Be careful of ventilation for home telework "Air conditioner heating"!

Air conditioner heating is popular because of its high safety that does not pollute the air.Isn't there a lot of people who increase the sealing of the room and try to save power?

But there is a pitfall here.It is an increase in carbon dioxide concentration due to human breathing.Especially in eco -houses, which have increased confidentiality in recent years, natural ventilation due to the "gap wind" cannot be expected, and systematic ventilation is required, and in the worst case, there is a risk of harm to health.

If you have an increase in home time due to telework, why not focus on "carbon dioxide concentration" this winter?

This article proposes experimental results at home and solutions using home appliances.

■ Is carbon dioxide harmful in the first place?

Carbon dioxide is attracting attention as the leading greenhouse gas, but is generally recognized as harmless to the human body.However, it is said that higher concentrations can affect health, and according to the Building Standards Law revised in 2003, the density of carbon dioxide in the living room is appropriate for all houses (24) for all houses (24The time ventilation system is required.

【二酸化炭素濃度と人体に及ぼす影響の目安】（各種指標より独自に整理）

■ Experiment!What is the carbon dioxide level during telework?

Assuming a telework, I measured the carbon dioxide concentration in my work room.In the six tatami mats of reinforced concrete condominiums with relatively airtightness, the window, door, and ventilation entrance are closed, and there is one adult.

The equipment used for the measurement is the RAS-Fi CO2 sensor "RS-WFCO2" of Latock System Co., Ltd., which is equipped with a high-precision CO2 sensor "SCD40".It is compatible with Wi-Fi, so you can check the carbon dioxide concentration on the smartphone application screen.In recent years, ventilation has been recommended as a countermeasure against colon virus, and many carbon dioxide concentration measuring machines have been commercialized, so anyone should be able to obtain them.

As a result of the experiment, it was found that the carbon dioxide concentration reached 1,000 ppm in just one hour, like a graph, and continued to rise.The measurement was repeated under the same conditions for a few days, but in general, it was nearly 1,500 ppm in 2 hours.In other words, if you keep up with a telework for 2 hours and 6 tatami mats, you will feel drowsiness and discomfort, and you can cause lack of concentration.

In recent years, there are cases in which a dedicated room of about 3 tatami mats for home telework is provided, so it is necessary to be more careful in such small spaces.

■ Be careful when sleeping!

The concentration of carbon dioxide seems to be necessary to pay attention to bedtime.The above -mentioned graph close the windows, doors, and ventilations between 6 tatami mats, indicating a change in carbon dioxide concentration over 10 hours with one adult.You can see that it reaches 2,000 ppm in about 5 hours and is unpleasant.You need to be more careful because you may not have any subjective symptoms during sleep, as it may last a few hours.

By the way, if the day is measured again with the ventilation opening open, as shown in the following graph, it will be flat and flattened to about 1,300 ppm.I was able to confirm a significant improvement than when the ventilation port was closed, but I was worried that it was chilly due to the invasion of cold outside air, as the state of exceeding 1,000 ppm for a long time.。

■ What is the solution?

Even if the ventilation equipment (24 -hour ventilation system) is operated normally, the telework room and bedroom are not always ventilated.It is effective to open the ventilation, windows, or open the door to ventilate, but there is still a lack of ventilation, and if you do too much ventilation, the efficiency of air conditioning will decrease and the winter will get cold.The utility bill is also high.

The first thing I would recommend is to introduce a device that can measure carbon dioxide concentration and make it visualize carbon dioxide concentration.In the case of the author's house, it was found that the ventilation port and windows were closed, and the doors on the corridor of the room could be opened by about 30 cm, so there was no extreme temperature change and it could keep about 1,000 ppm or less.

Experimenting some ventilation patterns, depending on each home or room, you will find the optimal solution.

■ Can't solve it with home appliances?

In terms of air quality, "air purifier" comes to mind, but at this time there is no product that can absorb carbon dioxide.As for the air conditioner, the number of products with ventilation functions is increasing, and these can be expected to have a certain ventilation effect.One step forward is a combination of the air conditioner equipped with Daikin ventilation function and "BESIDE" equipped with a CO2 sensor.When the carbon dioxide concentration increases, the air conditioner can be driven automatically.In the future, these functions may be easier to use as an air conditioner standard function.

In addition, there are products such as a dweller with a heat exchange function that can be retrofitted to a house (eg Mitsubishi Electric "Rosnai VL-10SR3").

In other words, "ventilation" is required for carbon dioxide measures, and if you want to reduce the energy loss of air conditioning, it is a good idea to consider a thermal replacement ventilation fan.

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It can be said that recent housing -density and air conditioning heating have increased the likelihood of ventilation.Carbon dioxide is invisible and it is difficult to remember the subjective symptoms, so if you start this article, measure the carbon dioxide concentration and lead to a comfortable and healthy and healthy ventilation practice that suits your home.I'm happy.