Method and system for testing airtightness of a building envelope

A non-transitory computer readable medium with program instructions for testing airtightness of a building envelope by:

• providing an air flow generator in a duct through the building envelope, wherein the air flow generator is switchable between at least two different flow rates;
• providing a differential pressure transducer configured to measure a relative building pressure between a building pressure at the inside of the building envelope, and a reference pressure of a pressure container that is coupled to the differential pressure transducer;
• repeatedly switching the air flow generator between a first flow rate and a second flow rate for modulating the building pressure as a function of time between respective equilibrium pressure values at the first flow rate and the second flow rate;
• recording the relative building pressure as a function of time;
• and
• calculating a pressure modulation amplitude of a time dependent measured value of the relative building pressure for providing a measure of the airtightness of the building envelope
• wherein the program instructions, when executed on a computer, cause the computer to carry out a method comprising:
• receiving measurement values indicative of a modulated relative building pressure as a function of time;
• calculating a pressure modulation amplitude of the time dependent relative building pressure;
• and
• outputting a measure of the airtightness based on the pressure modulation amplitude.

A system for testing airtightness of a building envelope, the system comprising:

• a differential pressure transducer configured to measure a relative building pressure as a function of time between:
• a building pressure at the inside of the building envelope, and
• a reference pressure of a pressure container that is coupled to the differential pressure transducer;
• a non-transitory computer-readable memory configured to store the recorded relative building pressures and computer-executable instructions;
• and
• a processor configured to execute the computer-executable instructions to perform a method comprising:
• reading the stored relative building pressure from the non-transitory memory;
• calculating a pressure modulation amplitude of the time dependent relative building pressure;
• and
• output outputting a measure of the airtightness based on the pressure modulation amplitude.