What is the Thermal Envelope?

The thermal envelope is the building fabric that surrounds the habitable space of any building.  It ensures that energy is not lost through that building structure, keeping the users of that building warm in winter, and cool in summer.

There is a definition of the thermal envelope in our New Zealand Standards:

NZS 4218:2009 Thermal insulation – Housing and small buildings defines the thermal envelope as the border – a wall, floor or ceiling/roof – between a conditioned space and a nonconditioned external space.

The “conditioned space” is the area where humans live or work.  Conditioned spaces are habitable spaces such as living rooms, bedrooms, bathrooms, kitchens and other rooms in the building likely to require heating or cooling.

The”non-conditioned pace” is the outside of the building, or an area like a garage which is not heated/cooled.

This BRANZ Bulletin provides a good basic outline of the thermal envelope HERE.