Does Air Conditioning Prevent Mold Growth?

Posted in Mold, on August 15, 2018

Air conditioning our homes does a lot of different things beyond making our homes more comfortable on hot days because air conditioning prevents mold growth too. This is one of the littler known facts about what an air conditioner’s job is in our homes, and during the worst of a humid Toronto summer, running your air conditioner can have a positive effect on your indoor environment in so many ways.

Because air conditioning prevents mold growth it’s a great tool to help combat the excessive amounts of humidity that summer living brings. Wet towels, bathing suits, indoor cooking, and bathing can all contribute to added humidity in the home, and big thunder and rainstorms add a lot outdoors. Whether or not you’re intending to, air conditioning prevents mold growth indoors, and it can be a big help in reducing that extra indoor moisture.

Prevent Mold Growth Indoors

Mold grows indoors for a number of reasons. First, our homes are made up of organic materials that would normally be growing in the wild - wood and wood products, for example. Secondly, our homes often prevent fresh air from reaching all spots, and motionless spaces that collect humidity are prime locations for mold to begin growing. The magical ingredient for mold growth is moisture, and warm air is one of the ways water can move around your home.

Trapped humid air can begin to help spawn a mold colony in two ways - it can condense onto a colder surface (think of cold water poured into a room temperature glass) or it can be absorbed into another material. However it travels, mold is an unwanted and dangerous thing to have growing in your home. Prevention is, as they say, nine tenths of the cure, and with mold this is equally as true.

Some ways to prevent mold are:

Identify leaks: Because mold prefers damp and humid spaces, one way to prevent those from forming is to watch out for leaks and ensure any you find are promptly fixed. Letting water leaks go unchecked can cause serious damage, in part because water flows through things and can cause mold under carpets, behind baseboards, and in walls and ceilings. Fixing a leak is much easier than repairing water damage or remediating mold - so setting aside time to have a leak solved is well worth it!
Air flow: Stagnant air is another reason that mold may grow in your home and another positive effect of air conditioner use. As it moves past a wet spot, fresh air helps to lift and remove moisture from a surface or area. Air conditioning prevents mold growth by moving cool air around the home and capturing humidity.
Monitor your humidity: Keeping an eye out for what’s happening in your home is the best way to head off any problems that may be forming. You generally want to look for a humidity reading of around 50% for a home in the summer - anything higher and you may be inviting trouble.
Run your air conditioner! This tip might be obvious - but it’s truly the most important weapon your have during the summer months to prevent mold growth in your home. Air conditioning prevents mold growth by helping dehumidify rooms and keep the air moving.

Can your air conditioner grow or kill mold?

Your air conditioner, like any other major appliance in your home, needs regular maintenance in order to run effectively and efficiently. Two persistent myths that we come across are that your air conditioning unit can kill or grow mold.

As far as killing mold goes, your air conditioner can’t help with that. It certainly helps to prevent mold, but once there’s mold in your home or in the HVAC system, it’s there until you take proper action to remove it. Mold can grow inside air conditioners, ducts, and other parts of your HVAC system too, which means that the mold spores have a direct route into each room of your home.

Regular maintenance of your air conditioning unit is key to keep it running smoothly and to prevent mold from growing in it - or around it. Make sure that no vegetation or garbage is piled around it, and ensure drain pipes aren’t blocked or stopped.

Why should I be preventing mold?

Your health and wellness is the first and foremost reason that mold growth in your home should be taken seriously. Mold reproduces by making spores, small airborne particles that are easily inhaled by the human body. Once in the body, mold spores can cause anything from mild to serious health issues, such as:

itchy, watery eyes
running nose
headache
congestion
increased respiratory illness
increased asthma attacks

While some types of mold may cause symptoms no more serious than that of the common cold or flu, other types - such as stachybotrys chartarum, or black mold - may cause life threatening health problems, or even death.

Frequently Asked Questions

What Prevents Mold?

While air conditioning prevents mold growth, it’s best used together with a number of other strategies to help prevent unwanted moisture. Simple habit shifts like running exhaust fans when you’re cooking or bathing can move hot air out of your indoor environment, as is drying out wet areas as soon as they’re spotted - clean up spills, bring in a fan to help dry really wet areas, and don’t let wet textiles linger.

Mold can’t grow without a source of moisture present, so its really important to make sure that any leaks or persistent drips are cleaned up promptly. Watch problem areas during wet weather or after particularly strong storms or the spring thaw. Pay close attention to the attic and basement, which can be particularly troublesome areas in many homes. If you notice a damp area, a little extra ventilation, whether from a fan or an open window, may help.

If you’re on track to do a renovation of any type, do some research or ask your contractor about what kind of mold resistant products they can use. Products like mold resistant gypsum or paint can give you more time to solve a moisture problem.

What is the best humidity level to prevent mold?

Humidity is one of the most important factors a homeowner should take into consideration when thinking about their indoor comfort. While temperature gets all the attention, humidity can have a greater effect on your health and day to day life. For example, think about a hot summer day: which is more preferable, a hot and humid one, or a hot and dry one?

Humidity is important when it comes to mold growth in your home as well. Cold air holds less moisture than warm air, which is in part why air conditioning prevents mold growth. A hot, humid house means that there’s lots of vaporized water particles in the air, and airborne water can move around in ways that liquid or solid water cannot.

To keep indoor moisture under control, we usually recommend a indoor humidity of 50%. There are inexpensive humidity monitoring devices on the market that can help you identify when your humidity might be too high - if you notice there’s an ongoing problem with high humidity, it’s important to figure out why and take measures to solve the problem.