Determining Airtightness and Ventilation

Determining Airtightness

Airtightness measures how well a building's envelope prevents air infiltration and exfiltration. Evaluating airtightness helps identify areas of potential energy loss and moisture intrusion. The airtightness of a building can be determined using several methods:

• Blower Door Test: A fan is installed in an exterior doorway to pressurize or depressurize the building. The amount of air leakage is measured and expressed as air changes per hour (ACH).
• Infrared Thermography: Thermal imaging cameras can detect areas of air leakage by identifying temperature differences between the interior and exterior of the building envelope.
• Smoke Pencils or Smoke Generators: Smoke is introduced into the building to visualize air movement patterns. Areas of leakage can be identified by observing where the smoke escapes or infiltrates.

Determining Ventilation

Proper ventilation is crucial for indoor air quality and moisture control. Evaluating ventilation assesses the ability of a building to exchange stale indoor air with fresh outdoor air. Ventilation rates can be measured using the following methods:

• Tracer Gas Test: A non-toxic tracer gas is released into the building. The decay rate of the tracer gas concentration is measured to determine the ventilation rate.
• Ventilation Rate Monitors: These devices measure the pressure difference between the interior and exterior of the building and calculate the ventilation rate based on the airflow through the building envelope.
• Occupant Surveys: Occupants can provide subjective assessments of ventilation adequacy through questionnaires or interviews.

By understanding airtightness and ventilation, building professionals can identify and address issues that may compromise energy efficiency, indoor air quality, and overall building performance.