Effective flow area estimation method using a gas

The objective of this paper is to present a new method for estimating effective flow areas not only in the external wall of a house but also in the internal walls between rooms using only one type of tracer gas. The discharge coefficient of each wall and the pressure in each room—which are unknown variables—are determined using nonlinear simultaneous equations, which consist of balance equations for the air mass and tracer-gas concentration in the rooms. To verify the validity of this method, we performed a numerical experiment. We defined the values of the discharge coefficient of each wall, and then simulated changes in the temperature and tracer-gas concentration. We then estimated the discharge coefficient of each wall from the simulated temperature and concentration values using the method. Because it was confirmed that the estimated values were equivalent to the defined values, the validity of this method was verified.