ᐅ Air Volume Design – Is Floor-by-Floor Balancing Necessary?

Hello everyone,

Is there any particular reason or underlying purpose for planning the volume flows per floor so that the sum of the supply and exhaust air volumes equals zero?

Background: I have a plan from a manufacturer who always designs the floor sums to be zero. In addition, I have an independent plan from TZWL where this is not the case.

When I ask both planners, TZWL says, "No, there is no necessity for that," while the manufacturer’s planner believes it is advantageous if the floor sums balance out.

I would appreciate any input that sheds light on this.

Thank you very much and best regards!

If you want to avoid air drafts between floors through the stairwell, the air supply and exhaust should be roughly balanced. In our case, this was planned very carefully as well.

Do you actually feel any draft with a 30 m³/h (cubic meters per hour) difference between the ground floor and the upper floor through a stairwell (ceiling opening area about 6 m² (65 sq ft))? By that logic, shouldn’t there be a draft in every air transfer area (hallway) on the same floor as well?! [emoji848]

As a general rule, every hallway serves as an overflow area (for example, supply air in the bedroom, exhaust air in the bathroom). With a sufficiently open design between the ground floor and upper floor, one can, in my opinion, consider the hallways and staircase as a single large overflow 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 air volume flows do not need to be balanced separately on each floor.