61–70 of 101 posts
I may be missing something (perhaps OP doesn't have windows?) but I open my windows in all the rooms a couple of times per day (in the morning and usually in the afternoon-evening). Isn't that enough?
Not being snarky, but a window is one of the best options. Air conditioners can often be your worst option, as the air is recirculated more aggressively. We use a window fan that has multiple settings: circulate, ingress, egress. I find that no matter what setting you use, air is recirculated significantly well. On hot days, the fan is set on egress. This seems to do a really great job of removing excess CO2 while no…
> We also find that simply cracking the windows in the winter makes a large and measurable difference in CO2, but not with heat. Have you maybe done measurements of what difference between the inside and outside temperature is enough to reduce CO2 without a fan?
What we've found is that in the winter putting two windows open a crack makes a very significant different in CO2 and radon builup. CO2 without the cracked windows will be around 1200 or more, while with cracked windows can be as low as 600-800. Not perfect, but like I said, a major improvement. I don't have a precise way to measure if the heat comes off more often, but my experience is that it does not.
Opening a window can be an option. So can an open bedroom door.
The best option to me is to just leave your air handler fan set to "on" rather than "auto". Of course you need forced air for this. My house is relatively newer and moderately sized. It still seems to keep the whole house CO2 levels like 50-100ppm over outdoor levels. The bonus here if you're looking for "air quality" and nor just CO2 is that your air handler filter should catch many particulates (although most aren't capable of high merv ratings, it still seems to help).
Energy recovery ventilator. It will exchange indoor air with outdoor air while maintaining indoor heat and humidity. Unfortunately small window mounted models are hard to come by. Most are whole-home systems.
There is no small scale human comparable in room CO2 removal bio/tech. Human breath will increase CO2 in a closed room on the order of many hundreds of ppm over hours, while even "superplants" like those in an Algen Air will decrease it at best on the order of low tens. We need improvements of two orders of magnitude to have room scale impact. So the only answer is "fresh" air ventilation.
Of course the tech exists, it's just not common. Some submersible tech and space tech used rebreathers or scrubbers to remove CO2 and increase O2 levels. Of course the reason it's not common is that outside of those use cases you can generally just open a window.
It’s typical for bedrooms to have a ACH (Air Changes per Hour) rate of between 0.35 and 1 So the CO2 is removed regularly.
Earlier quoted context omitted.
Also if you live in an area with low humidity look into getting a swamp cooler. It won’t make the air as cold as AC but I personally prefer it
Swamp coolers can get really nasty and smelly due to being the perfect breeding ground for spores and other nasties.
Earlier quoted context omitted.
Also if you live in an area with low humidity look into getting a swamp cooler. It won’t make the air as cold as AC but I personally prefer it
Swamp coolers can get really nasty and smelly due to being the perfect breeding ground for spores and other nasties.
Not being snarky, but a window is one of the best options. Air conditioners can often be your worst option, as the air is recirculated more aggressively. We use a window fan that has multiple settings: circulate, ingress, egress. I find that no matter what setting you use, air is recirculated significantly well. On hot days, the fan is set on egress. This seems to do a really great job of removing excess CO2 while no…
> We also find that simply cracking the windows in the winter makes a large and measurable difference in CO2, but not with heat. Have you maybe done measurements of what difference between the inside and outside temperature is enough to reduce CO2 without a fan?
Imagine a completely closed room surrounded by open atmosphere with the room air having twice the number of CO₂ molecules per m^3 as the open atmosphere. The room air and the outside air are at the same temperature.
Now imagine opening a small vent in the room, and consider what happens to the air close to the vent. Molecules near the vent and moving toward it have a chance of crossing to the other side. At the vent we have a constant flow of molecules from inside to outside and a constant flow of molecules from outside to inside.
What counts as "near" depends on the mean free path, which is proportional to temperature. With the temperatures the same the mean free path will be about the same.
Since there are twice as many CO₂ molecules near the vent on the inside, twice as many CO₂ molecules will be flowing out of the room as are flowing in.
A temperature difference would increase this, by increasing the mean free path on the hot side which increases what counts as "near" on that side. But what matters is what the temperature is above absolute 0. For a room at 40℃ (104℉) and an outside at 0℃ (32℉) that's only about a 15% temperature difference.
Earlier quoted context omitted.
> We also find that simply cracking the windows in the winter makes a large and measurable difference in CO2, but not with heat. Have you maybe done measurements of what difference between the inside and outside temperature is enough to reduce CO2 without a fan?
Temperature isn't going to be much of a factor at the temperatures and temperature differences humans encounter in their homes. The dominant factor in CO₂ exchange is the difference in CO₂ concentrations. Imagine a completely closed room surrounded by open atmosphere with the room air having twice the number of CO₂ molecules per m^3 as the open atmosphere. The room air and the outside air are at the same temperature.…