An airtightness target refers to the desired or specified level of airtightness that a building or building component should achieve. It sets the benchmark for the acceptable amount of air leakage through the building envelope, ensuring that the building meets certain energy efficiency, indoor comfort, and indoor air quality standards.
The airtightness target is typically defined by building codes, energy efficiency programs, or industry standards. It is often expressed as an airflow rate or air changes per hour (ACH) value, which represents the maximum allowable air leakage per unit of building volume.
The specific airtightness target may vary depending on the type of building, its purpose, climate zone, and local regulations. For example, residential buildings may have different airtightness targets compared to commercial or industrial buildings.
Achieving the airtightness target requires careful design, construction techniques, and quality control measures. It involves the use of appropriate air barrier materials, proper sealing of joints, seams, penetrations, and transitions, and attention to detail during the construction process.
Airtightness testing, such as blower door tests, may be conducted to measure and verify the actual airtightness performance of the building. These tests help identify areas of air leakage, evaluate the effectiveness of air sealing measures, and ensure compliance with the Airtightness Target.
Meeting the airtightness target offers several benefits, including improved energy efficiency, reduced heating and cooling loads, minimised draughts and temperature variations, enhanced indoor comfort, and better control over indoor air quality by preventing the infiltration of outdoor pollutants, allergens, and moisture.