How Airtightness Testing Improves Building Performance

Air tightness

Air Tightness and Building Performance

High performing buildings are durable, comfortable, healthy and low-energy users.  An essential component of the high performance building is minimized air leakage.  Commercial air tightness testing is a quality control tool providing data for the mechanical engineer’s load and energy calculations so he/she can design the appropriate mechanical system.

As building codes become more stringent and owners desire more efficient, comfortable buildings with improved air quality and less risk of moisture damage, the industry will call for quantitative air tightness targets to verify airtight enclosures.

These targets prove useful for both new construction and retrofits.  When testing occurs early in the building or retrofit process, builders can look for problems and address them promptly. Testing early for airtightness makes sense with opportunity for energy savings, better knowledge of HVAC equipment loads and indoor air quality and condensation risk management.

Airtightness testing of larger buildings (over 929 square meters) measures the ease of air leakage through the building’s envelope by running many coordinated, simultaneous blower doors at the same time.  To prepare the building for testing, engineers seal openings including HVAC intake and exhaust grills, relief dampers and exhaust fans.

Normally, engineers take 5 to 10 airflow readings across a range of flow directions and pressure gradients.  A graph of the raw data quantifies the relationship of airflow to pressure change.  Plotting the data in logarithmic format gives a straight line useful for engineers, although in commercial construction the flow at 75 Pascals is applicable for most reporting.

The air changes per hour often found in commercial and large building air leakage reports is the volume of air leaked per hour divided by building volume.   However, with different commercial and large-scale building geometries, reporting the leakage rate at liters per second per square meter of enclosure area is technically correct and customary.  Because this method considers building size, it provides better comparisons between buildings.

When architects and engineers design for airtightness at the start and airtightness test early in construction, they routinely achieve values under 2 lps/m2@75.

Air and moisture membranes also play an important role in the performance of the building envelope.  It is important to specify the right product for the performance goals of the building.

Watch Dr. John Straube dive into the importance of airtightness and how it’s critical for maintaining a building’s performance.

Dörken delivers innovative, high-performance air and moisture barriers for commercial and residential construction sold under the DELTA® brand name. A North American manufacturer based out of Beamsville, Ontario, Dörken Systems, Inc. is a subsidiary of Ewald Dörken AG, a leading European developer and manufacturer of waterproofing and drainage products sold worldwide. Dörken is known for delivering premium products while providing educational programs and full technical support. For more information, call 1-888-4DELTA4 (433-5824) or visit