Blower Door Test by Living Building Solutions
The method of airtight building wrap in this case is to wrap the layer on the outside face only, using the exterior face as both the weathertight and airtight layer.
The internal face of stud work can be seen bare without linings during the testing.
We’ve been working with our fantastic client Clare on her home in Normanville since September 2021.
Clare’s brief was for a comfortable, medium sized family home that would take advantage of solar passive design principles to achieve excellent year-round, thermal performance. Focusing on that brief and pairing the design with a mixture of climate responsive materials within a domestic allotment near the sea, initially we’d hoped to achieve a NatHERS rating of close to 7.5 stars. Ultimately with several tweaks during the design & documentation process the home achieved a rating of 7.8 Stars.
As a client who came to the process well researched about high performance homes, rather than just talking about it in a nominal sense, Clare was prepared to meet the challenges of obtaining tangible high performance outcomes. One of the aims was to build a home with good airtightness, hoping to achieve a building envelope that would sustain between 4-6 Air Changes per hour or ACH.
Note: 4-6 ACH is considered to be somewhat ‘easily obtainable’ with some attention to the constructed detail.
Having been briefed on the requirements and the need for attention to detail, 35 South Building Company had the framing and Proclima airtight wraps installed and ready to test by the beginning of April.
Living Building Solutions then undertook testing via the Blower Door Test. 35 South’s crew did a few last minute tweaks, taping joints and blocking up conduits; the atmosphere on site (and the air inside) was thick with anticipation. Whilst the fans spun at high speed, we waited for the results.
Thankfully, the Blower Door Test was a resounding success. At an air leakage rate of just 0.668 ACH it was only a fraction above the PassiveHaus benchmark of 0.6 ACH.
The builders, client and designer all rejoiced with the extremely high level of airtightness achieved and Clare was super happy that the mechanical contractor had convinced her to install a fully ducted Mechanical Heat Recovery Ventilation system instead of the previously quoted, smaller decentralised ones.
The inclusion of ducted MHRV is an absolute requirement in buildings this tight so that decision was serendipitous.
This method of achieving a thermally efficient building envelope is becoming increasingly popular as a way of lowering energy consumption by reducing heat loss during winter and heat gain in summer. In truth, the design contains many elements of a PassiveHaus including high performance windows and thermal insulation including slab edge insulation so it would likely get close to PassiveHaus certification.
35 South can be congratulated for their application of skill in achieving this excellent result.
With the bespoke galvanised roofing, recycled brick, polished concrete and combination of Weathertex and Fine Texture Cladding, we’re looking forward to seeing the finished form reveal itself rather soon!