A new alteration or addition/extension to an existing residential home must show it meets the energy efficiency requirements of the National Construction Code (NCC). This can be achieved by completing a ‘Deemed-To-Satisfy’ assessment report and submitting it with your building permit application.
The requirement can also be met by having two NatHERS software energy ratings done: one on the existing dwelling, as is; and one for the dwelling with the alterations. This will ascertain the appropriate star rating your alteration or addition needs to achieve to satisfy requirements.