A longitudinal study has revealed that 50% of New Zealand children sleep in rooms that fall below the expected standard for thermal comfort during the winter months. Causes include older insulation and glazing standards for residential homes, poor materials, inadequate ventilation, and residents being unable to afford heating. These combined factors result in poor indoor environmental quality (IEQ). This paper aims to analyse experimentally and computationally the thermal comfort in a bedroom occupied by two children (aged eight and three) from 19:00 to 7:00. The experiment was carried out during June 2021. The measured data were particulate matter (PM2.5), relative humidity (RH%), and air temperature (, captured with an air image sensor. In order to find appropriate thermal comfort parameters, computational fluid dynamics (CFD) models with four heat pump temperature settings (19, 20, 21 and 22 were investigated to assess the predicted mean vote (PMV), predicted percentage dissatisfied (PPD) and the local air quality index (LAQI) for the expired air. Measurements and CFD results show that setting the heat pump temperature to 22 is aligned with the 1.7 Metabolic (MET) - EN ISO 7730, 2005 and ASHRAE 55 recommendation for thermal sensation and the indoor PM2.5 of 1.058 μg/m3, which meets ASHRAE 62.1, 2019 and the New Zealand Standard NZS4246:2016.