Plus 2.X:First Steps

Example Case

This short example guides you step by step how to input and calculate a case. To create and compute a new case, please perform the 13 following steps.

STEP one: Information and setting of Framework Conditions

Press the “New Project” button in the Menu Bar and define a name for your project by clicking on “Case 1” in the Project Explorer. Additionally, you can enter remarks. More important is the setting of a Start and End Value as well as a suitable calculation time step like shown below in Figure 1. Furthermore, it is possible to check the entry “Only thermal calculation” (green box). Using this setting the coupled heat and moisture transport processes in the assemblies will be neglected. Only the energy transport will be considered. This will accelerate the calculation process but causes unreasonable results especially for the moisture balance as hygric interaction with assemblies is neglected. The humidity conditions inside the assemblies are not available.

STEP two : Definition of the climatic conditons

Basically, the climatic parameters, i.e. weather, influencing the simulated building can be defined here. If you want to use one of the predefined climate conditions, follow steps a) and b) shown in the picture below.

After hitting the “Browse” button another window opens (Figure 3) and the desired climate can be chosen from predefined locations by double-clicking on it.

For advanced users: It is also possible to define own climate conditions or to import own climate files. For further information, look at the special chapter.

As long as your building does not float in the air, for whatever reason, it is necessary to define at least one additional climate to give reasonable boundary conditions for the inert behavior of soil. This can be done using the “Optional Climates” tab. For the soil temperature it is accurate to select a sine curve that has its peak at about two months later than summer solstice, i.e. at the end of August / in early September in the northern hemisphere. Depending on local conditions, the amplitude of the sine curve can be modified due to the annual fluctuation of the temperature curves. This fluctuation is the difference of the mean maximum temperature of soil in warm seasons and the mean minimum temperature of soil in cold seasons. For continental climates like Siberia this amplitude may be high (high temperatures in summer, very cool winter), for maritime climate systems it is rather low. Furthermore, the mean temperature must be set. This can be approximated using the annual average air temperature. In this example we assume the climate of Holzkirchen, the WUFI’s origin with moderate continental climate. How this can be entered in WUFI®Plus can be seen in Figure 4 on the next page.

[Bild:14_soilclimate.png|4:Setting of an optional climate]

At first click at the “New” button to create a new optional climate. Then choose the sine curve and rename it to soil Climate for example. In the next step choose “User Defined Sine Curve Parameter” and input following data for the temperature:

Mean Value (°C)	6
Amplitude (°C)	5,5

For relative humidity a constant mean value of 99% is adequate.

STEP three: Generate Building Geometry

For generating of the geometry, there are two basic options. Rather simple buildings or space can be created using the automatic building wizard. This tool generates a building with predefined floor plan, roof and foundation selections. Here we assume a simple case with one heated slab-on-ground zone and an inclined unheated attic. Figure 5 indicates the steps to generate a simple standalone building. There is also a possibility of defining the orientation of the main facade of the building as highlighted in Figure 15 at the bottom. If, however, a more complex building is requested, it can be created using vertices. For further information consult the online - help.

[Bild:15_buildingwizard.png|5:Using the automatic building wizard]

Windows are created by clicking on the desired component in the “Visualization Box” and following the blue highlighted arrow in Figure 16. The “Component Openings” window pops up. By clicking on the button highlighted by the red arrow in Figure 16, new windows can be created. In this example, one window is implemented on one outer wall (surface with normal vector in y – direction).

The X’ – axis is the orientation of the window in horizontal direction and the Y’ – axis in vertical direction. To create our window, please insert:

X´(m)	1
Y´(m)	0,9
Width (m)	1,2
Height (m)	1,5

Checking the Caption Bar of the “Component Openings” window defines whether the wall is viewed from inside or outside.

The new window will be shown under Visualized Components. So the windows and openings created will appear in the navigation tree and can be edited as usual.

[Bild:16_windows.png|6:Generating windows]

For advanced users: It is also possible to generate openings by using the 3D Edit tool or by defining own points. Check the online - help for further information.

