor relative humidity via a humidistat. This device looks like a thermostat, except it measures water content present in the air. When it detects low relative humidity levels, it sends a signal to the steam humidifier.

The humidifier then pumps moisture into the air by releasing steam. Your home heater, most likely a furnace or blower, then helps circulate the steam throughout your home, increasing the humidity level.

Evaporative Humidifiers

Evaporative humidifiers utilize an internal fan to draw air into the system, where it passes through a moisture-saturated wick filter. The filter itself gathers water from an internal reservoir in the humidifying unit. After the air passes through the saturated filter, it flows out into the room. It repeats this process until your home reaches the desired indoor relative humidity level. 

It’s also important to note that the filter must be kept clean. Similar to air filters, these filters must be checked regularly to ensure efficiency and healthy indoor air.

Whole-Home Humidifier: Looking for more information about whole-home humidity control soltuons? Check out our recent guide on steam and evaporative humidifiers. Read more ⟶

Proper Humidity Control

Choosing to invest in a whole-home humidifier will make your home or indoor space safer and healthier for all occupants during the fall and winter seasons when low indoor relative humidity levels are common. It will also help preserve your home and the materials and valuables inside. As we head into the fall season, now is the perfect time to make IAQ upgrades and protect the indoor areas you’ll spend most of your time in the upcoming months.

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