Mass-Transfer Air Pollution Modeling in Heritage Buildings

Two simple mass-balance models for estimating the concentration of air pollutants inside buildings are presented for pollutants originating from outdoors or generated indoors. The models can be used to establish average pollution loads on heritage objects inside buildings and assist in risk assessment for conservation. The models can be run with a minimum of data, either based on fixed conditions or as a Monte Carlo simulation based on plausible intervals of the input factors. Input data can be obtained by simple measurements or based on the literature. A museum storage hall in Denmark was used as a test site for demonstrating the models. They were evaluated with regard to the prediction of the indoor/outdoor concentration ratio for ozone and nitrogen dioxide and the build-up concentration of indoor generated organic acids. The pros and cons of such models were discussed, where the main reservation is related to shortcomings when real buildings are more complicated than the single-zone structure of the models. A strength of the models is the easy adaption to an indoor environment and, despite being semi-quantitative at times, the simplicity of the models, which allows for practical everyday use in air quality management of heritage buildings.