How is glazing assessed in a Section J report?

The glazing thermal performance requirement is the most important part of a Section J energy report. NCC Volume 1 details the minimum requirements for glazing thermal performance in Section J, Part J4, J4D6. However, unlike NCC 2016, the new glazing performance requirements from NCC 2019 onwards are integrated with the external wall requirements. This means NCC Vol 1.0 requires the Total System U-value of wall-glazing construction not to be above a certain U-Value detailed in J4D6.

To make things easier and to try tradeoffs between glazing and wall thermal performance, the ABCB has developed the Façade calculator. Using this, the assessor can obtain the compliant thermal performance value of the project’s glazing, U-value and SHGC. These performance values will be reflected in the Section J energy report.