There are 3 main components to good indoor air quality. Fresh air, clean air, and proper humidity which is what we will be focusing on. Humidity is the quantity of water vapor suspended in the air. Having proper humidity will inhibit the growth of mold, mildew, and bacteria in our home. It will also reduce the risk of respiratory tract infection and other diseases associated with the allergens. While we cannot change outdoor humidity, we will have our final say with indoor humidity.
What Is The Ideal Humidity In House?
50% would be a good indoor humidity level for a home in most situations. However, don't be too fixated with the numbers as they are many factors you would need to account for. From outdoor temperature, family's preferences, physical activities, climate/ seasons to health conditions all play their part. In general, anything that falls between the range of 30-50% relative humidity level is perfectly fine as recommended by Consumer Product Safety Commission. It will provide breathing comfort, relieve illnesses, protect wooden furniture, and prevent microorganism growth. To find out what is the humidity level in a home, you will need a hygrometer, which measures room temperature and relative humidity (RH).
What Is a Good Indoor Humidity In Winter?
For winter months, the ideal indoor humidity level would be between 30-40%. The reason we lower the recommended RH level to 10 percent is to avoid any condensation on the windows. As air is drier during winter, a humidifier can make a big difference in moisturizing the air.
What Is a Good Indoor Humidity In Summer?
For summer months, the ideal indoor humidity level would be between 30-60%. As air carries more moisture from the hot climate, a dehumidifier would make perfect sense to reduce dampness in a home. By increasing the RH level by 10 percent, it prevents the dehumidifier from overburden and a big surge on the electricity bill.
Ideal Indoor Humidity Level By Outdoor Temperature
The lower the outdoor temperature, the lower the indoor humidity level should be. This is according to the Minnesota Department of Public Service and many manufacturers’ manuals. Keep in mind that outside temperature is only one of the determining factors. You may also need to account for the number of windows, heating, and air conditioning in a home. The recommended indoor relative humidity level below will give a gauge of what needs to be set in a dehumidifier.
- If outdoor temperature is over 50˚F, indoor humidity level should not be more than 50%
- If outdoor temperature is over 20˚F, indoor humidity level should not be more than 40%
- If outdoor temperature is between 10˚F to 20˚F, indoor humidity level should not be more than 35%
- If outdoor temperature is between 0˚F to 10˚F, indoor humidity level should not be more than 30%
- If outdoor temperature is between -10˚F to 0˚F, indoor humidity level should not be more than 25%
- If outdoor temperature is between -20˚F to -10˚F, indoor humidity level should not be more than 20%
- If outdoor temperature is between -20˚F or lower, indoor humidity level should not be more than 15%
Ideal Indoor Humidity Chart
|Outside Temperature (°F)||Outside Temperature (°C)||Indoor Relative Humidity|
|+50˚F or higher||+10°C or higher||50%|
|+20˚F or higher||-7°C or higher||40%|
|+10˚F to +20˚F||-12°C to -7°C||35%|
|0˚F to +10˚F||-17°C to -12°C||30%|
|-10˚F to 0˚F||-23°C to -17°C||25%|
|-20˚F to -10˚F||-29°C to -23°C||20%|
|-20˚F or lower||-29°C or lower||15%|
Signs Of Excessive Indoor Humidity
Too much humidity will make you feel sick and uncomfortable all day long. This is because in a damp environment, the body cannot regulate its internal temperature through evaporation. Excessive moisture will also create a breeding ground for mold/ mildew, destroy your home structure and have an adverse effect on your health. In short, indoor humidity level above 60% is too high in a house so do look out for below signs and symptoms.
- Musty odor in your home, particularly in the basement, garage or crawlspace
- Visible mold growth in your home on wall, ceiling, tiles, and bathroom
- More pesticide and insects like dust mites, cockroaches popping up
- Water stains on wall and ceiling
- Visible condensation on windows
- Cupped wood floors
- Furniture started to crack, rot, swell and warp
- Peeling wallpaper or blistering “bubbles” paint
- Whole house feel warmer and stuffy despite at a normal room temperature
- Struggle to fall and stay asleep from excessive body heat
- Hot, sticky or muggy feeling at home
- Experiencing mold allergic reactions (Runny nose, red eyes, headache, itchy throat, postnasal cough)
- Fatigue from Heat exhaustion, dehydration
- Muscle cramp
- Breathing difficulties especially people with asthma and allergies
Signs Of Low Indoor Humidity
We are talking about Dry air with a humidity level below 30 percent. Too little humidity will also affect your breathing comfort and damage your home possessions. You will feel the chill even at higher temperature due to our body moisture evaporates quicker. Low humidity will lead to all kinds of irritation mainly on your nose, skin, and throat. Even though the impact is not as obvious as excessive humidity, there are some clear signs that you are treading on thin ice.
- Dry, flaky, and itchy skin
- Eczema, allergy, and asthma flare-ups
- Chapped and cracked lips
- Sore, scratchy throat (from dry out mucous membranes)
- Coughing, wheezing, and chest tightness
- Breathing difficulty
- Sleepless night from constant night cough and throat irritation
- Increase in static electricity
- Cracking, warping and shrinking dried wood e.g. door frames, cabinet, chairs, tables
- Creaking wooden floor
Maintaining Ideal Indoor Humidity In House
Managing indoor humidity should be the utmost priority for every homeowner. Here are some quick tips to maintain the indoor humidity level within 30-50%. For places with high humidity problems, avoid steam shower, boiling water, or drying clothes inside. Opt for a cold shower and dry your clothes outside instead. Open windows and doors if you’re not running on any air conditioner or ventilation. Otherwise, use air conditioner, exhaust ventilation fan to prevent air from being stagnant. Fix any leaky pipes, crack roof or clogged gutter. Caulk and seal windows and doors to prevent hot air from creeping out and cold air from infiltrating. Little things like charcoal briquettes, desiccants or moving your house plants away do help but at a minimum level.
For places with low humidity problems, just do the opposite of what we have alluded earlier. Feel free to boil water with stove, enjoy a hot shower and dry clothes indoor. Get more houseplants that will clean the air and provide moisture. This may sound weird, placing bowls of water at every corner does help bring room dampness up. Remember to inspect home ventilation, ductwork, and insulation for any leakage while you’re at it.
But none of the above methods is as effective as getting a humidifier or dehumidifier. It is without a shadow of a doubt the best tool to maintain ideal humidity in a house. A humidifier increases the dampness level in your home by dispersing moisture. Dehumidifier does the opposite by decreases the dampness level with moisture absorption. While both machines will work in conjunction with an air purifier, air conditioner, and heating system, there are some running costs on it. In the long run, it is definitely worth every penny you paid as it can save you from enduring countless home repair damage caused by rotting building material. More critically, you can never put a price on one’s health.