Water from the tap, indoor temperature, heating, your car, even food in a restaurant—everything we consume is demand-based. It would be hard to imagine building a house, installing the plumbing, and then leaving out the faucets. Let the water just run all the time. Convenient when needed—no need to “turn the tap.”
Yet there is one thing that surrounds us everywhere and constantly flows through ducts. If there isn’t enough, we open a window. And even when it isn’t needed at all, it still keeps flowing. Ventilation is generally static almost everywhere. Designed once with fixed airflow rates, regardless of whether the room is empty or has 100 people inside. But maybe regulation isn’t important? Air doesn’t cost anything, right?
If the outdoor temperature were constantly 18 °C and sunlight never entered through the windows, this wouldn’t be a problem. Continuous ventilation would work just fine. However, such climates exist in very few places. And in those locations, mechanical ventilation is often unnecessary anyway—just install window screens and that’s enough.
As soon as buildings require heating or cooling, the situation changes. Houses are constructed to be highly insulated, and without ventilation, heating and cooling costs would be relatively modest. But when people occupy a building, ventilation becomes essential. Even though ventilation systems include heat exchangers, moisture recovery units, and other technologies, they still operate at a certain efficiency level. This means that in winter indoor air becomes dry, energy is carried out of the building through ventilation, and electricity bills still need to be paid at the end of the month. With rising energy prices, heating and cooling are far from cheap. Demand-controlled ventilation can reduce ventilation-related energy losses by up to half. 💨
Many things in the world are done simply out of habit. For a ventilation designer, it’s easy to take the previous project and copy the same solution into a new building. A solution that complies with standards may still be either wasteful or insufficient. Using the water analogy again: a tap that constantly drips—too little when you need more, and unnecessary waste when you don’t.
Times have changed. New technology is here. Today it is possible to implement demand-controlled ventilation without spending a fortune. It is becoming as self-evident as having a faucet at the end of a water pipe. 🏠⚙️