Så mange planter skal du købe for at generere Co2 nok til en hel folkeskoleklasse – eller? - Åbn

That's how many plants you have to buy to generate enough Co2 for an entire primary school class - right?

In this blog post, we throw in aeration and plants in each corner of the ring. Because now imagine if we could get rid of aeration and simply manage with the oxygen the plants generate! Read along here.

Your lungs fill half a tennis court

In a day, you breathe approximately 20,000 times.

When you do that, oxygen is secreted into your bloodstream and into all your cells so your body can function. You can say that the lungs are your most important organ as the whole body depends on your breathing. Therefore, they are also well protected behind your ribs, which both hold the lungs so that they do not collapse, but also ensure protection against blows and knocks from the outside.

Your lungs contain between 3-400,000,000 small alveoli.

And yes, you read that right – it was millions!

In fact, your lungs take up approximately 90 square meters if you could fully unfold them. That's the equivalent of half a tennis court!

Scientists estimate that we have an oxygen consumption of 50 liters per hour. This oxygen comes primarily from plants through photosynthesis. They generate large amounts of oxygen from our waste, carbon dioxide (CO2) sun and nourishment.

But what if we locked ourselves in an airtight chamber? How many plants would we need to survive?

It is the CO2 level that counts

We, like so many others, always recommend airing out regularly. When you open several windows in a room, you will create drafts and the used air in the room will be replaced with new, fresh air from outside. Many are worried about whether the air outside is clean enough for them to dare to ventilate.

However, the alternative is much worse.

In the vast majority of schools, the CO2 level inside reaches more than double the level outside. This is because we excrete CO2 as one of our waste products when we breathe.

CO2 is not dangerous in small quantities, but is used as an indicator of the state of the indoor climate. At the same time, studies show that a level above 1000 parts per million (translated: parts per million) causes headaches, fatigue, increased illness, poor concentration etc.

That is why it is incredibly important that you vent in a school class, as otherwise it directly affects the students' performance.

If the concentration of CO2 exceeds approximately 20,000 parts per million (2%), the level will reach a point where it can kill you. However, it must be said that those levels cannot be achieved in an ordinary room, but require a totally airtight room.

The oxygen also runs out at some point.

If there are 25 students in a classroom of 70 square meters with two meters to the ceiling, they will be surrounded by approximately 140,000 liters of air, of which approximately 30,000 liters is pure oxygen.

With a consumption of 50 liters per person per hour, all the oxygen will in theory be used up after 24 hours.

Remember that this is of course a theoretical example and that it could never happen in reality as the premises are often leaky enough for fresh air to seep in.

Plant vs. ventilation

But how many plants should a school class have in order to achieve a fresh indoor climate with optimal oxygen and CO2 levels?

Scientists estimate that an average person consumes 50 liters of oxygen per hour.

Meanwhile, a leaf emits approx. 5 ml. oxygen per hour.

A person must therefore be in a room with around 10,000 leaves, which corresponds to approximately 300 to 500 plants, in order to produce the right amount of oxygen.

For a school class of 25 students, this amounts to nothing less than 7,500 to 12,500 plants!

It is not only difficult to have so many plants in the classroom, it also becomes an expensive affair.

Purchases of the plants quickly rise to 500,000 to 1 million. kroner, and the weekly watering of all the plants would amount to 1000 liters of water!

If these are small things for you, I also hope you have the 500 free square meters the plants would require of space.

The conclusion is that it is probably both too difficult and costly to rely on plants as the primary source of oxygen in a classroom.


In the opposite ring corner, we have quite ordinary ventilation

With proper ventilation, with two opposite openings, open, all the used air in the room will be blown out of the room in 5-10 minutes, and replaced with fresh renewed air filled with oxygen.

If this happens a suitable number of times a day, and in exactly the right way, the CO2 level will never reach dangerous heights, and the students will not notice the side effects of a bad indoor climate, and it will not even cost the energy bill.

All you need to ensure proper ventilation is SKYEN, which only costs DKK 1,500 per local.

The CLOUD visualizes with its blue/red colors whether the CO2 level in the room is optimal or too high, so the class knows when it is time to ventilate and ensure an optimally low level of CO2.

We call it the world's simplest CO2 indicator – because it is! It was designed in collaboration with primary school students, as they are the ones who have to use it and ventilate in daily life.

Read more about the SKYEN here, or about our brand new concept, Luftens Helte, which gives students a pat on the back for the heroic deed of venting in class.

Back to blog

Leave a comment

Please note, comments need to be approved before they are published.

1 of 4