When it comes to calculating the thermal performance of building systems, recent changes in regulations have made things a bit more complex.
The shift from NCC 2016 Section J to NCC 2019 Section J brought about significant changes in the calculation methodology. The updated guidelines now require thermal bridging, which refers to the loss of insulation caused by interruption due to framing, to be taken into account.
Let's take a lightweight clad wall system as an example, featuring a 92mm steel stud frame installed at 600mm intervals as an example. Under the previous NCC 2016 Section J, if we were to install a 90mm R2.5 Gold Wall Batt insulation product in this system, it would yield a system thermal performance rating of approximately R2.6.
However, under the new NCC 2019 Section J guidelines, the same system would have a significantly lower system thermal performance rating of around R0.85. As you can see, the change in the calculation methodology has led to vastly different results for the same system.
