Last week, Ms. Lena Navarro Ortiz and her team from the district of Ansbach were guests at Campus Feuchtwangen of Ansbach University of Applied Sciences. Together with Dipl.-Ing. Oliver Abel, the campus’s laboratory engineer, she took photos for the “Energiehäppchen (Energy bites)” series and explained the importance of the so-called blower door test. This procedure is used to check the tightness of the building envelope – a decisive factor for energy efficiency and the value retention of buildings.

“An airtight building is particularly important for energy efficiency. If cold air enters a house unnoticed or warm air escapes, heating costs increase. Similarly, in summer, a leaky building structure allows heat from outside to enter the building, which means that the cooling system has to run at full speed. A well-sealed house therefore saves money and ensures a comfortable room temperature,” explains Oliver Abel. “Draughts and cold corners are a thing of the past if everything is well sealed.”

Another advantage: airtightness also keeps moisture out. “Moisture in the building fabric is dangerous. It can cause mold and attack the walls in the long term,” says Navarro. A tightly sealed house therefore not only protects against high heating costs, but also against damage caused by moisture.

In the blower door test, all windows and doors are closed tightly before a special blower is installed airtight in a doorway using a clamping frame.
This device creates a slight negative pressure in the building, which helps to detect leaks. “The blower creates a pressure difference, i.e. a negative pressure of 50 pascals in the building,” explains Abel. “Leaks can then be found quickly, for example at windows, doors or at junctions between walls and roof. Devices such as smoke sticks are often used to make the leaks more visible.” This method makes it possible to determine exactly where heat and energy are being lost. “Depending on the size of the leak, this can be a lot of energy, which then has to be compensated for by the heating or air conditioning system,” Abel continues.

The blower door test is particularly important for new builds or energy-efficient renovated buildings to ensure that all building specifications are met. “A blower door measurement during construction helps to avoid serious structural damage right from the start,” emphasizes Navarro. The test can also be useful for older buildings to detect leaks, reduce heating costs and protect the building in the long term.

“The test is not rocket science,” says Abel with a grin. “It’s simply an effective way to quickly see where there’s a draught – and that’s ultimately in everyone’s interest: lower heating costs, fewer draughts, more living comfort.”