CO2 included in exhaled breath is often used as a tracer gas when estimation of ventilation aspect in buildings with occupants is performed. In Japan, CO2 production rate written in JIS A 14061974, which revised in 1974, has been referred for the estimation. The CO2 production rate calculation formula given by ASTM D6245-12 can be referred also, however, the formula is based on westerner adult data. Hence, based on Japanese subjects' exhaled breath data obtained by using Douglas bag method with approximately total 170 points, equations for recent Japanese CO2 production rate are developed in this study. Moreover, an equation, whose variables are occupants' height & weight, gender, age and Met, is used for estimating ventilation aspects in single zone with occupants aiming at accuracy testing.
Firstly, a simple equation (9) is derived with regression analysis using 23 subjects and 3 testing activities data. The equation requires AD (Japanese body surface area given by equation (6)) Met and CG (coefficient of gender as male: 1 and female: 0).
Secondly, aiming at expanding the targets, equation (9) is transformed and verified by using additional testing whose conditions are shown in Table7 and 8. The obtained 20s males' exhaled breath data is used to derive the equation (10) whose coefficient of deamination is larger than the equation (9) shown in Fig. 4. Then, the equation (10) is added a variable Ca (coefficient of age given by table9) and is transformed into the equation (11) whose coefficient of deamination is larger than the equation (9) shown in Fig. 5. Also, the equation (10) is added a variable Cg (coefficient of gender male: 1.0 and female: 0.73 determined by Table9) and is transformed into equation (12) whose coefficient of deamination is larger than the equation (9) shown in Fig. 6. As a result, the equation (13) is derived and its coefficient of deamination is larger than the equation (9) shown in Fig. 7.
With substituting CO2 production rate given by the equation (13), ASTM and JIS, into the equation (14), calculated CO2 concentration are compared to the measured value obtained in single zones with the conditions shown in Table11 with employing testing instruments shown in Table10. The experimental results are shown in Fig. 10, 11, 12, 13 and 14. From the experimental results, calculated CO2 concentration of present work shows the closest to the measured value compared with the other standards’ value. Therefore, these results can allow estimating more correct ventilation aspects with Japanese occupants.
