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Nowadays, the baseboard heating systems have attracted the attention of many HVAC engineers because of its uniform temperature distribution and low feed water temperature. Despite this, the uniformity of indoor thermal conditions can be disturbed by some parameters such as exterior walls and air infiltration from window gaps. Therefore, the main goal of this study is to investigate the effects of air infiltration from window gaps on the performance of baseboard system and occupants’ thermal conditions. For this reason, a room has been considered under the terms of “ASHRAE-140 standard/Case 600” and climatic conditions of Tehran with winter outdoor design temperature of -10C. Also, the heat power on the baseboard panel has been set as much as the average of occupants’ thermal dissatisfaction index stays within the allowable range (lower than 10%). The results show that the heating baseboard system can provide the appropriate thermal conditions for sitting occupants with average panel temperature of 43C. In spite of this, the distribution of occupants’ dissatisfaction index near the floor is not uniform. The results indicate that the air infiltration can cause to increase the thermal dissatisfaction index up to 40% in the floor region.

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Study air infiltration into the building in several ways such as energy, air quality, thermal comfort and pollution entering in the building is very important. In this context, many studies have been conducted in different countries. In our country due to the use of steel doors and windows, do independent research on the gap size and air infiltration is necessary .In this study, by practical view and in order to localize results, based on a field study, the actual dimensions of the gaps around conventional doors and windows in Iran is measured. The results of these measurements are used to simulate gaps, then with experimental study, air infiltration rate of this gaps is calculated at different pressures. In present study, after investigating the effect of different aspects of gaps on air infiltration rate, two common equations, power law and quadratic equation, in order to fitting data were compared. Results show that power law equation can adapt better to the experimental data. Coefficients of the power law equation to estimate the air infiltration rate through the gaps was presented. By analysis of the results, due to the proximity factor of the pressure difference to the number 0.5 in most of the results, it was concluded that the Bernoulli equation can be used to predict the air infiltration rate through the gaps. This equation is better compliance with laws and physical principles. Discharge coefficient of the Bernoulli equation for gaps with different dimensions are calculated.

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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.