Carbon Dioxide Concentration in the Bedroom for Various Natural Ventilation Modes

The concentration of carbon dioxide (CO₂), respectively healthy and suitable hygienic indoor environment, is one of the current issues. Residence rooms, excluding rooms in family-run facilities and accommodation units, should be ventilated to comply with a maximum permissible carbon dioxide concentration of 1500 ppm during the stay of people. Many researches have shown that the indoor environmental quality has a significant effect on the incidence of health problems (Sick Building Syndrome, SBS). Nowadays, there are a number of grant programs to support energy-saving buildings, which resulted in massive thermal insulation of all types of buildings. Buildings are nearly airtight closed to reduce the energy losses, and the owners, under the vision of energy and financial savings, almost do not open the windows. It is quite certain that these buildings are inadequate in terms of air quality. The exception is where the air-conditioning units are installed. The experiment measuring the concentration of carbon dioxide in the bedroom is executed in March within a week. Measuring in the winter months is crucial for the evaluation of results because it is difficult to set up an ideal regime for natural ventilation during the winter. The supply of fresh air is achieved by natural ventilation by tilting window but the result is a low temperature (cold) in the interior. The experiment is carried out in a three-room apartment in České Budějovice with newly installed plastic till & turn windows with insulating double glazing. Window wings also allow opening of the tilting position (tilt) and micro-ventilation. The observed bedroom has a floor area of 14.5 m². Two adults live in the apartment. The concentrations of carbon dioxide overnight are assessed under different modes of natural ventilation by tilt & turn window combined with open interior doors to other rooms. The results show a significant effect of ventilation on the air quality. Data proves that only natural ventilation through the new tight windows in renovated apartment buildings is inadequate.