Indoor humidity in winter is defined by the gap between outdoor and indoor temperatures. For example:
At +20 °C and 60% relative humidity → ~10 g/m³ absolute humidity
At –20 °C and 60% relative humidity → only ~0.5 g/m³
That means cold winter air contains ~20 times less moisture. Once warmed indoors, that air may drop indoor RH to as low as 3%.
Humidity recovery can only bring back the small portion of moisture that condenses in the exhaust air – not nearly enough to maintain comfort levels. As a result, well-ventilated homes often face dry indoor air in winter.
👉 The solution lies in demand-controlled ventilation:
Avoid over-ventilating empty rooms
Allow natural humidity generation indoors (each adult produces ~3 liters of water vapor daily through breathing, cooking, and washing).
By removing primarily CO₂ and pollutants — while keeping enough natural humidity indoors — demand-based ventilation ensures healthy and comfortable air quality at the lowest cost.
Demand-controlled ventilation is the smartest way to maintain optimal indoor climate in winter.