A method for integrating indoor air quality into the life cycle assessment of buildings: application to the sizing of ventilation rates

Abstract Purpose Life cycle assessment (LCA) is used for building ecodesign purposes, but ecodesign software rarely considers indoor air quality (IAQ). IAQ is critical to human health since we spend about 90% of our time indoors and are exposed to potentially hazardous substances. Its consideration in LCA foreground data could help make adequate design choices (e.g. materials, window layouts, or ventilation rates) and reduce buildings’ impacts on human health while avoiding their transfer to other life cycle stages. Methods To address this gap, we propose a methodology combining building LCA and IAQ models encompassing the whole pathway of the pollutant: from its emission to quantified impacts on human health using the disability-adjusted life years (DALYs) indicator. We account for volatile organic compounds (VOCs) and fine particulate matter (PM 2.5 ) emitted by materials and indoor activities. An optimal ventilation rate that reduces overall health impacts (incl. IAQ) can be identified depending on the building situation (heating device, material, outdoor pollution, etc.). The method’s applicability was demonstrated in a building case study with some offices and a kitchen. Results and discussion PM 2.5 and heating were the primary sources of impacts, respectively ranging from 40 to 94% and 1 to 31% of the total life cycle impacts of each room, which vary from 2500 µDALY/year to 14,200 µDALY/year. Rooms with higher indoor emissions had higher optimal ventilation rates: 1.2 ACH (air changes per hour), 2.9 ACH, and 13.2 ACH in the meeting room, office, and kitchen, respectively. These rates also varied for different heat sources due to their different IAQ and LCA impacts: 2.7 ACH, 5 ACH, and 15 ACH for coal (still a standard fuel in rural Asian countries), gas, and electric fan heating, respectively, in the living room. The combined use of double-flow ventilation to lower heating needs and filters that reduce PM 2.5 concentrations led to a 56% decrease in the total impacts of the meeting room. Conclusions This study shows the method’s applicability to building ecodesign. For instance, distinct optimal ventilation strategies can be devised depending on the room or building’s use. Further development is needed to move toward a regulatory application in public health through representative archetypes, providing general recommendations in the tertiary and residential sectors. More research would be required to integrate IAQ in LCA fully, considering background aspects, which was not considered in this study due to the focus on ecodesign of buildings.