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New build oak framed family home achieves below Passivhaus air tightness levels

Here's how this new build oak framed family home in Herefordshire achieved below Passivhaus air tightness levels.





Air Leakage Reduction


Our clients, David and Diane, chose to design their dream oak framed home with our teams here at Oakwrights. As they are based in New Zealand, they needed their project to be fully managed from start to finish. So they opted for Oakwrights’ turnkey project management service, whereby I oversaw every stage of their build: from groundworks, first fix installation, and second fix fittings, right through to helping them finalise paint colours and other finishing touches.


Their challenge

David and Diane wanted to design and construct the most low-carbon, cost-effective and healthy home that was feasible within their budget. To achieve this, we began by incorporating a Mechanical Ventilation and Heat Recovery (MVHR) system and an Air Source Heat Pump (ASHP) into their home building plans. To support these, David and Diane also decided to insulate their home with Oakwrights’ WrightWall and WrightRoof encapsulation system.

Choosing AeroBarrier

To make the best use of all our clients’ high-value additions, we take great care in ensuring our oak framed buildings are high performance in every element we specify. In addition to our two encapsulation system offerings, we can also incorporate modern face glazing into our clients’ designs to maintain an air-tight, sustainable security blanket for their builds.

When David and Diane heard about AeroBarrier, they were drawn to how the system would ensure that all their high-performance additions could work to their greatest efficiency and in unison, guarantee a highly energy efficient home from the outset.

Exceeding air tightness requirements

The AeroBarrierUK team arrived at David and Diane’s site in the morning and started to prepare their building – some initial taping work around windows was undertaken, whilst the team also protected the portions of flooring that had been fitted. The team also undertook an initial manual check of common leakage points before setting up the sealing equipment. The preparation and setup stage was the longest component of the air tightness testing and air sealing session – taking around 60% of the total time on-site.

The team then did a pre-seal air tightness test which gave a result of 2.03 ACH50. This was typical for the complex building design and for Oakwrights’ closed-panel encapsulation system without a full seal or specific high-performance works. Once the air sealing process was in progress, the AeroBarrierUK team regularly monitored the progress of the seal and explained how they were periodically checking that all the stations were operating as expected. They did this until the final desired air tightness was reached.

AeroBarrier results

The final airtightness result for David and Diane’s oak framed home was 0.11 ACH50 – on par with the tightest homes in the UK! They were very pleased with the outcome and how their desired target figure was met so quickly.

For our high-performance design, we were looking to achieve low-carbon levels of air tightness, ideally below 1.0 ACH50 and hopefully below the Passivhaus standard of 0.6 ACH50. With a final test result of 0.11 ACH50, we beat this result by around six times, which the AeroBarrier system achieved on-site with us that day!

The key element for us is that AeroBarrier gives us the ability to take our high-performance building system and offer any level of air tightness that best suits our clients’ projects. There is no other system with the flexibility, repeatability, and guarantee that we can get with AeroBarrier. If we wanted to get similar results from 2 ACH50 down to Passivhaus via traditional methods, this would have taken days, if not weeks with multiple site visits, hours and costs on-site with absolutely no guarantee of reaching these levels – AeroBarrier changes all that within a day!