The infiltration rate applied to the building is defined by a set of equations in the 90.1 standard. This infiltration calculation is enacted by selecting the 'Whole Building Envelope' method in the dropdown dialog presented to the user. In this case the user specifies the air leakage rate of the building envelope for the proposed model and the 90.1 equations are used to calculate the space by space infiltration rate. A set rate is used for the baseline model and the baseline infiltration rates are calculated using the same methodology.
Note that the traditional way of specifying infiltration is still available by selecting the 'Space by Space' method which brings the user into space data to specify infiltration rates, however, this is not recommended as it does not use the 90.1 methodology.
