WIS, Advanced Window Information System

List of Frequently Asked Questions

Dick van Dijk and Richard Versluis

TNO Building and Construction Research
P.O.box 49, NL 2600 Delft, The Netherlands

2003 - 2004
Latest update: July 20, 2004


Distribution, registration, set up and uninstall

Application area, quality, validation

Data input

Data Structure

User Interface


Distribution, registration, set up and uninstall


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Q2004-07-14-02: I have registered for WIS version 2. Do I have to re-register for WIS version 3?

A: No, you don't have to register again. The registration number for version 2 is still valid for version 3.

Q2004-03-11-01: I have registered for WIS, but the registration code is not accepted

A: Please do not add the prefix 'Mr' or 'Mrs' to the Username. Your username and organisation name should be EXACTLY the same as when you registered. Also, please register using only ASCII characters A…Z, a…z, 0…9. Do not use special characters such as á, è, ñ, etc, because these are treated differently depending on your computer settings.

Q2004-03-11-02: I have installed WIS, but which file should I doubleclick to start WIS?

A: You start WIS by navigating to the MS Windows Start button, select Programs and select the latest WIS version from the list of programs. If this option is not available, you should go to the folder where you installed WIS (default c:\program files\TNO\WIS 3.0.1 and run WIS.MDE. WIS also installs an icon on your desktop, called WIS.

Q2004-03-11-03: How can I obtain (spectral) data for components which are not in the database?

A: You need to obtain the data from measurements and import them into the WIS database. You can import data for specular panes and data for scattering devices such as shadings. You should use the correct format for the data (see the data submission guides). Another option is to contact the product manufacturer and ask them to submit the data for the WIS database.

Q2004-03-11-04: Is it possible to run WIS on a network with multiple users?

A: No, that is not possible.

Q2004-03-11-05: How can I uninstall WIS?

A: WIS can be uninstalled via standard Windows option: Start => Settings => Control Panel => Add or Remove Programs

Q2004-03-11-06: Request: possibility to supply Kobra manual (for frame calculations).

A: Kobra is developed by Physibel. Please contact Physibel to receive the manual or to purchase the latest software from Physibel (www.physibel.be)

Application area, quality, validation


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Q2004-03-11-07: Has WIS been validated or certified? We need an official paper from an official body that is approving the conformity of WIS program to EN standards.

A: At the moment there is no accreditation system for such software. Within the EU Thematic Network WINDAT the development of benchmark tests for WIS and similar programs was one of the activities, as well as systematic validation exercises. The final reports will be available in second half of 2004.

Q2004-03-11-08: Why do I find a big difference between WIS calculation according to EN 673 and EN 410 and calculation without restriction? Why does WIS allow calculation different from EN standard?

A: The difference is due to the difference in assumed environment temperatures.
Extensive answer:

According to EN 673 the U-value is determined as function of surface-to-surface-resistance at surface temperatures 2.5 and 17.5 degrees plus standard surface heat transfer coefficients (23 and 8 W/m2K).
Note: This means that the CEN standard ignores that the surface temperatures are actually a function of the thermal resistance. For single glazing the environment temperatures corresponding with surface temperatures 2.5 and 17.5 degrees and standard surface heat transfer coefficients are for instance:
radiant temperature outdoor: -1.26 [°C]
air temperature outdoor: -1.26 [°C]
radiant temperature indoor: 28.3 [°C]
air temperature indoor: 28.3 [°C]

EN 410 states that the thermal resistance of a double glazing unit under solar radiation should be taken the same as the value calculated for the situation without solar radiation; again, this is not what happens in reality: it ignores the strong effect of surfaces temperatures on the heat exchange coefficients.

Back to short answer

Data input


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Q2004-03-11-09: How do I import spectral data for 3 angles of incidence?

A: You should create three different text files and import them all using the WIS database manager, see the help file for using the database manager and see the data submission guides for the format of the data files.

Q2004-03-11-10: How do I use the WIS program for laminated glass combinations? Is it possible to combine glazings without gap in between?

