Last week we entered the project information. This week we start actually building an assembly the easy way - at our computer with our coffee and croissant close by!
First, a bit of housekeeping. WUFI will default to SI measurements. If you want to model and test in IP, be sure to change that by selecting “Unit System” from the “Options” pull down menu. Be sure to click the “Use as Default” box if you desire.
Let’s open the component section of the project and look at the starting screen for designing an assembly. You will notice that there is some information there, but it is like looking at a lump of clay before the artist does something with it. “That’s a mighty fine lump of clay you got there!”
So, let’s pick a material for our lump of clay to be. Clicking on the “Material Database” button brings up a new window. It starts with the Fraunhofer Database of materials, and unless you are working with those, you will want to be in the generic or the North America database. Note, that as a user of the free version of WUFI you are unable to add materials or change much of their information. This is because you should purchase the full version if you will be modeling projects commercially so the fine minds at Fraunhofer IBP can continue to bring you the gold standard of moisture migration software instead of asking if you want fries with that sandwich!
I went into the North America database and chose cement board for my starting material. WUFI works with the materials set up to have the exterior on the left side of the assembly, and the interior on the right. When it adds new materials, it adds them to the right so I always build my assemblies from left to right, though I could click and drag a material to a different position in the assembly if I decide it needs to be located somewhere else.
You will notice that now there are two grid sections under the initial lump of clay. It may look like it is still a lump of clay, but it is actually now considered cement board and that material just happens to have the same default grey color. (You can’t change material colors in the free version, but you can in the Pro version.) Once you have defined what material your layer is you will see the grids. If you add a new layer and have not yet defined what material it is the grids will disappear. You only need to define the material for each layer and the grids will be there.
The grid areas serve two purposes. The one on the top represents the entire assembly and will show camera locations, water sources, and heat sinks associated with each material. The bottom grid area is specific to the selected material you are looking at. You can set a camera position by clicking on a segment of the top row and then be able to see results related to that camera when you are done. If you forget to set a camera, or don’t realize you will need one, you can still go back and look at data like that after a calculation, it’s just convenient to have it done from the get go if you know that you will need it.
Adding new layers is as easy as clicking a button. Need two of the layers of the same material? Duplicate the selected material with the click of a button. You are able to change the thickness of your materials but you must NEVER change the thickness of your membranes. This is because they have been given special properties so that they can be seen in relation to the other materials. If you have a foot of concrete and a membrane next to it then another foot of some other material, you would never see the membrane you entered even though for calculation purposes the computer would know it would be there. Just so that you know as much as the computer, the designers gave you magic magnifying glasses when it comes to membranes and you can see that they are there – just don’t change the thickness of the membrane because the magic won’t play nicely with your calculations if you do.
I went ahead and added the rest of the materials I want in my assembly for this case. I need to go back and change the thickness of the fiberglass because the default measurement is for a 2x4 wall. Be sure you have the thicknesses of the materials listed correctly so that you get as good of a model as possible. As with anything – garbage in means garbage out.
Up Next – let’s Sink our teeth into the Source of the problem.