A perfectly cool room, a not-so-restful night
Imagine this: you’re enjoying a perfect summer getaway. Outside, temperatures are climbing above 35°C, while the air conditioning keeps your room at a comfortable 24°C. You go to bed at midnight expecting a cool, restful night, only to wake up at 8 AM with a dull headache and that familiar feeling of morning brain fog.
So, what happened?
During a series of summer measurements, we tracked this exact scenario. With the doors and windows tightly closed overnight, the CO2 concentration rose from 1300 ppm to an alarming 3100 ppm—and it was still increasing.
In homes without mechanical ventilation, which remain common across much of the EU, the quickest solution is simply to open the windows and let fresh air circulate.
A practical compromise
To avoid the same problem the following morning, we tested a practical compromise: leaving a window slightly open while keeping the air conditioning on. It does increase electricity consumption, but it kept CO2 levels below 1500 ppm and made the indoor environment noticeably more comfortable.
Want to understand how carbon dioxide levels can affect your comfort and well-being? Explore the details here.