Building modeling approach for IAQ assessment: Influence of the main drivers of vapor intrusion from the subsurface

Abstract

Most of the proposed Vapor Intrusion (VI) models are developed assuming a steady indoor environment (i.e., building pressure and air exchange rate). To account for variations in these building conditions, these models are coupled with multizone codes to enable more precise modeling of indoor air pollution. In this paper, semi-empirical VI models are integrated into MATHIS-QAI, a multi-zone ventilation software. This coupled tool allows consideration not only of the impact of the building ventilation system characteristics, airtightness, and foundation type, but also the computation of more realistic pollution scenarios by specifying the lateral separation between the pollution source in the soil and the building. A sensitivity analysis was conducted to quantify the influence of these parameters on the indoor concentration of pollutants. The results showed that the main driving parameter in this event is the source location in the soil. However, a significant impact of the building characteristics and weather conditions on the indoor pollutant concentration was also observed. These characteristics vary significantly from one building to another, necessitating specific and appropriate calculations. The proposed tool, based on nodal modeling, offers an easy-to-use simulation that does not require significant computational resources compared to Computational Fluid Dynamics approaches. This coupling can be utilized for optimal management and reduction of uncertainties in risk assessment. Ultimately, it can serve as a relevant tool in the design and conception of more efficient buildings against VI.