Passivhaus Trust release new Thermal Bypass Paper

ATTMA have endorsed The Passivhaus Trust’s new Thermal Bypass Paper. The air movement across within and behind insulation increase heat loss which causes discomfort and enables mould growth is known as thermal bypass. With the correct knowledge and skills both in practice and onsite, failures in design and construction can be avoided and deliver buildings that perform as predicted.

This paper sets out the issues created with poorly installed insulation in a clear and precise way and has the potential to change the way the industry thinks about insulation and how we design to avoid thermal bypass in the future

The air tightness testing and measurement association

This Thermal Bypass Paper draws upon sound evidence base which reveals simple practical steps policymakers, developers, certifiers, designers and constructors can take to create successful high-quality, high performance and robust buildings at speed and scale to meeting climate targets.

In this paper, you’ll be able to gain new insights, build confidence and discover how you can make informed decisions that will;

  • Improve the health, well-being and energy security of building occupants and owners
  • Reduce carbon emissions and fuel poverty
  • Close performance gaps
  • Avoid costly mistakes
  • Protect the building fabric from moisture damage.
Image captured from The Passivhaus Trust Website – Source:

The paper provides a comprehensive and technical demonstration of how Passivhaus reliably closes the performance gap. If thermal performance gaps are to remain with an acceptable  tolerance, the continuous insulation should be captured on all sides by uninterrupted unbroken air and wind barriers.

You can download the paper via the Passivhaus Trust website here