Description

Recent BRANZ research into the airtightness of apartment buildings has prompted a shift in thinking around airtightness and ventilation. BRANZ now recommends that residential buildings are mechanically ventilated and are built to an airtightness target.

The airtightness of a building is a measure of how much air flows between indoors and outdoors through the structure itself – in other words, how big the holes are in the structure.

Airtightness is a key aspect of a building’s performance, affecting the energy efficiency, thermal comfort and indoor air quality. However, airtightness is only mentioned indirectly in the New Zealand Building Code, and there is no requirement to meet a particular target level of airtightness.

Scope

This article includes:

• BRANZ tested a range of apartments
• Airtightness similar to new standalone houses
• Airtightness ranged from 1.9–12.6 ach
• Many homes underventilated
• Aim for 3 ach @ 50 Pa
• Move to mechanical ventilation
• Only small improvement needed
• Resources to help achieve airtightness
• Dealing with air leakage
• A different approach