We build carbon dioxide monitors and controllers, so we spend our days looking at CO2 data from real Indian rooms, classrooms, sheds and greenhouses. This is what the numbers actually mean — what the research supports, what it does not, and what to do about it.
Start here · the five that matter most
The human side: homes, offices, classrooms, and what the numbers mean.
What 400, 1,000, 2,000 and 5,000 ppm actually mean — and why sealed Indian rooms sit at the wrong end of the chart.
15 August 2026Which sensor type to buy, where to put it, how to read the result — and the four mistakes that produce a meaningless number.
15 August 2026A purifier removes particles. CO₂ is a gas — it goes straight through. Two different problems, and the fixes pull in opposite directions.
15 August 2026Eight hours, a shut door and a running AC. The arithmetic of why the room you sleep in is the worst-ventilated room you use.
15 August 2026Forty students, one closed room, and the published link between ventilation rate and test scores. This is an academic issue, not a comfort one.
15 August 2026Where the 1,000 ppm number actually comes from — and why ASHRAE 62.1 does not contain a CO₂ limit at all.
15 August 2026Symptoms that get better when people leave the building. Here is the cheap CO₂ test that tells you whether it is ventilation.
15 August 2026Ventilating an empty room costs money twice. Here is where the saving actually comes from, and how to estimate yours.
15 August 2026Sealed windows, split ACs, purifiers. Every decision was right on its own. Together they built a home with no air exchange.
Mushrooms, greenhouses and indoor growing — where CO₂ is an input, not a pollutant.
High CO₂ during spawn run, low CO₂ during fruiting. The exact bands, and why getting the switch wrong costs you the flush.
15 August 2026Agaricus needs high CO₂ during spawn run and case run, then a controlled drop to pin. The drop is the whole crop.
15 August 2026Nine times out of ten it is CO₂ during fruiting. How to confirm it and rule out the alternatives.
26 September 2026Five things decide whether a CO₂ meter is useful in a mushroom room. Price is not one of them.
26 September 2026Rules of thumb for people do not work here. The load is the crop, and you can measure it in half an hour.
26 September 2026India's summer mushroom. Its hardest problem is getting fresh air into a hot room without drying the beds.
26 September 2026A long spawn run, a cold trigger, then a cool, humid, well-ventilated room. In India, the last part is the hard one.
15 August 2026The published gains are real. So are the conditions attached to them — and an Indian polyhouse breaks several of those conditions.
15 August 2026Sealed rooms deplete below ambient within an hour of lights-on — then accumulate at night. Two opposite problems, one measurement.
Buy the VentPlus CO2 monitor online
Everything on this blog comes out of building and deploying CO2 monitors and controllers in Indian buildings and farms. If you want the level in your own room measured and held down automatically, this is the unit that does it.
₹8,499 inclusive of 18% GST and courier delivery anywhere in India
Questions before you order? Call +91 99170 80700 or email info@ventplus.in.