| Tartalmi leírás: |
Retrofit of the old building stock presents a good possibility to reduce the energy consumption. However, as the envelopes of old buildings become tighter, a risk increases that the fresh outside air supplied to the indoor environment by natural infiltration can decrease below the amounts required for a comfortable indoor environment, especially in buildings where mechanical ventilation has not been installed. This study presents an efficient method to measure the ventilation intensity, demonstrated on a 40-years old high-rise office building after a complete envelope retrofit. The well-established tracer gas decay and tracer gas step-up method were employed to obtain the ventilation intensity, using the natural CO<sub>2</sub> produced by the occupants as the tracer gas. The measured values of the air change rate were between 0.1 and 0.7 1/h for the simple façade, whereas it ranged from 0.2 to 0.5 1/h for the double skin façade, with the windows closed. The level of compliance with ventilation requirements varied, depending on the standard and the philosophy adopted.
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