Air volume design - is floor-by-floor balancing necessary?

Hello everyone,

is there any reason or deeper meaning behind planning the volume flows per floor so that the sum of the supply and exhaust air volume flows equals zero?

Background: I have a plan from a manufacturer who always plans the floor sums to zero. In addition, I have a manufacturer-independent plan from [TZWL], where this is not the case.

When I ask both planners, [TZWL] says "No, there is no need for that," whereas the manufacturer’s planner thinks it is advantageous if the floor sums cancel out.

I am grateful for any contribution that sheds some light on this.

Thank you very much and best regards!

If you do not want a draft between the floors through the stairwell, the air supply and exhaust should be roughly equal. In our case, this was also planned very meticulously.

Can you actually feel a draft with a difference of 30cbm/h between ground floor and upper floor through a stairwell (ceiling opening area approx. 6 sqm)? Shouldn't it then also be drafty in every overflow area (hallway) within one floor with that argument?! [emoji848]

As a rule, every hallway is a transfer area (supply air in the bedroom, exhaust air in the bathroom, for example). With a sufficiently open construction between the ground floor and the upper floor, one can IMHO mentally describe the hallways and the staircase as a single large transfer area.

Therefore: In a typical single-family house, where the hallway on the upper floor is openly connected to the hallway on the ground floor via the staircase, the volume flows do not need to be balanced by floor.