Infiltration - based on component area or not?
Posted: Thu Apr 13, 2017 8:56 am -1100
Hi all,
the WUFI pro 6 manual states: "However, practical measurements usually determine the total air flow through the whole building envelope, not the air flow through the building component under investigation. Based on empirical determinations of infiltrated amounts of water it is assumed here that the mean flow density through the standard cross-section of a component is about a factor 15 smaller than the mean flow density through the whole building envelope (comprising also windows, doors, joints between building components and other leaks). The following values are proposed as typical for different airtightness classes (cf. [1]):
Airtightness class Air flow through envelope Air flow through component
q50 [m³/hm²] q50,comp [m³/hm²]
A 1.0 0.07
B 3.0 0.20
C 5.0 0.33
"
Does this mean that the "air flow through envelope" which is the number that is shown in the software is the total infiltration/exfiltration in the building?
I'm asking because I want to plug in a used-defined value, but I want to know how WUFI calculates the amount going through the wall section I'm modelling. Initially I thought it would just put the entire value (so 1.0, 2.0, or 3.0 for class A,B,C) in the wall section, but it sounds like WUFI actually divides the input by 15. Is that correct?
Is the user-defined field meant for people to just enter the blower door test value divided by the entire building envelope area and call it a day?
Thanks for any help.
the WUFI pro 6 manual states: "However, practical measurements usually determine the total air flow through the whole building envelope, not the air flow through the building component under investigation. Based on empirical determinations of infiltrated amounts of water it is assumed here that the mean flow density through the standard cross-section of a component is about a factor 15 smaller than the mean flow density through the whole building envelope (comprising also windows, doors, joints between building components and other leaks). The following values are proposed as typical for different airtightness classes (cf. [1]):
Airtightness class Air flow through envelope Air flow through component
q50 [m³/hm²] q50,comp [m³/hm²]
A 1.0 0.07
B 3.0 0.20
C 5.0 0.33
"
Does this mean that the "air flow through envelope" which is the number that is shown in the software is the total infiltration/exfiltration in the building?
I'm asking because I want to plug in a used-defined value, but I want to know how WUFI calculates the amount going through the wall section I'm modelling. Initially I thought it would just put the entire value (so 1.0, 2.0, or 3.0 for class A,B,C) in the wall section, but it sounds like WUFI actually divides the input by 15. Is that correct?
Is the user-defined field meant for people to just enter the blower door test value divided by the entire building envelope area and call it a day?
Thanks for any help.