A: Laminated glass combinations require importing the measured (or separately calculated) values for the laminated glazing. It is not possible in WIS to combine glazings without gap in between.

Data Structure


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Q2004-03-11-12: New structure for importing and merging databases available?

A: In version 3.0.1 (July 2004) the possibilities to import data and to merge WIS databases have been extended drastically. WIS comes with a separate program, called the WIS database manager (which can be launched from within WIS). With this program you can import data from other WIS databases, from text files and from the International Glazing Database used by LBNL's Optics and Window.

User Interface


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Q2004-03-11-13: Panes: what is the meaning of the coating code?

A: The coating code shows the kind of coating at both surfaces of the pane. The coating codes are defined in EN1096. The first character is for the coating at pane surface #1 (outdoor facing in transparent system, unless flipped). The second character is for the coating at pane surface #2 (indoor facing in transparent system, unless flipped).See also WIS help.

Q2004-03-11-14: Transparent System: what is the function of flipping a pane in a transparent system?

A: The pane should be flipped if the coated side is not faced correctly. The coating code indicates which surface is coated and the kind of coating.



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Q2004-03-11-15: Pane: is it possible to re-calculate properties of panes with modified thickness?

A: To avoid problems, it was decided within WinDat not to promote this option for the commercial glazing types .Instead, the manufacturers supply the data for the various thicknesses of panes.

Q2004-03-11-16: Shading: To what extent can WIS be used for slats with partly specular reflection?

A: For the standard calculation diffuse reflection is assumed; ray tracing model for (partly) specular reflection is implemented for advanced calculations; at the cost of increased calculation time.

Q2004-03-11-17: Shading: Is calculation of convective heat exchange and optical calculation of glazings in combination with solar shdaing devices in accordance with prEN 13363-2 or ISO 15099?

A: Yes it is, from WIS version 2.0. prEN 13363-2 has a more limited scope than ISO 15099: only normal solar incidence angle, no direct transmission of solar radiation through the blinds. WIS covers the wider scope of ISO 15099.

Q2004-03-11-18: Transparent System: can WIS be used to calculate according to EN standards, such as EN 673? There are two settings ("CEN only" and "no restrictions"); which one should I use?

A: If you choose under menu Settings: "only CEN methods allowed", the calculation will be done acording to EN 673 and EN 410. In that case the calculation will not allow that the system comprises components for which these EN standards do not apply (such as shading devices).

Q2004-07-14-01: Transparent System: I find negative g-values (total solar energy transmittance, or g-values higher than 1. That must be a bug?!

A: No, this is not a bug: the g-value includes the effect of all changes in the situation with sun and situation without sun. Consequently, the g-value in case of free (thermally driven) ventilation in one of the gaps is also influenced by the increase in the air flow with sun compared to the situation without sun. This air flow may be cold or warm. This may lead to higher than 1 or lower than zero g-values. See the Help file for more information. .

Q2004-03-11-19: If the environment radiant temperature differs from the air temperature, how does WIS determine the U-value?

A: If the environment radiant temperature differs from the air temperature, then WIS takes the weighted mean value for determining the U-value. That is correct (see also ISO 15099): it corrects for higher heat loss in case of clear sky for instance. But it does not give insight in the way 'normally' the U-value may(!) be defined: on the basis of air temperature difference.

Q2004-03-11-20: Why don't you add calculation of local temperatures for condensation?

A: WIS provides the temperature factor for the center part of the glazing (f-factor). Local temperatures for calculation of the condensation risk is more difficult: requires combined thermal effect of convection in cavity, edge of glazing and frame, which are now (is in line with EN standards) treated separately.

Q2004-03-11-21: How are the heat transfer coefficient (inside and outside surface) calculated and reported?

A: Convective: is input in Environment form; radiative: based on emissivity of surfaces; the report gives convective and radiative part separated for outdoor surface (in matrix: o_air, o_rad), but combined for indoor surface (I = indoor node).