Many simplified models have been developed and are used around the world to estimate the infiltration rate for Energy Performance (EP) calculations, with different levels of accuracy, as described below. For example, the wind velocity can be estimated hourly, monthly or annually; based on the local climate or fixed estimated values; with or without taking into account shielding factors; etc.

AIVC's Ventilation Information Paper #46 aims to explain these simplified models and give some examples of methodologies applied in various countries.

Read the original source.