By mid-July, the air across Durham Region can feel as heavy indoors as it does outside. When a home holds too much moisture, it feels warmer than the thermostat says, the air turns sticky, and over time you risk condensation, musty smells, and mould. Good indoor humidity control summer after summer is one of the most underrated parts of staying comfortable in an Ontario home, and it is closely tied to how well your cooling system is working.
Here is how we think about humidity with our customers, and the practical steps that make the biggest difference.
What “Comfortable” Humidity Actually Means
Indoor relative humidity in the range of roughly 40 to 50 percent is the sweet spot for most homes in summer. Below that, things can feel dry; push well above it and the home starts to feel clammy, surfaces sweat, and the conditions that allow mould to grow take hold. A simple inexpensive hygrometer lets you see where your home actually sits, which is the first step before changing anything.
Health and building-science authorities such as the EPA’s guidance on mould and moisture consistently point to controlling indoor moisture as the single most effective way to prevent mould — you are not just chasing comfort, you are protecting the house.
Your Air Conditioner Is Also a Dehumidifier
This surprises a lot of people. As warm indoor air passes over the cold evaporator coil, moisture condenses out and drains away. That means a properly working, properly sized air conditioner removes a meaningful amount of humidity as a side effect of cooling.
It also explains why an oversized AC can leave a house feeling damp: it cools the air so fast that it shuts off before it has run long enough to wring out much moisture. If your home feels cool but clammy, sizing or short cycling may be the real culprit, not the humidity itself.
Signs Your Home Is Holding Too Much Moisture
Watch for foggy or sweating windows, a musty smell that lingers in the basement, air that feels heavy even when the temperature is fine, and any black speckling around tubs, sills, or cool corners. Any of these means it is time to act before a comfort issue becomes a repair issue.
Practical Ways to Bring Humidity Down
Set the fan to auto. As with cooling efficiency, running the blower continuously can re-evaporate moisture off the coil back into your rooms. Auto lets that water drain away instead.
Make sure the AC is sized and serviced correctly. A right-sized, well-maintained system does most of the dehumidifying work for you. Annual HVAC maintenance keeps the coil clean and the drain clear so that moisture removal keeps working.
Add a dehumidifier where needed. Basements and below-grade spaces often need extra help. A portable unit handles one room; a whole-home dehumidifier tied into your ductwork manages the entire house and is worth considering in homes that struggle every summer.
Ventilate moisture at the source. Run bathroom and kitchen exhaust fans during and after showers and cooking, and make sure they vent outside rather than into an attic.
When to Call Our Team
If your home stays sticky despite a working air conditioner, if you are seeing condensation or mould, or if certain rooms never seem to dry out, give us a call. We can check whether your air conditioning is sized and operating correctly and recommend the right dehumidification approach for your specific home rather than a one-size-fits-all fix.
Where Summer Moisture Actually Comes From
Some of the humidity in your home rides in on the outdoor air every time a door opens, but a surprising amount is generated inside. Cooking, showering, dishwashing, laundry, and even houseplants and breathing all add moisture to the air. In a tightly built modern home that holds heat well, that internally generated moisture has fewer places to escape, so it accumulates. Understanding this is useful because it means humidity control is partly about removing moisture and partly about not creating more of it than you have to during the muggiest stretches.
Portable vs. Whole-Home Dehumidifiers
A portable dehumidifier is inexpensive and effective for a single problem area like a basement, but it has limits: you have to empty the reservoir or manage a drain hose, it adds a little heat and noise to the room, and it does nothing for the rest of the house. A whole-home dehumidifier installs alongside your existing system and conditions the entire home automatically, draining on its own and running quietly in the background. For a home that battles dampness every single summer — especially one with a finished basement — the whole-home option usually earns its keep in both comfort and protection against moisture damage.
How Humidity Changes the Temperature You Feel
The reason humidity control saves money is the same reason it improves comfort: damp air feels warmer than dry air at the same temperature, because your body cannot shed heat through evaporation as easily. Bring the moisture down and the very same 24 degrees suddenly feels pleasant, which means you can raise the thermostat a degree or two without losing any comfort. That is energy saved as a direct result of managing humidity — comfort and efficiency moving in the same direction for once.
A Few Habits That Help
Small routines add up: keep bathroom and range fans running a few minutes after showers and cooking, cover pots while they simmer, vent your dryer outdoors, and avoid drying laundry indoors during humid spells. None of these replaces a properly working system, but together they reduce the moisture load your equipment has to remove, which lets everything else work better.
Frequently Asked Questions
What indoor humidity level should I aim for in summer?
Roughly 40 to 50 percent relative humidity is comfortable for most homes and helps discourage mould. A small hygrometer makes it easy to monitor.
Why does my house feel humid even with the AC running?
Often the system is oversized or short cycling, so it cools quickly without running long enough to remove moisture. Running the fan on auto and confirming correct sizing usually helps.
Do I need a whole-home dehumidifier?
Not always. Many homes do fine with a correctly sized AC and a portable unit in problem areas, but homes that struggle every summer often benefit from a whole-home dehumidifier tied into the ductwork.
Will running my air conditioner more lower the humidity?
Up to a point, yes — the air conditioner removes moisture as it cools, so more runtime generally means drier air. But if the system is oversized it may cool the air quickly without running long enough to dehumidify, leaving you cold and still damp. In that situation, simply lowering the thermostat does not help and can waste energy. Correct sizing, keeping the fan on auto, and adding a dehumidifier where needed are usually far more effective than asking the AC to run harder.
Talk With Fortis Heating & Air Conditioning
If you are in Oshawa, Whitby, Ajax, Clarington, or anywhere across Durham Region and something about your cooling system does not feel right, we are happy to take a look. Call (289) 688-4822 or reach us through our contact page, and our team will help you sort out the next step at a pace that makes sense for your home.
