Calculation of air infiltration in a large number of cases can give information of expected variations in yearly air change and energy consumptions. As model is used the equivalent leakage area model written in a spreadsheet computer program. For a typical Norwegian house an analysis of the influence of some parameters is made. The influence of climate is found to be small, if we compare the mean yearly air change for towns in Norway. Prediction of air infiltration is made from known variations in indoor temperature, 50 Pa pressurization air change and leakage and pressure characteristics.