The standardised leakage area (SLA) is a metric used to quantify the airtightness or air leakage of a building or building component. It represents the equivalent area of all the leaks in a building that would allow the same airflow rate under a standard pressure difference.
SLA is typically expressed in square meters or square inches and is determined through airtightness testing, such as blower door tests. During the test, the airflow rate required to maintain a specific pressure difference is measured, and the SLA is calculated based on this airflow rate and the standard pressure difference.
The SLA value provides a standardised measure that allows for the comparison of airtightness levels across different buildings or components. It helps evaluate the effectiveness of air sealing measures, assess compliance with energy codes or standards, and identify areas for improvement in terms of airtightness and energy efficiency.
By reducing the SLA, building owners and professionals can enhance the energy efficiency, minimise heating and cooling loads, and improve indoor comfort. This can be achieved through the implementation of air sealing measures, such as sealing gaps, cracks, joints, and penetrations, and ensuring the integrity of the building envelope.
The SLA is an important parameter in energy performance assessments, energy rating systems, and building certifications. It provides valuable information for building professionals, energy auditors, and designers to optimise the airtightness and overall energy performance of buildings.