> There currently appears to be an emphasis on CO2 as a particularly Bad Thing, but the research in this paper suggests that CO2 is less of an issue
Research as recent as 2020 indicates that CO2 does not effect things like cognitive functions:
> Poor indoor air quality indicated by elevated indoor CO2 concentrations has been linked with impaired cognitive function, yet current findings of the cognitive impact of CO2 are inconsistent. This review summarizes the results from 37 experimental studies that conducted objective cognitive tests with manipulated CO2 concentrations, either through adding pure CO2 or adjusting ventilation rates (the latter also affects other indoor pollutants). Studies with varied designs suggested that both approaches can affect multiple cognitive functions. In a subset of studies that meet objective criteria for strength and consistency, pure CO2 at a concentration common in indoor environments was only found to affect high-level decision-making measured by the Strategic Management Simulation battery in non-specialized populations, while lower ventilation and accumulation of indoor pollutants, including CO2, could reduce the speed of various functions but leave accuracy unaffected. Major confounding factors include variations in cognitive assessment methods, study designs, individual and populational differences in subjects, and uncertainties in exposure doses. Accordingly, future research is suggested to adopt direct air delivery for precise control of CO2 inhalation, include brain imaging techniques to better understand the underlying mechanisms that link CO2 and cognitive function, and explore the potential interaction between CO2 and other environmental stimuli.
Measuring CO2 can perhaps be a convenient metric on how good the circulation in your living space is as a proxy for other things that are harder to measure: so if you move air to lower CO2, you're probably helping reduce numbers for other things as well.
I can't tell if this research still applies. There currently appears to be an emphasis on CO2 as a particularly Bad Thing, but the research in this paper suggests that CO2 is less of an issue than just temperature in deciding whether a space is pleasant or unpleasant to work in
Thermal comfort is still the number one thing. Visual comfort (primarily glare, but also the frequency spectrum of the light/overall light levels matter too) and ventilation do matter too though. Everybody knows what it’s like to be in a crowded lecture hall with poor ventilation and high CO2 levels leading to drowsiness!
There’s been a big boom in research related to dispersal of things (CO2, biological materials etc) lately though due to the increasing accessibility of CFD to building scientists + COVID.
Thermal comfort isn't as simple as many people think.
Your wall thermometer may give you a reading, but that may only be perhaps half of what you feel in a room. Another large portion is radiant heat emanating from all the objects (furniture, walls, etc) around you:
It's why in an office people can feel cold and complaint to the the facilities folks, but when they should up with a thermometer it reads the 'correct' room temperature (21C or whatever)—the thermometer isn't taking into account the giant glass office windows that are acting like 'anti-radiators' in the winter.
Further, if the temperature is correct, but the humidity is 'high' (>60%) then things will feel hotter:
If you live in an area where it can get humid, it's worth considering getting a whole home dehumidifier: if the temperature is 21C but it's humid, the AC will not kick in—you need an hygrometer (RH%) too.
Haha, yes I know! You also have airspeed, perspiration, metabolic rate, clothing levels, and transients (eg moving from a hot space to a cold space) which all affect the phenomenological experience- but we do consider all of these effects to be wrapped up within the “thermal comfort” term of art.
See the CBE Thermal Comfort Tool to interactively determine comfort bands in relation to various ASHRAE standards for computing thermal comfort with all of these affecting parameters:
Research as recent as 2020 indicates that CO2 does not effect things like cognitive functions:
> Poor indoor air quality indicated by elevated indoor CO2 concentrations has been linked with impaired cognitive function, yet current findings of the cognitive impact of CO2 are inconsistent. This review summarizes the results from 37 experimental studies that conducted objective cognitive tests with manipulated CO2 concentrations, either through adding pure CO2 or adjusting ventilation rates (the latter also affects other indoor pollutants). Studies with varied designs suggested that both approaches can affect multiple cognitive functions. In a subset of studies that meet objective criteria for strength and consistency, pure CO2 at a concentration common in indoor environments was only found to affect high-level decision-making measured by the Strategic Management Simulation battery in non-specialized populations, while lower ventilation and accumulation of indoor pollutants, including CO2, could reduce the speed of various functions but leave accuracy unaffected. Major confounding factors include variations in cognitive assessment methods, study designs, individual and populational differences in subjects, and uncertainties in exposure doses. Accordingly, future research is suggested to adopt direct air delivery for precise control of CO2 inhalation, include brain imaging techniques to better understand the underlying mechanisms that link CO2 and cognitive function, and explore the potential interaction between CO2 and other environmental stimuli.
* https://doi.org/10.1111/ina.12706
* Interview: https://www.youtube.com/watch?v=Lx_H2DwKIuU
You may wish to measure other things if you're worried about health:
* https://www.youtube.com/watch?v=61PQ764XiPY
Measuring CO2 can perhaps be a convenient metric on how good the circulation in your living space is as a proxy for other things that are harder to measure: so if you move air to lower CO2, you're probably helping reduce numbers for other things as well.