At least as far as I can tell, the 13% is for all buildings, not just residential. From the article:

Buildings make up another major source of emissions. Greenhouse gas emissions from buildings accounted for 13 per cent of Canada's total emissions in 2021

But the larger point is that even if this exemption were for the entire 13%, as recent polling has the Conservatives winning a majority I'd say any of that exemption is worth keeping the Conservatives out of power, if only so the climate has a fighting chance. That exemption would hurt a lot the environment a lot less than the "drill baby drill" motto of the Conservative party.