Case study: commercial office

1 Bligh Street, Sydney

Bligh Street, Sydney, was one of the first specifications with phenolic foam. The client felt there was a limitation on space and believed saving 20mm was worth the premium.


The original design had used bulk fibre to reduce the noise, but the chill beam system would have lead to condensation dripping on the workstations.


Using a non-porous insulation with some acoustic treatment was a compromise.


At that stage, our PIR supplier didn’t assure us that PIR would work with acoustic fibre to reduce the noise.

The phenolic manufacturer confidently said it was a closed cell, thin, high-performance insulation. In retrospect, we would have stayed with PIR. Polyiso has less water absorption and pH neutral according to DOW research.