The energy crisis and concern about global warming have led to drastic measures to save energy in homes by improving their insulation.
What is the impact of this insulation on indoor air quality?
As part of the "Mesqualair" project, researchers from the University of Engineering and Architecture in Fribourg, the Institut universitaire romand de santé au travail, Lausanne, and TOXpro SA in Geneva have attempted to answer this question.
The indoor air in 650 new and renovated houses (including houses with the Swiss "Minergie" label) was monitored during three measurement campaigns.
Basic IAQ parameters were analysed, namely Volatile Organic Compounds (VOCs), Radon and mould.
How were indoor air quality measurements taken?
Reliable and accurate measurement of indoor air pollution requires analysis by a specialized laboratory. This is the only way to assess the contamination of a building:
- Volatile Organic Compounds (VOCs) are sampled with a passive sensor installed for one week in the main bedroom, to be then analysed in the laboratory in order to qualify and quantify the gaseous molecules present in the air.
- The possible radon content is measured by a dosimeter exposed for 3 months in the living room.
- Finally, the moulds are sampled by an electrostatic sensor, a wipe or an adhesive tape and then analysed in the laboratory to identify the mould strains.
What is the indoor air quality in the dwellings studied?
Among the pollutants identified in the dwellings, more than 70 different VOCs were detected and identified. Conventional indoor air pollutants such as toluene, formaldehyde and hexaldehyde are found in all dwellings.
The study shows that increased pollution is observed when a garage attached to the dwelling is present.
Mould problems are most prevalent in renovated homes. It is noted that the difficulty of identifying hidden moulds can be detrimental to the health of the inhabitants as well as to the deterioration of the building.
Only 10% of houses with radon levels above the reference value (300 Bq/m3) have been identified, with a higher recurrence in renovated buildings.
What are the consequences of good insulation on indoor air quality?
Not surprisingly, insulation can be a problem for IAQ. Indeed, improved insulation generally leads to a decrease in the rate of indoor air exchange and pollutant accumulation.
The results clearly show an increase in biological pollution with the more frequent presence of microscopic fungi (molds), a key factor in the onset of respiratory disease.
For chemical pollution, even if the rates often remain below the reference values, Volatile Organic Compounds are still present, especially in renovated houses. These pollutants cause respiratory tract irritation and aggravate lung pathologies.
The presence of radon (the second cause of lung cancer after smoking) also increases with the lack of ventilation in many well-insulated houses.
It is now obvious that energy renovation or the design of energy-efficient housing must integrate indoor air quality as a parameter of comfort and quality of life.
Testing the indoor air quality of one's home after insulation work?
A quality assessment is therefore essential for new or renovated housing to ensure that insulation investments do not have a negative effect on health and ultimately cost more than they yield.
Efforts related to good building design pay off, since buildings with the "Minergie" label and complying with stricter building standards have lower contamination rates for the 3 types of pollutants studied (VOCs, Mould and Radon).
Based on the principle that indoor air is generally more polluted than outdoor air, it is therefore advisable to be vigilant.
Indoor air checks may reveal a deficiency in ventilation, which must be remedied by better mechanical ventilation or by good management of the openings.
The right gestures also consist in correctly managing cleaning products, do-it-yourself products, cosmetics and home perfumes, limiting their use and placing them in well ventilated areas. Insulation of the garage or cellar may also be recommended.