As Washington State’s energy codes continue to evolve, the demand for accurate building envelope assessments in Seattle is higher than ever. Commercial buildings must now meet strict airtightness requirements to comply with the Seattle Energy Code, IECC, and ASHRAE 90.1. One of the most effective methods for confirming compliance is a whole building pressurization test. Understanding this process is essential for ensuring that your project meets required performance standards.
What a Whole Building Pressurization Test Measures
A whole building pressurization test evaluates how much air leaks through the building envelope by using calibrated fans to create a controlled pressure difference between indoors and outdoors. This form of air leakage testing provides consistent data so builders, owners, and code officials can verify whether the building meets the required airtightness level. In Seattle, this testing is needed for new construction and major renovations that must demonstrate energy efficiency and air barrier continuity.
Standards Used During Building Envelope Testing
Commercial building pressurization tests must follow recognized industry standards. ASTM E779 is the most widely referenced fan pressurization standard in Seattle, while ASTM E1827 may be used for smaller buildings or alternate testing methods. For identifying leaks before final measurement, ASTM E1186 is often used. These standards align closely with the Seattle Energy Code, IECC, and ASHRAE 90.1, all of which define acceptable leakage limits and approved compliance procedures.
How the Whole Building Test Works
The process begins by preparing the building according to test requirements. Exterior doors and windows are closed, interior doors are opened, and mechanical penetrations are sealed. Calibrated fans are then installed in selected openings to create a pressure difference—commonly 75 Pascals. Sensors record the airflow required to maintain that pressure, providing a quantitative measurement of total leakage.
Multiple pressure readings are collected and analyzed to determine the building’s leakage rate, typically expressed as cfm per square foot of envelope area. Many Seattle projects must achieve specific leakage targets to meet code. Successful air leakage testing confirms that the air barrier is functioning properly and supports better building performance, indoor comfort, and HVAC efficiency.
Diagnostic Tools Used to Locate Leaks
A key advantage of whole building pressurization testing is the ability to identify leakage points throughout the envelope. Tools such as infrared cameras, smoke pencils, and tracer smoke help pinpoint cracks, gaps, and areas where the air barrier is incomplete. Performing diagnostic air leakage testing early in construction can prevent costly fixes later and reduce the chances of failing the final test.
Why Whole Building Testing Matters in Seattle
For architects, contractors, and building owners, whole building pressurization testing is more than a code requirement—it serves as a critical quality assurance step. Buildings with low leakage rates benefit from reduced energy loss, improved HVAC performance, better moisture control, and enhanced indoor air quality. As Seattle continues to prioritize high-performance construction, air leakage testing has become a standard practice on commercial projects of all sizes.