How Home Humidity Is Tied to Indoor Air Quality and What You Can Do About It

Published on: February 21, 2015
Hygrometer and thermostat | AC Southeast®

Controlling home humidity is a constant battle in the southeastern United States, especially during periods of extreme heat or cold. Humidity is a key factor in overall indoor air quality, so it’s not something that you can simply ignore. Understanding how humidity affects your home and what the desired humidity levels are for each season can significantly increase home health, comfort and efficiency.

Winter Humidity Problems

During the winter, you’ll most likely keep doors and windows closed, re-circulating the same air over and over again throughout the day. Good weatherization practices seal air leaks, reducing the chance of normalizing the humidity through natural air exchange. As forced air heat runs, it significantly dries out the circulating air.

On the flip side, cold winter days make people more likely to take long, hot showers. It’s a great time to catch up on essential indoor activities such as cooking, laundry and washing dishes. All of these can produce high levels of humidity that, in the absence of a good exhaust fan, builds up inside your house without much chance of escaping to the outside air.

High humidity indoors during the winter leaves your home susceptible to condensation, particularly on the inside of windows and in unheated attic spaces. This moisture can cause significant damage to the wood and paint around the affected areas.

Low humidity leaves you feeling cold as the ambient air quickly wicks away moisture from your skin. If the air gets dry enough, it can also make your throat and nasal passages feel uncomfortably dry and sore.

Humidity in Summer Months

In most areas, summer days are either hot and heavy, or hot and extremely dry. It’s also a time when air conditioners run, potentially increasing indoor humidity. Doors or windows are often open to allow fresh breezes to flow through the house, bringing with them current outdoor humidity levels.

Warm, moist air and the dark recesses of your home are an awesome mix if you’re a mold spore. Summer moisture creates the perfect breeding ground for mold, mildew and all manner of other bacteria and fungi that may drift through the window. High humidity leads to condensation on the air conditioner, potentially corroding the coils.

Bear in mind, you feel warmer when the humidity is high. This can be a great advantage in the winter but a killer in the summer. You may crank up the air conditioner and live under the ceiling fan, but it’s not going to do much good unless you can lower the relative humidity.

Monitoring Indoor Humidity

The easiest way to track humidity levels inside your home is to set up a hygrometer or weather station. A hygrometer tracks the relative humidity inside the house. Weather stations show the relative humidity, current temperature, barometric pressure and other pieces of pertinent information. An outdoor weather station, or those with an outdoor component, may also track wind direction and speed. These help you understand what weather can do to your indoor humidity and whether you need to take steps to correct the levels.

Correcting Home Humidity Levels

In general, home humidity levels should be between 30 percent and 55 percent to maintain optimal comfort. Because the weather outside changes constantly, it’s a good idea to get into the habit of checking the indoor relative humidity regularly to know which control measures to take.

Consider investing in an electric humidifier or vaporizer to add humidity. If you have forced-air heat, you can buy an in-line humidifier that puts moisture directly back into the moving air as you condition the air in your home. Alternatively, a teapot or open pan of water on a fireplace or other heat source releases a steady stream of moisture in the form of steam.

Investing in an air conditioner with a dehumidifier is an excellent way to reduce humidity in the summer. When extra humidity strikes in the winter, consider a standalone dehumidifier with adjustable settings.

Both humidifiers and dehumidifiers must be sized correctly for your home. Discuss your home and humidity issues – with the average indoor relative humidity, if you know it – with a qualified HVAC technician for help choosing the right systems. Opt for Energy Star certified units for efficient, relatively low-cost operation for the life of the unit.

For help finding a contractor in your area who can help assess and control home humidity, contact us at AirConditioningSouthEast.com.