A study that covered all French-speaking Swiss found that energy-efficient renovation work in residential buildings tended to ignore questions about indoor air quality. Research writers, especially from EPFL and the School of Engineering and Architecture Friborg (HEIA-FR), have called for greater attention to this issue.

Researchers from EPFL, the School of Engineering and Architecture Friborg (HEIA-FR) and the Center for Primary Care and Public Health (Unisanté) have conducted extensive studies on the use of residential energy and the concentration of radon, fungi and various organic chemicals in the room – easy organic compounds evaporate (VOC) and aldehydes – in newly built and renovated energy-efficient housing in French-speaking Switzerland. This research, carried out with the support of outside experts, was initiated by the Center for Domestic Air Quality and West Swiss Radon (croqAIR), based in HEIA-FR, which is leading the Mesqualair indoor air quality measurement project. Between 2013 and 2016, researchers sent comprehensive measurement kits and questionnaires to residents of this residence, asking them about the lifestyle and characteristics of their homes. A high response rate gives the team more than enough data to draw conclusive conclusions.

The highest concentrations of these air pollutants – which are known to cause cardiovascular and respiratory diseases, as well as lung cancer and other cancers – are found at home with good wall insulation but no mechanical ventilation or other air circulation systems. This finding has prompted the team to urge government authorities, the construction industry and the general public to pay more attention to indoor air quality issues, citing sustainability and public health.

Regulatory vacuum

Although the Federal Radiology Protection Act of 1994 (revised in 2017) sets limits on the concentration of radon gas, there is no equivalent framework in Switzerland for other pollutants covered by this study. Therefore, the team must look elsewhere as a basis for comparison. The results were published in four separate papers between December 2019 and spring 2020. The most recent, which appeared in the Indoor Air Journal on April 14, 2020, focused on chemical compounds. This paper reveals that while formaldehyde concentrations (released from building materials) without exception are below the limits recommended by the World Health Organization (WHO), French authorities and the Swiss Federal Office of Public Health (FOPH), the measurement exceeds the chronic reference level of exposure set by the Office California Environmental Health Hazard Assessment (OEHHA) in 90% of cases. Likewise, the total VOC concentration in the room (TVOC) is above the recommended FOPH level of 1,000 micrograms per cubic meter of air in 8% of cases.

The researchers found that levels of chemical pollutants were generally lower in buildings equipped with mechanical ventilation systems. They concluded that the high VOC concentration in homes built between 1950 and 1990 was, at least in part, due to three factors: the use of certain construction materials, the lack of mechanical ventilation, and the fact that the installation of energy-efficient insulation reduced natural air. flows between inside and outside the room. An increase in the rate is also found in buildings with garages attached.

The team’s first paper, published in the journal Atmosphere on December 4, 2019, reported measurements of radon in more than 650 dwellings in a three-month period. The results show that, as a general rule, levels in new energy efficient buildings are lower than renovated buildings because new buildings tend to be located in areas with lower radon concentrations and are more likely to be equipped with mechanical ventilation systems. Looking at samples from 60 renovated buildings, the researchers found an increase in radon exposure of 20% when compared to pre-renovation rates, further underlining the need for strong and efficient ventilation. The team also reported higher concentrations in buildings with cellars in areas affected by radon.

Just opening a window is not enough

In a paper, which appeared in early 2020 in Building and Environment, researchers revealed that people who live in renovated homes without mechanical ventilation, more often ventilate their homes than those who live in newly built dwellings with mechanical ventilation systems. But in both cases air renewal was not enough, causing the team to conclude that adequate indoor air quality cannot be achieved by simply opening a window. The latest paper, which has not been published, reports the concentration of fungi and species in 149 dwellings. Like radon, the team found that new energy-efficient dwellings with mechanical ventilation systems provide better protection from mold than renovated buildings. They also report that suburban housing tends to have more visible mold, and greater species diversity, than urban and rural dwellings, and that the presence of mechanical ventilation systems affects the diversity of mushroom species. They also found that such a system helped prevent mold growth by reducing moisture buildup in buildings.

Many solutions

What are the future implications of this research? Dusan Licina, assistant professor of tenure at the EPFL Smart Living Lab in Friborg and one of the co-authors of the paper, believes that this study paves the way for further research on smart windows and low-emission building materials, with an emphasis on the need to monitor indoor air quality in an continously. Joëlle Goyette Pernot, a professor at HEIA-FR and co-authors of another paper, emphasized that air quality requires closer attention: “As researchers, it is our duty to draw the attention of governments, industry and the general public to this problem. . We are currently working with FOPH and Geneva Canton to establish an indoor air quality observatory in French, which is in French. The new facility, the first of its kind in Switzerland, will help to advance our understanding and encourage collaborative research. “

The researchers believe that the ultimate goal of energy efficiency measures is to improve the well-being of residents. “It’s easy to work towards saving energy and the costs that flow from bringing old housing to modern efficiency standards,” Licina said. “But if we ignore the impact of renovation work on indoor air quality, this benefit can be greater than the impact of poor health and productivity. It’s time for the industry to treat this goal not as a competing force, but as two sides of the same coin. “

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