Detailed characterization of bedroom ventilation during heating season in a naturally ventilated semi-detached house and a mechanically ventilated apartment

Bedroom ventilation is crucial for providing good indoor air quality, which may contribute to achieving undisturbed sleep. This study presents a detailed characterization of bedroom carbon dioxide (CO₂) profiles and ventilation during the heating season in Denmark. The measurements were made in a naturally ventilated (NV) semi-detached house, equipped with trickle vents on the windows and doors (augmented if needed with exhaust fans), and a mechanically ventilated (MV) apartment. The location of sensors in and around the immediate breathing zone of a sleeping person had measurable effect on the absolute level of CO₂ only in the NV bedroom and not in the MV bedroom. Using the decay of occupant-generated CO₂, the estimated breathing zone air change rate (ACR) was around 0.4 h⁻¹ and 0.6 h⁻¹ for the NV and MV bedrooms respectively. This was adequate for an average breathing zone CO₂ level of 1000 ppm for the MV bedroom but not for the NV bedroom. The CO₂ emission rate of 7.9–10.9 L/h.person during sleep, obtained from bedroom CO₂ measurements, was lower than the estimated values of 12.8–13.9 L/h.person, using currently proposed methods in standards. Thermal comfort parameters during all the experimental sessions in both bedrooms were well within recommended levels.