That really sucks. Sounds like the ventilation system is poorly designed.
I wish that all modern buildings had properly sized FTX / air handling units. These exchange the old air with new air using the heat from the old to warm up the new air and at the same time can have HEPA filters for cleaning the air.
Some years ago I ran a department that did a lot of prototyping and research. One of the things we experimented with was CO2 sensors. Not hugely expensive sensors, but mostly cheap ones since we were mostly interested in relative changes (rather than absolute values) - and seeing what kind of performance you could get out of relatively inexpensive sensors[1].
(This is from memory)
We got a lot of interesting results placing sensors in a bunch of commercial buildings. Most rooms in all buildings we measured couldn't keep the CO2 levels below 1000ppm. In fact, most meeting rooms we measured would struggle to keep below 1200-1300ppm when in use and we regularly saw much worse numbers. In one building all meeting rooms we measured would quickly blow past 1200ppm when in use -- except the meeting room management used. Which tended to hover between 600ppm when not in use and about 800ppm when used (though it was big and rarely more than at 1/4 capacity). I guess that explains why complaints about low air quality fell on deaf ears.
We also discovered why the meeting rooms in the basement were so awful for late meetings. At around 1800 hours or so in the evening, the HVAC shuts down. From what I gather, in a tall building, there are supposed to be mechanisms to prevent air from moving back and CO2 dropping down the HVAC system and pooling in the basement. This one didn't. (In fact, ALL the buildings on the campus had the same problem since they were all built at the same time by the same company). So over a few hours CO2 levels would rise to a level where the sensors max out their range and get saturated. They would stay that way until a couple of hours after the HVAC got switched on in the morning.
People would sometimes use those meeting rooms until late in the evening.
If you use consumer air quality measurement devices, beware that they're not terribly good. CO2 sensors tend to have cross sensitivity to lots of other gases. And cheap (eg less than $400 for just the sensor component) particle sensors tend to be fairly crap.
A lot of sensors we found in HVAC systems are even lower quality than consumer grade stuff I've seen in products.
[1] The sensors we used are often found in premium consumer air quality measurement products. So they aren't dirt cheap, but they also aren't that great.
I wish that all modern buildings had properly sized FTX / air handling units. These exchange the old air with new air using the heat from the old to warm up the new air and at the same time can have HEPA filters for cleaning the air.
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