Hi,

we are modeling the HVAC system for the baseline building of a residential building. Since heating type in the proposed design will be electric, system 2 applies (1 PTHP shall be modeled for each space / thermal block). Regarding ventilation, separate fans shall be modeled in order to supply the same amount of outdoor air as in proposed design in each space.

Our doubt is related with the way these fans shall be considered in regard to heat recovery requirements. Thus:

1)  If one fan per space / thermal block is considered, baseline system does not have heat recovery;

2)  if we consider a single ventilation system for all spaces / thermal blocks, baseline system will have heat recovery (the flowrate of that ventilation unit would be higher than the threshold).

Given this, and since we could not find any evidence in the standard or users manual on how to consider these fans, which way do you think we should follow?

Regards,