Achieving a good level of airtightness

Careful design, specification, quality control during construction and performance testing the building will achieve an airtight building envelope.

Design
The building form, position and types of opening, interaction of the structure and airtight layer all effect the air leakage performance.

An appropriate airtightness specification must be selected.

The line of the airtight barrier should be identified as soon as possible allowing examination of details at openings and junctions in the envelope.

Specification
The components and systems that make up the external envelope such as curtain walling, windows, cladding etc must achieve at least the specified level of airtightness set for the building. Responsibilities for dealing with coordination at junctions should be clearly spelled out.

Construction
All supervisory staff and subcontractors should be adequately briefed on the importance of maintaining the airtight barrier, quality control and reproduction of the designers details.

Testing the building when the external envelope is complete will confirm the performance of the building.