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Nowadays, modern windows with standard caulking used in most buildings. Study of air infiltration and caulking this windows in several ways such as energy, indoor air quality, thermal comfort and pollution entering in the building is important. In this study consists of two parts, first experimentally investigated the airtight performance of various window gaskets. For this purpose, using 8 different types of gaskets and simulate modern window gap, air infiltration rates measured at different pressure differences. The results show that the airtight performance of various gaskets are different. Also fitted the experimental results by power low equation, and relations and coefficients for calculate air infiltration rate of modern windows (sealed windows), respectively. In the second section due to the very low air infiltration rate of the experimental results, indoor air quality assessed by numerical modeling methods. In the sample model, air infiltration of modern windows as ventilation and human breathing as a source of CO2 simulated. Indoor air quality is weighed by the CO2 concentration in the interior space. The results show that the air infiltration of window gaps to ensure air quality during the 8 hours is not enough. Then, assuming uniform distribution of CO2 in the sample space, and solve the transfer species equation for the problem situation, analytical equation for evaluating indoor air quality were achieved. Analytical results matches on numerical simulation results exactly. The results of this study can be very useful for HVAC engineers.

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Estimating indoor air pollutants to ensure the air quality is very important. In this study, a conventional residential space is numerically simulated in order to investigate the behavior of pollutants. Using the numerical results and the experimental results of other references, proposed the analytical relation to estimate the concentration of CO2 in term of factors such as CO2 produced by breathing residents or combustion equipment, the volume of space and ventilation rate. The results of the analytical relation are full compliance with experimental and numerical results and it can be used to estimate indoor air quality. Proposed relation can be used in all the same cases.