We are optimizing a 4 storey residential building for certification under LEED EBOM (it is currently under construction) . Most residential units will have to allow smoking . My understanding is that in addition to pressurization , weather stripping of apartment doors and blower tests, this also means the ducting will have to be redesigned st all air from smoking appartments must be completely exhausted outdoors and 100% fresh air only must be supplied to apartment spaces. Is my understanding correct ? The issues here are not only ducting redesign, but the energy efficiency issues of using 100% fresh air for cooling for all these spaces as this is an extremely hot climate which will completely undermine building performance in EAC1 optimize energy performance . Any other suggestions or alternatives to save the project energy efficiency performance and meet the ETS prerequisite ?