An Experimental Validation of an Indoor Radon Model that examines Energy Retrofit Buildings

The modelling framework IAPPEM was redeveloped to predict indoor radon concentrations in dwellings that have undergone an energy retrofit, and have experienced a consequent air tightness change. The framework is flexible, and allows for simulations to be carried out under various pre-retrofit radon concentration levels, multi-zone building geometries, ventilation configurations and retrofit types. However, detailed real-time radon concentration and ventilation data is necessary for model validation, and such data is non-existent in the Irish context. The generation of these data, which allows for full model validation and testing, is the focus of the current study. The objectives of the current study are to (i) fully characterise the ventilation status of selected Irish dwellings, through measurement, and determine the real-time radon concentrations therein (ii) parameterise the model for these selected dwellings, and make comparative predictions of radon concentrations. The current study focused on measuring hourly radon concentrations, using real-time radon monitors, in dwellings that are representative of the buildings stock undergoing energy retrofit. Each dwelling was monitored for a week-long period to establish time-varying fluctuations in indoor radon concentrations and obtain data on the minimum and maximum range. In addition, air exchange was measured using the tracer gas decay method with CO2 as the tracer. Air exchange comprised of eight selected hourly measurements per dwelling over each measurement week to ensure that the effect of meteorological variations was captured. The model will predict indoor radon concentrations based on local meteorological conditions, building characteristics and in-situ characterisation of radon entry rates derived from experimental measurements. The model’s output will be compared with the hourly radon concentrations collected during the sampling period. Time-series analysis will be carried out, comparing experimental and predicted indoor radon concentrations.