The airtightness levels of a building can be measured using a fan, temporarily installed in the building envelope (a blower door) to pressurize the building. The air flow through the fan creates a uniform, static internal pressure within the building. The objective of this type of measurement is to relate the pressure difference across the envelope with the air flow rate necessary to produce it. In general, the greater the flow rate required to produce a given pressure difference, the less airtight the building will be. The fan pressurization technique is also described in many standard test methods, such as ASTM E779 - 10,[14]​ ASTM E1827 – 11,[15]​ CAN/CGSB-149.10-M86,[16]​ CAN/CGSB-149.15-96,[17]​ ISO 9972:2006 (now superseded) and EN 13829, which is now "retired" due to the updated ISO 9972:2015.

Most European countries include mandatory or recommended minimum levels of tightness in their construction regulations, with or without mandatory tests. There are several countries (e.g. United Kingdom, France, Portugal, Denmark, Ireland) where, by regulation, airtightness testing is mandatory for certain types of buildings or in the case of specific programs.[18]​.

In the United States, the 2012 IECC adopted airtightness requirements for all buildings, including mandatory testing.[19] Additionally, in May 2012, the Army Corps of Engineers issued a new Engineering and Construction Bulletin in collaboration with the Air Barrier Association of America, which outlines the Army's requirements for building airtightness and building air leak testing for new and renovation construction projects.[20] Washington was the first. state to institute air barrier requirements with a maximum material air leakage requirement and a maximum air permeability rate for the entire building with testing requirements for buildings six stories and higher.[21]​.

There are several voluntary programs that require a minimum level of airtightness for the building envelope (Passivhaus, Minergie-P, Effinergie, etc.). Historically, the Passivhaus standard, originated in 1988, was the cornerstone for the development of envelope airtightness because these types of buildings require extremely low leakage levels (n below 0.6 ach).

The airtightness levels of a building can be measured using a fan, temporarily installed in the building envelope (a blower door) to pressurize the building. The air flow through the fan creates a uniform, static internal pressure within the building. The objective of this type of measurement is to relate the pressure difference across the envelope with the air flow rate necessary to produce it. In general, the greater the flow rate required to produce a given pressure difference, the less airtight the building will be. The fan pressurization technique is also described in many standard test methods, such as ASTM E779 - 10,[14]​ ASTM E1827 – 11,[15]​ CAN/CGSB-149.10-M86,[16]​ CAN/CGSB-149.15-96,[17]​ ISO 9972:2006 (now superseded) and EN 13829, which is now "retired" due to the updated ISO 9972:2015.

Most European countries include mandatory or recommended minimum levels of tightness in their construction regulations, with or without mandatory tests. There are several countries (e.g. United Kingdom, France, Portugal, Denmark, Ireland) where, by regulation, airtightness testing is mandatory for certain types of buildings or in the case of specific programs.[18]​.

In the United States, the 2012 IECC adopted airtightness requirements for all buildings, including mandatory testing.[19] Additionally, in May 2012, the Army Corps of Engineers issued a new Engineering and Construction Bulletin in collaboration with the Air Barrier Association of America, which outlines the Army's requirements for building airtightness and building air leak testing for new and renovation construction projects.[20] Washington was the first. state to institute air barrier requirements with a maximum material air leakage requirement and a maximum air permeability rate for the entire building with testing requirements for buildings six stories and higher.[21]​.

There are several voluntary programs that require a minimum level of airtightness for the building envelope (Passivhaus, Minergie-P, Effinergie, etc.). Historically, the Passivhaus standard, originated in 1988, was the cornerstone for the development of envelope airtightness because these types of buildings require extremely low leakage levels (n below 0.6 ach).