Assessing the impact of reused materials on indoor air quality

The desire to reduce the carbon footprint of buildings and the growing strain on construction material supplies are prompting authorities in some countries to encourage the development of re-use. Doing so raises many questions, however, from the construction costs and organisation standpoints as well as regarding the structural quality of these materials and their potential effects on human health.

Aurore Pfister, an engineer in one of Artelia’s Environmental Design teams, explains the research work currently underway to characterise the impact of reused materials on indoor air quality in buildings.

Why are you combining these two concepts of “reusing materials” and “indoor air quality”?
For one thing, the reused materials sector is starting to become structured, while still having many questions to answer. The latest environmental regulations in France (RE 2020 in particular) set some highly ambitious targets to decarbonise the building sector. To meet these targets we need to develop reuse, because the carbon footprint of reused materials is almost nil, as opposed to that of new materials, which generate large amounts of CO2 (during extraction, processing, transport, use, and end-of-life disposal).
However, reusing materials generates a conflict with certain other requirements. To obtain a high level of environmental certification for a building (BREEAM, WELL, LEED, BBCA, etc.), for example, you have to be able to prove that the materials used release few, if any, pollutants into the air. Labelling exists for new materials, but not for reused materials, which are all too often disregarded as a result.
It is this obstacle – caused by two conflicting requirements – that we have set out to remove, by studying the nature and quantity of pollutants released into the air by reused materials.

You are conducting this research with the Scientific and Technical Centre for Building (CSTB) and the University of La Rochelle. How did this partnership come into being?
Artelia and the CSTB have been working together for many years. This collaboration was cemented in 2019 with the signature of a research partnership, and a first application agreement focusing on indoor air quality. The “circular economy” teams at the CSTB and Artelia are also conducting a number of joint research projects, including the programme to define criteria and indicators for developing scientific bases with which to characterise the circular economy in the building sector. The CSTB is also developing simulation tools on the topic of indoor air quality.
Mindful of this lack of knowledge of the impacts of reused materials on indoor air quality, we have decided to instigate a PhD thesis on the topic, in partnership with the Laboratory of Engineering Sciences for the Environment (LaSIE), a joint research unit bringing together the University of La Rochelle and the French National Centre for Scientific Research (CNRS) which has also been working for a long time with the CSTB on materials subject to environmental constraints. Our PhD student Fatimata Syll started working on this thesis in 2023.

What is the focus for Fatimata Syll’s thesis?
It involves carrying out a series of measurements on reused materials to quantify and qualify the emissions they produce. During her first year, we helped her select a number of materials and pollutants to be examined as a priority. Her research will hence focus on the materials most commonly used (parquet flooring, carpet, etc.), leaving aside the most inert ones such as glass and metal. Similarly, as regards pollutants, she is concentrating on volatile organic compounds (VOC), which are carcinogenic. In short, we have targeted the substances taken into account in labels on new materials, to simplify comparisons.
The list is almost finalised, and we have already started some of the tests. We have been able to draw on our in-house reused materials management platform, “Urban Ressources ”, to identify and access some interesting sources. We are also looking at emissions from material systems, also called multi-layer systems, such as a floor and a carpet, to see whether one can neutralise some of the emissions from the other, and whether preference needs to be given to any specific treatments when materials are being packaged for reuse.

What do you expect to achieve through this work?
We are looking forward to getting the results so we can build models that will eventually be used to help label reused materials in the same manner as new materials. The aim is for Fatimata to develop her own numerical model so that it can then be integrated into the CSTB’s existing tool. As reused materials are of strategic importance, both in terms of using resources sustainably and decarbonising the building sector, we need to remove the obstacles that are hampering their use.