WUFI

Hello,

We are starting with Wufi Plus model construction and we have some doubts.
If anyone can help us with any of this questions, we will be very grateful!

Thank you in advance,
Francisca,
Sílvia,
from Oporto.

Zones definition:
- When a component separates 2 zones, and because we can only associate a component to a specific zone, how does the program understand this? I mean, it's the same to associate that component to any of those 2 zones to simulate, or it's different, and we should associate that component to the "most important" zone to our study, for instance...? Or to the “most external” zone? The same for the orientation of the arrows defined (when it’s interior-interior element)?
- In each Zone/General, what is the difference between the Volumes: “reference”, “gross” and “net”?

External Climate:
- It’s mandatory to insert the correct year of climate data? As an example: for mistake, we insert an external climate data for the year 2012 (Jan to Dec) and start to simulate the year of 2015 on Wufi (Jan to Dec). The Wufi software simulates normally. How should we understand the calculations? The Wufi software matches data only by month/day and disregards the year inserted?

Opaque elements parameters:
Assembly/ Edit / Inner sources: What’s the meaning of “inner sources” (heat / moisture / air exchange)?

Window parameters:
- In Portugal we use the parameter "g" to define the glass thermal properties. It's reasonable to insert this property when "SHGC" is asked, both "average" and "hemispherical" and the suggested values by the program are also the same for both?

Transparent Components - Surface:
- The U value of the transparent component that we define shall already include the Rsi and Rse values? If so, why do we have the chance to change them on "general" component information?

Solar Protection Devices:
- Solar exposure: it's correct to understand this parameter as the additional solar factor given by the protection (ie, the difference between g'(glass) and g'(glass+protection)?
- Thermal resistance supplement: it's correct to understand this parameter as the difference between the U (solar protection closed) and Uw (without protections)? (using data for instance from ISO 10077-1 Annex G “Additional thermal resistance for windows with closed shutters”)
- Operation Mode: how does the program understand the "reduce overheating/cooling" mode? Reading Wufi Wiki, we understand that it "closes" the protection whenever the interior temperature is higher than the value defined on the "Design Conditions". Is this correct and the unique condition to operate the device in this option?
- How/where can we define the total/permanent closure of the protection device?

Internal loads/ occupancy:
- What value should we consider to "Metabolism"? The product of "individual metabolism per number of persons" OR the individual value of metabolism of each person (and the program sum for the total number of persons)?

- Same question for “clothing” [clo]
- How/Where shall we define the internal loads besides the human loads (lights, equipments, etc.)?
- Is there any difference between defining heating/cooling systems in “internal gains” option or in “HVAC”?

Thank you again.

Dear Francisca,
Dear Silvia,

Below, you can find the answers to your questions. You mentioned, that you start working with WUFI Plus, so I recommend you to have a look at our manual and especially the tutorial case. You can open the manual from the Help-menu (WUFI Plus version 3.0.0 or higher) or download it from our homepage (https://wufi.de/en/wp-content/uploads/s ... ual_en.pdf)

Zones definition:
- WUFI Plus always assigns the assembly to the zone that is defined as its interior side. The green arrow (normal vector) always points from the interior to the exterior side.
- Reference volume = calculated from the visualized geometry in the visualization box, can be used to check building dimensions;
- gross volume = building volume based on outer dimensions;
- net volume = indoor air volume, based on inner dimensions

External Climate:
- As the climate files usually cover a time period of one year, WUFI Plus matches the start of the climate data by month/day/hour and disregards the year.

Opaque assemblies:
- This option allows adding one or multiple heat, moisture or air change sources (combined heat and moisture exchange with interior or exterior climate) or sinks for the selected material layer. For more information, see this article on WUFI Pro, which can also be applied for WUFI Plus: http://www.wufi-wiki.com/mediawiki/inde ... malSources . Please note: The file-input for inner sources in WUFI Plus differs from WUFI Pro. In WUFI Plus, no time column will be considered. Each row of the assigned column of the external file is used for one simulation-timestep.

Window parameters:
- If only the g-value is available, it can be entered for both “SHGC average” and “SHGC hemispherical”.

Solar protection devices:
- The overall heat gain due to incident solar radiation through a transparent component is calculated by multiplying the incident solar radiation (direct & diffuse) with the respective shading factor and the respective SHGC-value. If a constant shading factor was defined in the “Surface”-tab, it will also be multiplied.
- Thermal resistance supplement describes an additional thermal resistance that is added to the windows’ thermal resistance.
- Yes, the sunscreen device will close as long as the maximum temperature defined in the “Design Conditions” is excelled.
- You can define permanent closure of a solar protection device by using the operation mode “Schedule”. As an alternative, you could also define a constant shading factor in the “Surface”-tab.

Internal Loads/ Occupancy:
- The program uses the mean of the entered metabolisms by default.
- For clothing, you should enter the value that is most relevant for your project.
- The internal loads for lights, equipments, etc. must also be defined in this dialog.
- For the calculation of the zones’ energy balance there should be no difference between adding the systems as internal loads or as an HVAC-system. However, using HVAC-systems allows controlling them (by using Design Conditions) or adding additional options, like heat or moisture recovery for ventilation devices.

Greetings
Matthias

Dear Matthias

Thank you very much for your quick answer that was very useful.

Although, we are not sure if we totally understand all the answers.

This way, we would be very grateful if you could clarify the following questions:

Solar protection devices:

- The overall heat gain due to incident solar radiation through a transparent component is calculated by multiplying the incident solar radiation (direct & diffuse) with the respective shading factor and the respective SHGC-value. If a constant shading factor was defined in the “Surface”-tab, it will also be multiplied.
In this question we were talking about the "solar exposure for sunscreen device" that appears when you click to edit the "protection device". Is this the difference between SHGC(glass) and SHGC(glass+protection)?

- Thermal resistance supplement describes an additional thermal resistance that is added to the windows’ thermal resistance.
The same question but for U values: is this the difference between U(glass) and U(glass+protection)?

- You can define permanent closure of a solar protection device by using the operation mode “Schedule”. As an alternative, you could also define a constant shading factor in the “Surface”-tab.
We didn't find the option "Schedule" for protection devices. Could you tell us where it is?

Internal Loads/ Occupancy:
- The program uses the mean of the entered metabolisms by default.
We didn't understand this because we have to insert an unique value (per line of the day-profile) for the metabolism. Should this value be the mean value (per person) for that period?

- For clothing, you should enter the value that is most relevant for your project.
What is the meaning of "most relevant"? Why is not the mean value as for the metabolism?


Can you give us an idea about this question?
- The U value of the transparent component that we define shall already include the Rsi and Rse values? If so, why do we have the chance to change them on "general" component information?

Thank you once again for all the answers and for your attention.
Best regards,
Francisca
Sílvia