Modeling VOC-emissions in a building using Laplace networks – simplified models, explicit expressions and typical timescales

New buildings often initially have elevated levels of VOC emissions that negatively affect the perceived indoor air quality. Increased ventilation is therefore commonly used in new buildings to reduce VOC concentrations and speed up the depletion of VOC within the materials. In this work we present a new analytic method, using Laplace networks, for precise prediction and analysis of VOC emissions in new buildings. The method handles multiple materials and is flexible and easily extendable to more complex cases. The method is validated with numerical simulations and used to analyze a room specific time-constant for assessing early-stage emissions. Results show that the time-constant, together with a general eerfc-function, is useful for relating material properties, emitting area and ventilation rates to time. The proposed method is also used to derive several simplified models that predict emissions and concentrations at various stages, giving new insights into the impact from input parameters and relevant timescales. Given its high computational speed, the method is also proven to be suitable for uncertainty analysis when input data is limited. • Laplace Networks is an efficient method for modelling VOC emissions from materials in a room. • The flexibility of Laplace Networks enables easy modeling of many real-world situations. • At timescales of days or more, building material emissions are mainly limited by diffusion.