How Humid (or Dry) Should Your Home Be?


One key component of good ventilation is humidity control. Too much moisture in the air can cause condensation in the home, which can lead to respiratory symptoms, mold growth and even structural damage to the home.  

Cooking, showering, laundry and humidifiers all add moisture to the air, which condenses on cooler surfaces when the air becomes saturated. The average person contributes 1.25 liters of moisture to the air every day simply by breathing and perspiration! 

Air that’s too dry can lead to increased exposure to viruses and bacteria. While it’s less likely to cause structural damage, it can lead to shrinking and cracking of wood. 

Relative humidity is the amount of water vapor in the air compared to the total amount of vapor that the air can hold. The higher that number gets, the more uncomfortable the air feels. Optimum relative humidity in homes is between 40%-60%.  

An Enthalpy Recovery Ventilation (ERV) unit can help keep home humidity at this optimum level year round. By transferring moisture from the wetter air stream to the dryer airstream, Zehnder ERV systems help keep the relative humidity at a constant level for more comfortable, healthier living. 

However, in the summer, an ERV cannot completely dehumidify the air. ERVs remove moisture from the intake air and transfer it to the drier exhaust air, but they cannot remove all of the moisture from the air. While inside air with an ERV will be less humid than the outside air, it can still get to undesirable levels. Air conditioning may help dry out the air, if allowed to run long enough. Dehumidifiers, either portable or whole-home systems, can also help keep the indoor air at an optimal level.