Infiltration through entrance doors, vestibules, cracks and other areas have a large impact in building energy consumption. It also has a significant impact on indoor air quality. There are only a few studies about air infiltration and air tightness in the literature. The purpose of this study is to develop practical methods to measure air infiltration rates through entrance doors. We have read research articles and identify several methods in the literature. Further investigation is required to help more accurately find infraction rate, crack size and location of cracks to help reduce air infiltration, energy costs, maintain comfortable indoor conditions and lower buildings' carbon footprint.