Dry winter air: bring humidity back to the right level, without fog or waste. Commercial humidification in Montréal, Laval, Longueuil, the South Shore and the North Shore
At −10 °C outside, fresh air warmed to 21 °C drops below 10% humidity. See where your space stands, then what each technology costs to bring it back up.
What winter does to the air in your space.
Set the weather and your target. The gauge shows fresh-air humidity once warmed, and the dew point tells you when windows will fog.
Outside, inside, your target
outdoor air warmed up, no water added
Magnus formula, standard atmospheric pressure. Order of magnitude.
Every litre of water added has a price. Here it is.
Enter your ventilation’s fresh air, your target and your hours. We calculate the water to add and the energy to evaporate it, with electric steam or adiabatic.
Your building
The starting values are an example. Replace them with yours.
before taxes, order of magnitude
Three ways to add water to the air.
Electrodes or heating elements. Precise control, air not cooled, highest consumption.
15.8 · 16Wetted media or atomization. Little electricity, but the air cools: heating makes up for it.
15.8 · 16For large loads. The gas connection is made by a partner.
Partner 15.2Where dry air costs comfort, products or equipment.
Dry eyes, sore throats and staff complaints all winter.
Dry paper curls, sticks and jams machines.
Wood that dries out cracks and warps.
Static electricity damages sensitive components.
Artworks and documents like stable humidity.
More fresh air in winter means more dry air to correct.
The legal minimum, the health target and the upper limit.
Tap a card for details.
From readings to start-up.
Humidity during business hours and a survey of the planned fresh air.
Steam, adiabatic or gas, based on your costs and space.
With what goes to the partner plumber or gas fitter.
Unit, duct distributor, wiring and sensors.
Target adjusted to the cold, maintenance added to the calendar.
The unit is ours, water and gas go to a partner.
Ducts, grilles, diffusers, air exchangers, make-up air, duct-mounted humidifiers.
Heat pumps, air conditioning, VRF, walk-in coolers, refrigerant piping.
Equipment power, controls, thermostats, sensor wiring (CMEQ).
- Water supply and building drain connection15.5
- Gas connection of a gas-fired humidifier15.2
AirGreen holds RBQ licence 5645-9605-01, subclasses 15.8, 15.10 and 16. Anything outside those subclasses goes to a partner who holds the right licence, and we tell you before you sign.
What makes a humidification project fail.
At −25 °C, the same target wets the windows.
Scale clogs the cylinder and the unit stops.
A steam humidifier drains hot water: it needs a planned drain.
Near a door or a register, it reads wrong.
Without a duct sensor, water can settle in the ductwork.
Too small, it cannot keep up. Too big, it wets the duct.
What people ask us about humidification.
Is there a mandatory minimum humidity at work?+
Yes. The RSST (s. 119) requires at least 20% relative humidity during working hours in offices and commercial establishments built or put into operation after December 19, 1979.
What level should we aim for?+
Health Canada recommends 30 to 50%. In deep cold, the low end of the range is often the target to avoid fog on windows. The psychrometer in section 01 shows your target’s dew point.
Why is the air so dry in winter?+
Cold air holds very little water. Once warmed to 21 °C, the same amount of water gives a very low relative humidity. The more fresh air you bring in, the more you need to add.
Electric steam or adiabatic?+
Electric steam is easy to control and does not cool the air, but it uses the most electricity. Adiabatic uses little electricity, but the water evaporates using the air’s heat, which the heating must replace. The calculator compares both.
Can we humidify with a gas unit?+
Yes, they exist. The gas connection is made by a partner holding subclass 15.2.
Do we need a plumber?+
Often for the water supply and the building drain connection. Those connections are made by a licensed plumber (15.5). The unit, its duct installation and its wiring stay with us.
Is too much humidity a risk?+
Yes: fog and frost on windows, condensation in walls, mould. That is why the target is set according to outdoor temperature and a high-limit sensor is kept in the duct.
What maintenance does a humidifier need?+
Scale is the enemy: cylinder or electrodes to replace, media to clean, drain and valve to check. We add it to your maintenance calendar before each winter.
And in summer, when it is too humid?+
That is the reverse: you need to dehumidify. See the commercial dehumidification page.
Are the calculator numbers exact?+
They are orders of magnitude: Magnus formula for humidity, indoors at 21 °C, Hydro-Québec rates of April 1, 2026. The real numbers come from a visit, your fresh-air flows and your bills.
No question matches. Call us at 514 316-2973, we will answer.
Your need often touches a neighbouring service.
The services most often combined with this one, plus the full needs search.
We measure your air, then propose the technology that costs least to run.
Free on-site estimate across Greater Montréal. Quote in 24 h, final price confirmed before work. See also our humidifiers.
Sources checked on November 2, 2026.
- Regulation respecting occupational health and safety (CQLR, c. S-2.1, r. 13), s. 119, LégisQuébec.
- Health Canada, Indoor air quality guidance: relative humidity of 30 to 50%.
- ANSI/ASHRAE Standard 62.1, Ventilation and Acceptable Indoor Air Quality: maximum dew point of 15 °C.
- Magnus formula (coefficients 17.62 and 243.12 °C), WMO, Guide to Instruments and Methods of Observation.
- Hydro-Québec, Electricity rates in effect April 1, 2026: rates G and M.
Amounts shown are indicative estimates, before taxes. Only Hydro-Québec, Énergir and the responsible bodies confirm a rate or an approved incentive.