A building envelope is not a building envelope.

Confused? I was. Unfortunately, there are two definitions of the term ‘building envelope.’

They are:

  1. Design parameter definition.
  2. Building science definition.

DEFINITION 1: – Design Parameter.

Anyone involved in building design in Australia will be familiar with a designated area marked on a plan of subdivision called a ‘Building envelope.’

These building envelopes set design parameters for development on a lot, and all building works must be contained within the designated envelope.


DEFINITION 2: – Building science.

In the world of building science, we regard the ‘building envelope’ as the boundary that┬áseparates inside from outside, conditioned space from unconditioned space. We use our red pen at building design stage to help designate this area.┬áThe Water, Air, Vapour and Thermal control layers apply to this line. Click here for the WAVT post. Click here for Building envelope with a red pen post.



LESSON FOR STUDENTS: If you attend building science training and the instructor tells you to pick up a red pen and define the building envelope, they are referring to definition 2. Many instructors are fron North America or Europe and they are not familiar with definition 1.

LESSON FOR INSTRUCTORS: If you are teaching building science to Australian designers and builders, don’t be surprised if they draw a big red rectangle around everything when you ask them to define the building envelope. They are thinking of definition 1.