A life cycle approach to indoor air quality in designing sustainable buildings: Human health impacts of three inner and outer insulations

This paper aims to develop a Life Cycle Assessment-based methodology to assess and compare the potential burden shifting between indoor air quality and energy consumption, as well as between the building construction and use stages, focusing on three insulation materials. We model the complete cause-to-effect chain to determine the mass of substances initially encapsulated inside the construction materials emitted into the indoor and outdoor compartment and further human intake, as well as the energy consumption needed for use stage heating.We found that human health damage due to indoor exposure is dominant over outdoor exposure for all insulation materials, except extruded polystyrene due to the off-gassing of tetrafluoroethane which has a high global warming potential. From a material life cycle perspective, the damage related to indoor emissions during the use stage is substantial for polyurethane foam, due to formaldehyde for both inner and outer insulations and also to Tris (1-chloro-2-propyl) phosphate for outer insulation, while restricted for polystyrene. Total damages on human health depend on building materials production, their emissions during use stage, and impacts related to energy load. They are minimized with a 20-25 cm outer insulation combined with a heat exchanger to ensure sufficient air quality while maximizing solar gain and minimizing air renewal-related heat losses.This methodology is valuable in addressing the trade-off between energy and exposure to materials-related emissions during building use stage, as a function of insulation thickness and air renewal rate, and paves the way to optimize the design of more sustainable buildings.