WUFI Analysis Assumptions


Software: 
WUFI Pro 5.1 (1-d)

Orientation:  Each assembly was modeled facing the direction of prevailing wind-driven rain and maximum solar exposure as follows, for a vertical wall and building height up to 10m tall

Location: Vancouver (east), Edmonton (west), Toronto (east), Montreal (south-west), St. John’s (south-east)

Rain load: R1 (0), R2 (0.07 s/m) default settings

Surface Transfer Coefficients:

Exterior surface
Heat resistance: 0.0588 (m2K/W), external wall, wind dependant
Sd value: No coating
Short wave radiation absorptivity: 0.68 (red brick)
Long wave radiation emissivity: 0.90
Adhering factor of rain: 0.7 according to inclination and construction type

Interior surface
Heat resistance (m2K/W): 0.125 (External wall)
Sd value: User defined 0.3 (approximates two coats of latex paint)

Initial Conditions:

Initial moisture in component: Constant across component
Initial temperature in component: Constant across component
Initial relative humidity: 0.80
Initial temperature: 20ºC

Numerics: Each wall modeled for a simulation period of 5-9 years

Mode of calculation:
Heat transport calculation, moisture transport calculation
For thermal conductivity use temperature and moisture dependency

No hygrothermal special options

Numerical parameters
Increased accuracy
Adapted convergences

No adaptive time step control

Geometry
Cartesian

Outdoor climate: Cold year when an option, from map/file, (using analysis function for choosing worst case orientation)

Indoor climate:
User defined sine curve parameters
Temperature, mean 210C with +/- 20C (day of maximum 06/03)
Relative humidity, mean 45% with +/- 15% (day of maximum 08/16)

Note on WUFI Assumptions for Low Permeance Sheathings:
Building Codes have air barrier and rain intrusion requirements that are assumed to be complied with.  Failure to meet code requirements can result in walls that are not durable.

It is important to note that all the assemblies were simulated assuming no air leakage and no water intrusion/leakage.  As a result, the WUFI durability simulations do not consider the limited drying potential associated with the use of low permeance sheathing materials when combined with poor air barrier installation and flashing details.