Impact of construction stages on Indoor Air Quality

Since the turn of the century, alarming data produced by the Indoor Air Quality Observatory (OQAI) have led to changes in French legislation, including, most notably, the introduction of compulsory labelling for construction products (decree no. 2011-321 of 23 March 2011). The suppliers of internal finishes (soft floors finishes, paints) now aim to reduce the pollutant emissions from their products, and designers such as architects and engineering consultancies promote a high level of indoor air quality through the careful selection of finishes materials and the efficient design of ventilation systems. 
Despite these developments, many uncertainties remain with regards to the impact of the construction steps on the indoor air quality levels achieved in the in-use final constructed building: material and ductwork storage conditions (exposure to moisture, dust), composition of the laying and bonding products (primary, gaskets, sealants, etc.). At the same time, recent energy performance regulations have obliged planners to make buildings more airtight. Although this has certainly helped to reduce energy consumption and improve users’ comfort, it poses a challenge insofar as the management of humidity during the construction phase is concerned. Indeed, during construction, buildings are not mechanically ventilated at all. As a result, the water vapour produced as various materials dry (especially concrete) cannot be expelled. It is no coincidence that industry experts and professional bodies (Construction Quality Agency) are reporting the growth of mould on various materials (insulation, drywall, paint etc.) with greater frequency.  
The objective of the CHAllenges with Indoor Air Quality during Building Construction (ICHAQAI) scientific project was twofold: firstly, to identify and characterize the different elements that can have a detrimental impact on the indoor air quality during construction; secondly, to propose solutions that will enable professionals to reduce the negative impacts of construction on the indoor air quality of the future constructed building ‘in-use’. Measurements were performed on two representative projects, including chemical and microbiological analyses of dust sampled from ventilation ducts, and complete indoor air quality analyses after each construction stage. Finally, remediation solutions were proposed, including ventilation products protection, and provisory ventilation solutions for construction stages.