Watch Your Indoor Humidity This Winter

We often associate humidity with summertime, when high humidity can make for seemingly suffocating conditions in the outdoors. But humidity is an important factor all year round, and in the winter, it’s the humidity inside your home that you need to be particularly mindful about.

It’s All Relative

When it comes to the humidity levels inside your home, it’s relative humidity that you should be concerned about, and that’s easy to measure accurately with a handheld hygrometer. Digital models are inexpensive and easy to find online or at hardware stores. There are also decorative and antique hygrometers that hang on the wall or sit on a desktop.

For health purposes, it’s optimal for indoor relative humidity to fall somewhere in the range of 40 to 60 percent. That will help you avoid the irritating physical symptoms associated with air that is too dry, while protecting you from the more dangerous health risks that come along with high indoor humidity.

But when winter temperatures descend on your home, it’s often important to favor the low end of the humidity spectrum, and some circumstances may force you to go far below 40 percent relative humidity for the sake of your home.

A Slippery Problem

Cold winter air is inherently dry, and no matter how well sealed your home is, the change in the season will cause your indoor humidity to drop. If your home is not well sealed, the cold air infiltrating your home could cause the indoor humidity to drop severely, leading to dry skin, eyes, throats and nasal passages, the buildup of static electricity and possibly even damage to wood furnishings.

But if you fight back against dry air by boosting the humidity in your home -- say, by turning on a humidifier -- you can create a new problem: condensation. You may see droplets form on the inside of your windows if your indoor humidity is too high for the outdoor temperatures. Sometimes the condensation will freeze on the glass in a sheet of ice. When the problem is severe, you may see condensation form on walls and ceilings. It’s also possible this is happening in unseen areas, such as your attic or inside your walls.

This kind of moisture buildup can rot wood and lead to the development of hazardous mold and mildew inside your home. If your home is well sealed and equipped with excellent insulation and windows, you’re less likely to develop this problem. But while improving your home insulation and envelope is always a good thing, the real solution to this problem is to track and manage your indoor relative humidity throughout the winter.

How Low Can You Go?

The colder it gets outside, the more your indoor humidity can lead to the development of condensation. According to guidelines from the Minnesota Department of Public Service, you should start managing indoor humidity below the 40 to 60 percent range once the outdoor temperature dips below 40 degrees Fahrenheit:

  • Maximum 40 percent indoor humidity when outdoor temperatures range from 20 to 40 degrees
  • Maximum 35 percent indoor humidity when outdoor temperatures range from 10 to 20 degrees
  • Maximum 30 percent indoor humidity when outdoor temperatures range from 0 to 10 degrees
  • Maximum 25 percent indoor humidity when outdoor temperatures range from -10 to 0 degrees
  • Maximum 20 percent indoor humidity when outdoor temperatures range from -20 to -10 degrees
  • Maximum 15 percent indoor humidity when outdoor temperatures are below -20 degrees

A diligent homeowner can keep indoor humidity at optimal wintertime levels by keeping an eye on the thermometer and hygrometer while not overusing humidifiers. But there are also more sophisticated solutions that utilize whole-home humidifiers and smart thermostats to manage these levels for you. To learn more, or for any humidity management or HVAC solutions, get in touch with your local One Hour Heating & Air Conditioning today.