Indoor air quality in buildings

If it is less publicized than the quality of the outside air, the pollution of the indoor air can however also have many consequences on the well-being and the health of the people: olfactory discomfort, drowsiness, skin irritations and of the eyes, but also the appearance or worsening of acute or chronic pathologies: asthma, respiratory allergies, etc.

To alleviate these inconveniences, the decree of March 24, 1982 already introduces the principle of general and permanent ventilation of housing in all seasons. The regulations also indicate that landlords must provide tenants with decent housing that does not reveal any obvious risks to their health and safety and ensure them the peaceful enjoyment of said housing. It is therefore their responsibility to equip homes with adequate ventilation solutions.

Humidity in buildings, an indirect source of pollution

While water vapor is not toxic to humans, humid housing allows molds and mites to proliferate and pollute the indoor air. Molds can cause effects on the health of occupants, either by direct exposure through inhalation of spores, or by direct contact on the skin or eyes. They can also give off a wide range of compounds capable of causing deleterious effects.

There are many sources of humidity in the house: cooking, drying clothes, washing, but also human respiration. For example, an adult produces about 55 g of water vapor per hour, and a laundry about 1 kg over its drying time. Mold mainly develops in damp rooms with poor ventilation, such as bathrooms, on poorly insulated walls or at thermal bridges. Their spores can invade the entire dwelling. According to an ANSES survey, exposure to molds concerns a large proportion of homes: between 14% and 20% of homes in France have visible mold.

A risk of asset degradation

Beyond the health risks, mold also presents heritage damage linked to the degradation of the premises: blisters form under the paint which begins to crack, the plaster crumbles and the wallpapers peel off. Most coatings do not resist the presence of moisture for long. In addition, the water contained in a wet wall carries with it hygroscopic salts which migrate to the surface of the walls and which strongly participate in the detachment of plasters and coatings.

In some cases, humidity can even go so far as to weaken the structure and degrade the solidity of a building. In general, the costs of repairing a dwelling with mold are several thousand euros.

The role of ventilation

Ventilation, the process by which the air inside a building is renewed, aims to contribute to the comfort and health of occupants as well as to the sustainability of the building. Ventilation of confined spaces is an absolute necessity and a regulatory obligation. It must ensure good indoor air quality and optimal thermal and hygrometric comfort. It provides fresh air, dilutes pollutants and evacuates excess humidity.

Several technical solutions exist to ensure the renewal of air in a building by reconciling air renewal needs and energy savings. It should be noted that the regulations applicable to each type of building have an important influence in the choice of a suitable system. The decree of March 24, 1982 made general and permanent ventilation of new housing compulsory: we have since spoken of VMC (controlled mechanical ventilation).

Damaging but easily controllable dysfunctions

To go further, several solutions make it possible to ensure that the indoor air quality complies with standards and to alert owners and occupants as well as possible to the risks of condensation and the development of mold.

It was noted that operating faults (failure, underflow, etc.), often the cause of poor air quality, were rarely identified before the annual maintenance was carried out, sometimes leaving the homes without mechanical air renewal for many months. The VMC box instrumentation can alert on the most impactful faults: thanks to the installation of a differential pressure sensor on the horizontal VMC network, it is possible to detect a failure of the box, insufficient pressure , improper setting of the operating point of the subwoofer, etc. Finally, the detection of relative humidity, a particularly revealing symptom in the heart of the home, provides an alert in the event of excessive humidity and risk of condensation.

Humidity is therefore a real scourge for homes and their occupants, by generating mold which damages property and presents a real health risk. To enjoy their right to breathe the air that does not harm their health, owners, landlords and tenants must more than ever ensure that all the measures and solutions have been deployed in their building, and checked regularly. So that everyone can breathe in peace.

Tribune by Olivier JUNG, Technical and Material Solutions Manager at OCEA Smart Building (LinkedIn) and Riccardo ISSOGLIO (LinkedIn), Sensor expert at OCEA Smart Building (OCEA Group).