What is a common method used to identify leaks in a building's ventilation system?

• A. Thermographic inspection
• B. CO2 monitoring
• C. Blower door test
• D. Tracer smoke test

Answer: (D)

Identifying leaks in a building’s ventilation system is all about showing where air is moving out of or into the ductwork. A tracer smoke test does this directly: a smoke generator releases visible, harmless smoke into the ventilation system, and as the system runs, the smoke follows the air flow. Whenever there are leaks at joints, seams, or damaged sections, the smoke leaks out and leaves clear trails. Those visible smoke paths make it easy to pinpoint exact leak locations and assess how extensive the leakage is, even in complex or hard-to-reach ducts. This method works well under normal operating conditions and can be used with different pressure levels to reveal leaks that might not be obvious otherwise.

Other methods have their uses but don’t target leaks in the ventilation paths as precisely. Thermographic inspection looks for temperature differences and can indicate where air is moving, but it may miss small leaks or ducts hidden from view. CO2 monitoring assesses ventilation effectiveness and air quality rather than locating leak points. A blower door test measures overall building airtightness, not the specific leaks in the ventilation duct network. Tracer smoke provides the most direct visualization of leakage paths in the system.