STEP four: Definition of the Components.

Primarily, a component is a surface of the building. It may be the roof, the base plate or vertical walls. As the composition of our vertical walls is mostly the same, those can be summarized as one component. This is predefined in WUFI®Plus. To change this, click on the aimed component in the Visualization Box. Afterwards, right click on this component, choose “Ungroup” and follow the instructions in accordance with your aimed modification. The “General” tab outlines basic data of a component and enables titling of components. Especially in case of numerous components, this is important to evaluate results.

We start with Component 1, the Bottom Plate according to the steps shown in Figure 7. Choose the component you want to edit in the Project Explorer [1], next assemblies can be allocated to a component in the “Assembly” tab [2]. The Project construction list [3] shows all constructions used in a project. The highlighted one is applied to the respective component. As no constructions were assigned so far, the list is empty for one plain construction, which must be chosen. As there is no predefined geometry for the bottom plate, you have to define one, this is done by clicking the “Edit” button [4] which opens the “Edit Assembly” window [5]

[Bild:17_component1.png|7:Editing an assembly]

At first you have to name the Assembly. In our example it is called “Bottom Plate”. Then, by clicking on “New” you can import different layers of the construction from the database (See Figure 8). Beginning on the outside for our example the layers are: { |1 |XPS Surface Skin (heat cond.: 0,03 W/mK) |0,01m |- |2 |XPS Core (heat cond.: 0,03 W/mK) |0,14m |- |3 |XPS Surface Skin (heat cond.: 0,03 W/mK) |0,01m |- |4 |Concrete, w/c=0,5 |0,26m |- |5 |PVC Roof Membrane |0,001m |- |6 |EPS (heat cond.:0,04 W/mK – density: 30kg/m³) |0,1 |- |7 |Gypsum Fiberboard |0,025m |}

[Bild:18_editassembly.png|8:Creation of an assembly]

Now you have created a new assembly called “Bottom Plate”. The bottom plate is not surrounded by air, so you have to choose the optional soil climate created in step 3.2.2. This works like shown in the figure below.

[Bild:19_bottomplateclimate.png|9:Assigning an optional climate]

Second is Component 2, the roof, which gets an assembly assigned to it according to Figure 10. Again choose it in the Project Explorer [1], open the “Assemblies” tab [2]. Now a “New” construction needs to be added to the Construction List [3]. There is the possibility to choose predefined assemblies by clicking on “Select from database” [4]. Here Flat Roof #1 is chosen [5].

[Bild:20_flatroof1.png|10:Assigning an assembly for the roof]

Next proceed according to the roof for Component 3, the vertical walls and choose “Lightweight timber framed wall” from the database.

Besides the “Assembly” there are various other aspects concerning the vertical walls that need to be specified. First of all in the “Surface” section the “Thermal” subsection offers possibilities to change heat transfer resistance, absorption and emission factor according to the material of the outer surface, a general shading factor of the outer surface and solar gain. Furthermore the “Moisture” subsection allows specifying Sd-Values of the surface and inputting additional information about rain afflicting the building. There is also a “Climate on outer surface” subsection where the climatic terms of outer surface can be adjusted (see “Bottom Plate”). Next, there is a “Initial Conditions” section where boundary conditions of the project can be altered. For example the initial relative humidity could be increased to model drying out the building. In the “Report: Data & Results” section you could check “Retain calculation results” for hygrothermal performance assessment.

Assinging a window type to the windows from the database works similar, please choose “Uncoated double glazing” for your window.

Figure 11 illustrates the possibility of changing specific window parameters. The U parameter is the heat transfer coefficient. The frame factor enables description of opaque surfaces of the window. In effect, heat gains by solar radiation depend on the angle of incidence. In order to simulate this, the Solar Heat Gain Coefficient (SHGC) can be used. It can be set in general and with reference to the changing incident angle of solar radiation. There are appropriate predefined values, however they can be adjusted. The Emissivity of external surface is a value similar to the two previous items mentioned above. It expresses the amount of emitted radiation from the outer surface.

