The work presented in this paper is aimed at the definition of tracer gas experimental procedures for measuring the air change rate, the age of air and the air change efficiency in real buildings under mechanical ventilation conditions. The measurement procedures, based on the decay method, were validated in a special experimental chamber and implemented in two rooms of a building under real operating conditions. Measurements of volumetric flow rate through the air ducts of two buildings, performed by means of the constant emission rate method, will be shown and commented.
This paper reports the findings of a pilot field study carried out to investigate the internal and external air pollution levels of two adjacent buildings, one naturally-ventilated and the other air-conditioned in an urban area, to investigate their relative attenuation of external pollution levels and to compare internal levels with existing air quality guidelines. Concentration levels of sulphur dioxide, nitrogen oxides, carbon monoxide and carbon dioxide were monitored.
A condition often assumed when designing a naturally ventilated building is where air enters at low level and leaves at high level due to the stack effect. It then follows that, at upper levels, the air may be relatively 'stale' since it has previously passed through the lower storeys. An analogous situation may arise when wind is blowing, in which the air entering through the windward face becomes stale as it passes through the building to the downwind sections. It is not well understood how ventilation may, in reality, be affected by this.
The present paper presents results from measurements of outdoor airflow rates and air change rates carried out simultaneously with measurements of the indoor concentration of carbon dioxide (CO2 ) . The measurements were made both under controlled laboratory conditions and in the field. The field experiments were performed in a conference room, an assembly hall and an office room, and the laboratory investigation was carried out in a 19 m³ test chamber.