In this paper a new methodology is presented to determine airtightness of buildings. The common method for airtightness testing is through fan pressurization with a blower door test. The new methodology also uses fan pressurization. Instead of an external fan, it uses the building fan system to pressurize the building.
The new airtightness tester device is no more than a pressure sensor, a reference vessel, communication hardware and an app. The flow rate of the ventilation system can easily be measured with an airflow meter. The fan pressurization of the building is measured relative to the pressure in the reference vessel which is the building pressure with the building ventilation system turned off. Measuring the reference pressure inside the building has the advantage that there is no need to use a building opening for an outdoor pressure measurement and pressure variations over the building envelope due to wind are averaged out.
Using the building fan system reduces the price of the measuring device and the time for an airtightness test. This makes it feasible to measure the airtightness of all buildings in a housing project instead of taking a few samples as currently is common practice in the Netherlands. Our new method allows both a one-point and a multiple-point test as described in the RESNET-380-2016 . Here we only discuss the one-point test because this method is very efficient whilst also giving adequate results.
Validation of the new method has been carried out based on airtightness tests in buildings with both the blower door test and our new method. When taking the uncertainty of both methodologies into account, both pass or fail nearly all the same buildings. Preliminary results also seem to support the notion that the new method is less affected by wind, as measurements could be done on a windy day where this was not possible with the blower door test.