Management of Thermal Comfort in Smart Homes: Assessing Radiator Performance under Controlled Seasonal Ventilation and Humidity Conditions

This study evaluates the thermal comfort performance of a conventional hydronic radiator system in a smart home under varying seasonal, ventilation and humidity conditions. A transient Reynolds-Averaged Navier-Stokes Computational Fluid Dynamics (RANS-CFD) model, partially supported by sensor-based microclimate measurements, was used to simulate twelve controlled scenarios based on representative summer and winter outdoor boundary temperatures of 20 °C and 5 °C, respectively, with open- and closed-window conditions and relative humidity levels of 30%, 50% and 70%. Thermal comfort was assessed using the Predicted Mean Vote (PMV) and Predicted Percentage of Dissatisfied (PPD) indices. The results show that the radiator system maintained slightly warm but near-acceptable comfort in summer closed-window cases, but failed to achieve acceptable comfort in winter, even with windows closed. Open-window conditions caused substantial comfort deterioration through ventilation-driven heat loss, with the winter open-window cases producing severe cold discomfort (PMV < −2.18, PPD > 82%). Within the adopted air-temperature-based approximation of mean radiant temperature, regression analysis showed that air temperature was the dominant comfort-related variable, while relative humidity had only a weak linear influence. CFD-based spatial analysis predicted clear thermal non-uniformity, particularly in the stair/landing region, where buoyancy-driven warm-air transport and local heat accumulation produced persistent anomaly. Overall, the findings indicate that effective smart radiator control in modern dwellings should prioritise window-state awareness, zonal interpretation and spatial comfort mapping, while treating humidity as a secondary comfort variable.