Nationwide Investigation of Relationship among Performance of Ventilation System, Ventilation rate and Indoor Air Quality in Airtight Houses

1.A new measuring method for evaluating ventilation rate was developed.2. ventilation rates andindoor air quality in airtight houses in most parts of Japan were investigated by fieldField measurements were carried out in summer and winter for three years. The resultof measurement of airflow at outlet shows that 19 (68%) houses out of 28 indicate a low air change速率,which is lower than 0.5 h The result of ventilation airflow rate by constant concentration方法shows that 9 (43%) houses out of 21 indicate a low air change rate，which is lower than 0.5h . The formaldehyde concentrations in 39 (40%) rooms of 98 exceeded Thecriterion of the guideline from the Ministry of Health，Labor and Welfare of Japan. TVOC concentrations in 52 (53%) rooms of 99 exceeded the criterion ofthe advisable value from the Ministry of Health，Labor and Welfare of Japan. In the residence where the amount of ventilation rates was insufficientchemistry substance concentrations exceeded the criterion of the guideline in manycases.3.Numerical of thermal and ventilation performance on airtight houses sere carried out. Theaccuracy of numerical analysis was checked by comparing numerical simulations and results of fieldmeasurement.4.Solutions to problems in those houses suggested by numerical simulations。

1.A new measuring method for evaluating ventilation rate was developed.2.Ventilation rates and indoor air quality in airtight houses in most parts of Japan were investigated by field measurements. Field measurements were carried out in summer and winter for three years.・The result of measurement of airflow at outlet shows that 19 (68%) houses out of 28 indicate a low air change rate, which is lower than 0.5 h^<-1>.・The result of ventilation airflow rate by constant concentration method shows that 9 (43%) houses out of 21 indicate a low air change rate, which is lower than 0.5h^<-1>.・The formaldehyde concentrations in 39 (40%) rooms of 98 exceeded the criterion of the guideline from the Ministry of Health, Labor and Welfare of Japan.・TVOC concentrations in 52 (53%) rooms of 99 exceeded the criterion of the advisable value from the Ministry of Health, Labor and Welfare of Japan.・In the residence where the amount of ventilation rates was insufficient, chemistry substance concentrations exceeded the criterion of the guideline in many cases.3.Numerical of thermal and ventilation performance on airtight houses sere carried out. The accuracy of numerical analysis was checked by comparing numerical simulations and results of field measurement.4.Solutions to problems in those houses were suggested by numerical simulations.