“Is heat recovery ventilation really worth it?” is one of the most common questions we hear from future homeowners. The answer lies in the numbers — and they are more convincing than you might expect.
Why You Are Literally Throwing Heat Out the Window Without Heat Recovery Ventilation
In a modern, airtight and well-insulated home, air does not circulate naturally as it did in older, “leaky” houses. If rooms are not ventilated, the air quickly becomes stale, humidity increases and CO₂ levels rise — affecting how you feel, your concentration and your sleep.
The only traditional solution is opening the windows. The problem? During winter, you do not only let stale air out of the house — you also let out all the heat you have paid to produce.
How Heat Recovery Ventilation Changes This
The central heat recovery ventilation system installed in Stela Haus homes works on a simple physical principle: warm stale air leaving the house and fresh cold air entering it travel alongside each other, separated only by a thin aluminium wall. Heat passes through this wall into the incoming fresh air, while the two air streams never mix.
Our system achieves up to 98% heat recovery efficiency. This is the actual efficiency of the heat exchanger, not a marketing figure.
Two Practical Examples (Theoretical Calculation)
Outside temperature: 0°C. Indoor temperature: 22°C.
Without heat recovery ventilation, fresh air enters at 0°C and must be heated by the full 22 degrees. With heat recovery ventilation, the air enters at almost 21.5°C, so it only needs to be heated by around half a degree.
Outside temperature: –10°C. Indoor temperature: 22°C.
Without heat recovery ventilation, fresh air enters at –10°C and must be heated by 32 degrees. With heat recovery ventilation, the air enters at almost 21.4°C. Even in the middle of winter, the air entering the home is already close to room temperature.
These are theoretical calculations and do not account for additional heat losses. However, in practice, deviations from these figures are minimal. Imagine what this means for your monthly heating costs throughout the entire heating season, when your heating system does not have to work overtime every time you ventilate your home.
It Is Not Only About Money — It Is Also About Sleep and Health
Heating savings are only one side of the story. The other, often overlooked benefit is the quality of the air you breathe every day.
Two people sleeping in one bedroom can breathe out enough CO₂ within just a few hours for rising CO₂ levels to cause daytime sleepiness and fatigue, difficulty concentrating, slower thinking and a feeling of having a “heavy head.” Many people attribute this to poor sleep, when the real cause is simply poor indoor air quality.
Central heat recovery ventilation solves this problem automatically, 24 hours a day, without opening windows — whether you are sleeping, at work or it is raining outside.
Does the Investment Pay Off?
Although heat recovery ventilation is not formally mandatory under the Slovenian Rules on Efficient Energy Use in Buildings, it is often essential in modern new-build homes with strict energy-efficiency requirements. It can be necessary to achieve the required energy performance indicators and, therefore, to meet the conditions for obtaining a building permit.
For this reason, central heat recovery ventilation is part of the standard equipment in Stela Haus homes, rather than an optional extra that requires an additional payment.
When you add up lower heating costs during every heating season, reduced maintenance compared with multiple local ventilation units, and improved wellbeing thanks to better indoor air quality, the answer to the question “Is it worth it?” becomes clear.