[Bild:21_windowparameters.png|11:Edit window parameters]

For advanced users: If a required material is not available in the database, it is possible to define a new material. Normally these parameters can be found in technical data sheets, necessary for this definition are:

• Bulk density [kg/m³]
• Porosity [m³/m³]
• Specific heat capacity [J/(kg K)]
• Thermal conductivity [W/ (m K)]
• Water vapor resistance factor [-]

Also user defined assemblies can be saved in the database, this is reasonable, if you want to reuse assemblies as you don’t have to define them using the “Edit” button (like you did defining the bottom plate) each time but can easily select it from the database.

STEP five: Definition of “Not visualized Components”

These components may be partition walls that do not separate inner climatic zones but have influence on the indoor climate as they can have heat accumulation effects due to their mass. First, a new component is established, then its surface is assigned with 25,2 m²

[Bild:22_notvisualized.png|12:Definition of not visualized components]

Afterwards the assembly of this “Interior Wall” is defined. The proceeding is similar to the one of the bottom plate. The Layers are:

1	Gypsum Board	0,02
2	Solid Brick ZA	0,08
3	Gypsum Board	0,02

STEP six: Setting of Inner Loads (Occupancy Schedule)

Inner loads like working people or computer produce heat, carbon dioxide and moisture. When and for how long inner loads occur is determined here. For our example, it is assumed that there are three adult people working at a desk from Monday till Friday between 8 am and 5 pm. In the following, the verification of this is explained using the steps indicated in Figure 13. Therefore, a new period must be defined and the checks for Saturday and Sunday must be removed ([2] and [3]). Note that first of all the lowest row is the primary one, and for time periods not defined by it (Saturdays and Sundays) the upper one is relevant. Afterwards, the day profile for this new period must be supplemented by two entries [4]. The time is entered in 24 – hour units [5]. For our time interval beginning at 8 am, the predefined calculator is used [6] and the values for an “adult, sitting and working person” are loaded using the button “OK” [7]. The count has to be adjusted to the value three [8]. After confirming this, the numbers shown in [9] will appear on screen.

[Bild:23_innerloads.png|Setting occupancy periods]

For advanced users: Another option for getting inner loads is to load an own schedule for supported file types. Please consult the online - help where this issue is dealt with in an own tutorial.

STEP seven : Defining Design inner climate Conditions

Step seven is related to step six. In this step you have to verify the kind of heating/cooling and the ventilation system. Preliminary it is important to know that for indoor climate conditions two basic requirements are necessary:

• a schedule to control working hours of heating, cooling, de-/humidification or ventilation system and
• a definition of capacities of these systems.

In this step, the schedules for our design conditions (the conditions to be maintained by the HVAC equipment) are defined. The indoor atmospheric conditions should conform to a certain range of temperature and relative humidity. Limits for those parameters can be set in this section. According to a healthy room temperature, in this example we use the following parameters:

heating
0 hours	17°C
8 hours (working time)	21°C
16 hours (night)	17°C
cooling
0 hours	27°C
8 hours (working time)	24°C
16 hours (night)	27°C

During night and on weekends, this interval can be set more widely with a range between 17 and 27 degree Celsius. For implementation in WUFI®plus follow the procedure (red numbers) depicted in Figure 14.

[Bild:24_designconditions.png|Setting of inner climate conditions]

The next step is similar to the last one. There are three subsections in the “Ventilation” section. “Natural” means air interchange through building leaks. The leakage rate and the day profile should be inserted. During the working time the leakage rate is higher because of manual window ventilation. If there is a “Mechanical” ventilation system in the building, proceed like shown in Figure 15. At first a new schedule for working days has to be created, but note, that if a mechanical ventilation is established, do not forget to assign sufficient capacities in the HVAC menu item later on.

[Bild:25_designconditions2.png|Scheduling the ventilation system]

For advanced users: It is possible to consider air exchange between heated zones with different temperatures in the subsection “Interzone”. It is also possible to input values for “Relative Humidity” and “Max. CO2 Concentration”