4/26/2014

Effects of Indoor Humidity

One of the functions of an energy recovery ventilator (ERV) is to lower the humidity entering the home in a hot, humid climate. To understand the true benefits of indoor humidity control, it is important to understand humidity and the effects it has on the body. Research shows that indoor humidity can contribute to illnesses and health conditions such as allergies and respiratory infections. It’s important to have a strategy to maintain comfortable and healthy humidity levels.

What Is Humidity?

By definition, humidity is the level of water vapor present in the air. Water vapor is the invisible, gaseous state of water. Humidity is measured in three ways: absolute, specific, and relative. When discussing indoor air humidity, relative humidity is the most common method of measurement. Relative humidity is given as a percentage that measures the air’s current water content in comparison to the highest level of water content possible for that temperature. For example, 50% relative humidity means that an area is half as humid as it could possibly be.

Recommended Relative Humidity

The recommended percentage of indoor humidity in homes and buildings is debated. A number of experts and organizations such as the Environmental Protection Agency (EPA) recommend that indoor relative humidity remains between 30% and 50%, depending on the climate of the area. A relative humidity that exceeds 60% is significantly more likely to have negative effects on the health of a home’s inhabitants.

Dangers of Indoor Humidity

Studies show that indoor humidity that is too high or too low can create health problems for individuals. Indoor humidity that is too low can contribute to issues like dry skin, chapped lips, and sore throats. This is because low humidity leads to dry air. Additionally, low humidity may cause indoor areas to feel colder than the actual temperature. Conversely, high humidity leads to air that is too moist. High indoor humidity allows for the increased growth of air pathogens like mold, fungus, dust mites, and bacteria.

Humidity and Air Pathogens

A home with high humidity will often contain higher levels of air pathogens like mold. Mold can cause serious complications, such as asthma, allergic reactions, and respiratory infections. Studies show that these pathogens flourish in homes and buildings with high humidity, especially relative humidity levels above 70%. In a high-performance building, energy recovery ventilators help maintain healthy and comfortable indoor humidity levels by reducing the humidity of incoming air during the hot, humid summertime.