The intermediate air test result came in at 0.77 ACH
The building has huge quantities of sliding doors which are inherently leaky, so it was always going to be a challenge to make the opaque building fabric so good it offset this.
The Keller Minimal 4+ system is triple glazed and so more rigid than the double glazed units but still relies on simple brush seals for airtightness and was always going to be the weak point on the building (see image of smoke test)
A second air test was undertaken with the sliding doors taped which suggested the doors might account for perhaps 0.5 ACH and so excluding the sliding doors, the airtightness for the rest of the building might be around 0.3 ACH. In order to meet the Passivhaus criteria of 0.6 ACH, the rest of the building would have had to achieve an airtightness of 0.1 ACH to fully offset the sliding doors, and this was beyond the brief set by the clients and perhaps beyond what is achievable with a steel frame and with a pragmatic budget.
This is an impressive result and testament to the efforts of the whole team, and a sub 1 ACH result means the building meets the airtightness criteria for a Passivhaus Low Energy Building.
