MVHR extract ventilation rates

[Fed]

Hello,

I am in the process of modelling a high energy performance building with electric heaters and MVHR in each room in a simplified way (ie without using ApacheHVAC). I would like to check if my proposed approach based on what I read on relevant topics in the forum and IES manuals is appropriate.

System level (Apache Systems):
Selected central heating using water - radiator as HVAC system to be able to compute the heat recovery seasonal efficiency, using 'centralised balanced A/C or mech vent system' as the air supply system, and 'AEV and any zone-level SFP' as auxiliary energy method.

Template (Tabular Building Template Manager):
Set flow rate (outside air min flow rate), 'ON' continuously

Room level (Tabular Room Data):
Set supply specific fan power, calculated as the total supply and extract fan power divided by the supply flow rate (according to a FAQ available in the IES KnowledgeBase portal).

I am not clear how the mechanical ventilation extract rates can be defined? I understand from the above mentioned FAQ that the local mechanical exhaust at room level is used to include for exhaust from toilets, changing rooms etc. rather than to be used for general extract.

Thanks.