Tekno Training

Impianti intelligenti per un pianeta mig

Tekno Training

Impianti intelligenti per un pianeta mig

Controlled mechanical ventilation or natural manual ventilation?

2021-11-26 10:54:37

Why is it important to ventilate the rooms? And who wins the comparison?

This is a question I get asked very often:

"Is it better to install a controlled mechanical ventilation system or is it better to resort to the old custom of manually opening the windows for manual ventilation of the house? Which practice allows you to have a better air quality in the rooms?"

To answer, it is necessary to make a simple premise. We spend 90% of our time inside buildings: home, office, school, gym, supermarket, etc ... The air quality inside these environments determines our well-being and therefore proper ventilation is essential. We must realize that in a closed environment, as the hours go by, many pollutants accumulate that we continue to breathe. We remember that through breathing we bring oxygen into the blood, together with all the other substances present in the air, and the blood feeds all our cells ensuring their metabolism.

What are the pollutants that can accumulate in the air of our homes?

Contrary to what one might think, these substances are many and some are even unsuspected!

First of all carbon dioxide! We produce it ourselves, just as a refusal to breathe. The more people there are in an enclosed environment ... the greater the concentration of carbon dioxide which gradually accumulates in the air. The feeling of "stale air", headache, drowsiness and poor concentration are the symptoms we immediately feel as the percentage of carbon dioxide in the air increases.

Cigarette smoking is well established ... it is carcinogenic. Even the passive one! Yet I myself have friends who continue to smoke in the house. Not to mention the people we see smoking in the car most days. Fortunately, smoking is not allowed in the common areas ... but everyone is free to keep their "vices" in their homes. Smoking is another substance that in some homes (obviously those of smokers) can accumulate in risky percentages.

Radon gas is a radioactive gas that rises from the ground and can enter our homes through any cracks and crevices in foundation structures. For the record ... the most responsible for the entry of radon gas into homes are precisely the holes made in the foundation structures for the passage of waste water drainage systems (connection to the sewer) or other service pipes. Well, the problem of radon gas is particularly felt in the Italian region of Friuli: do you remember, in past years, the distribution to citizens of special meters to be buried for a certain time?

Another dangerous substance is formaldehyde.

We are used to thinking that formaldehyde is released above all from those furniture made of chipboard, melamine or "medium density fibreboard" (MDF), that is, all those wooden panels in which extensive use of adhesives is made. Raise your hand if you don't have at least one Ikea piece of furniture at home ... I'm a regular customer too!!

Well, if we think that the origin of formaldehyde is only the furniture ... we are very wrong. Formaldehyde, also called formalin or formol, is always close to us. It is present everywhere: it is a food additive (E240), it is used in glues, resins, solvents, paints, packaging, detergents, soaps, dish detergents, softeners, shoe polishes, hair lotions, nail hardeners, hair lotions, basic dyes, creams, perfumes, mouthwashes, mascara, disinfectants, insecticides, deodorants, fabrics (to fix some dyes), plastic laminates, insulating foams, sound-absorbing materials, carpets, parquet, food packaging, coatings of some cans. In short, can you imagine how much formaldehyde released by all these materials manages to evaporate every day in the air of our rooms?

In 2004, formaldehyde was included among the carcinogenic substances for humans. The World Health Organization has established that the maximum acceptable limit in the home is 0.1 ppm (parts per million = 100 micrograms per cubic meter of air). If inhaled at higher concentrations it can cause irritation to mucous membranes and eyes. You didn't expect it .... did you? I would like to provide some simple food for thought: the preservative E240 is still used today in food, even in high concentrations; smoked fish (smoke generates formaldehyde) can contain up to 1000 ppm of formaldehyde!

To conclude with a flourish (so to speak), I would also like to mention all the other Volatile Organic Compounds (the so-called VOCs) that accumulate subtly in the air of our home. I'm talking about all those products that we normally use for cleaning (floors, tiles, taps, oven, glass surfaces), for washing clothes, for washing dishes, etc ...

Manufacturers of these substances "fool" us simply by adding various fragrances. But we must think carefully about the potential danger of these substances. I invite you to read the instructions for use of any product for cleaning the inside of the oven. Here ... now let's try to think of all the molecules dangerous for our lungs that spread in the air of inhabited environments, day after day ... cleaning after cleaning!


What do we deduce?

In the light of what I have told you so far, we can come to a single and inevitable conclusion:

To try to maintain good air quality inside our home, it is very important to ventilate the rooms, that is, to resort to daily ventilation.

Only with regular ventilation can we "dilute" the pollutants, to reduce and eliminate them. But how can regular ventilation be achieved? And here we return to the initial question: is it sufficient to periodically open the windows or is it better to resort to a VMC (Controlled Mechanical Ventilation) system?


Natural manual ventilation

Adequately ventilating inhabited rooms by periodically opening the windows means operating as follows: opening the windows for 10 minutes every 2 hours. Only in this way is it possible to obtain a correct dilution of the pollutants that inevitably accumulate in our homes. Raise your hand if you are able to guarantee such a procedure at home ... practically impossible! Not to mention that such an operation would seriously undermine our heating system in winter, as well as our air conditioning system in summer, with an inevitable increase in the energy bill.


Controlled mechanical ventilation

A controlled mechanical ventilation system can be managed according to your needs: 24 hours a day, or based on time slots, or based on sensors that continuously detect the percentage of carbon dioxide or humidity in the home, or by varying the flow of treated air based on the presence or absence of people. In short, it is the only system capable of guaranteeing good air quality in our home. There is no need to open the windows, even if it is not prohibited (as some might think). Furthermore, the stale air extracted from inside the living rooms is used to "preheat" the fresh air taken from the outside, with a certain energy saving.


In conclusion...

There is no doubt: with the same volume of renewed air inside the house, the VMC system certainly wins over natural manual ventilation (opening the windows), both in terms of effectiveness and air quality, and in economic terms. Periodic opening of the windows would lead to an increase in heating and cooling costs. The mechanical ventilation system, on the other hand, guarantees excellent air quality and a certain saving on the energy bill, avoiding opening the windows and recovering most of the energy that would be extracted from the rooms together with the stale air. It is no coincidence that this system has become a standard for new buildings in energy class "A" and for the so-called "passive" ones. In case there are still doubts, I invite everyone to pay a visit to any office of the public administration (town hall, institution, etc ...) equipped with a VMC system and compare the feeling that you get unlike any other environment that does not have one. I assure you that the difference can be felt immediately!



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by Marco Colmari
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