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• Step 1- Determine what information that is available in the BIM model and what information that is relevant and can be used by IDA ICE
• Step 2 - Add or edit missing or faulty defined information in the BIM-model
• Step 3 - Export required information from the BIM model to IFC with correct properties
• Step 4 - Validate the exported IFC-file
• Step 5 - Edit and fix errors in the IFC-file using separate tools
• Step 6 - Import relevant parts of the IFC-file into IDA ICE using relevant settings depending on the content if the IFC file
• Step 7- Map IFC-objects to corresponding IDA ICE objects
• Step 8 - Shift the IFC model to the right position
• Step 9 - Convert imported IFC objects into IDA ICE objects
• What level of geometrical complexity should IfcSpaces have and how can it be adjusted?

What is the recommended process to import BIM into IDA ICE?

There are many ways to import BIM into IDA ICE depending on the situation, the role of the user and available data but this is a recommended method.

1. Determine what information that is available in the BIM model and what information that is relevant and can be used by IDA ICE.
2. If needed, add or edit missing or faulty defined information in the BIM-model.
3. Export required information from the BIM model to IFC with correct properties.
4. Validate the exported IFC-file.
5. If needed, edit and fix errors in the IFC-file using separate tools.
6. Import relevant parts of the IFC-file into IDA ICE using relevant settings depending on the content if the IFC file.
7. Map IFC-objects to corresponding IDA ICE objects.
8. If needed, shift the IFC model to the right position.
9. Convert imported IFC objects into IDA ICE objects. This can be done automatically, manually or in a combination.

Often IDA ICE users have little possibility of affecting step 1-3 and need to rely on IFC-files created for other purposes, for example coordination or collision control. If this is the case, step 4-9 is more important and requires more interaction by the IDA ICE user.

Step 1- Determine what information that is available in the BIM model and what information that is relevant and can be used by IDA ICE

This step assumes that the IDA ICE user has access to the original BIM file, most importantly, the architectural model, and preferably some basic knowledge about the architectural BIM tool like Revit or ArchiCAD. Optionally that the IDA ICE user and owner of the BIM file perform this step together.

The most important objects in the BIM file are objects that can be directly converted into equivalent IDA ICE objects, i.e. rooms/spaces, windows/transparent curtain wall panels, walls/curtain walls, doors, slabs and roofs together with materials and constructions. Other objects that can indirectly be converted are shading objects, PV-panels, HVAC objects like terminals, air handling units and radiators. Finally, some objects can be relevant depending on the type of study that will be performed in IDA ICE, for examples furniture could be relevant for daylight and CFD studies.

Also make sure if there are other relevant sources for BIM import, for example construction or HVAV models. Apart from BIM, other sources for information can be very useful to understand the project and help create a simulation model, for example illustrations, general descriptions, drawings and contractual documents.

The quality of the BIM models varies throughout a project and therefore it is important to know the expected quality of the data available but also what information that might be missing. Some common problems are

• Windows including frames are placeholder objects
• Wall constructions including wall thickness are generic
• Room names are not set
• Floor layout might change
• Beams and columns are missing

The good thing about architectural BIM tools is that they can give a good overall picture of the project, for example floor plans, sections and 3D views. These can be very useful when determining what data is available and how this can be translated into a simulation model.

Step 2 - Add or edit missing or faulty defined information in the BIM-model

This step is highly dependent on what BIM tool is used and the purpose of the IDA ICE model. Also, this step is only relevant if the owner of the BIM model is willing to create a custom IFC model intended for IDA ICE import or if the IDA ICE user has access to the (architectural) BIM model or a copy of this.

The most important object of an architectural model are floor slabs since they define the areas and levels of the building. Usually, BIM files contain slabs.

The second most important object is the windows and other transparent objects since they have a very large impact on the thermal simulation model and are very time consuming to create manually. Usually, BIM files contain windows and transparent curtain wall panels.

Walls are also very important, first of all, they can be used to create building bodies and thermal zones but they also are containers of windows and doors.

Finally, rooms, spaces, zones and areas can be used to create IfcSpaces that can be used to crate building bodies and thermal zones. Until IDA ICE 5.1, IfcSpaces were necessary.

Some common problems are

• Rooms/spaces/zones are not created
• Rooms/spaces/zones are not representing the intended thermal spaces
• No areas represent building bodies
• Columns and beams are room bounding
• Walls and not correctly defined as internal/external.
• Walls should preferably not overlap

Create IfcSpaces in Revit

IfcSpaces can normally be created from three types of Revit objects, rooms, spaces and areas. Rooms and spaces are almost identical 3-dimensional objects with the exception that rooms usually are defined and created by architects and spaces are created by MEP engineers based upon rooms. By default, spaces contain more data, typically regarding HVAC systems. Rooms and spaces can be generated from walls and other room bounding objects but also created manually by using room separator lines. Generated rooms can also be edited by room separator lines, for example simplifying or dividing rooms. Spaces generated from rooms can be divided further by separator lines, but they cannot be larger, i.e. rooms cannot be merged into larger Spaces or IfcSpaces. It is not possible to have different sets of rooms or spaces in a model, for example letting them represent different object types without creative use of phases. Areas are much more flexible compared to rooms and areas and can overlap and be larger than rooms and spaces. The major difference between rooms/spaces and areas is that areas are 2-dimensional. One common application for areas is to define building bodies.

One interesting concept in Revit is that rooms and spaces are surprisingly difficult to delete. It is not enough to delete them from floor plan, but they need to be deleted from a schedule.

To see rooms in Revit, they need to be visualized. By default, they are not shown in floor plan or section. Rooms and spaces cannot be visualized in 3D in Revit

Rooms and spaces should usually fill the whole air volume from floor to roof. In this image the room starts 550 mm above the floor.

To adjust this the base offset needs to be adjusted 550 mm as shown above.

It is very important that the Area and volume computations settings shown above is set to “Areas and volumes”, otherwise all rooms will be prismatic boxes and not have correct shape as shown above where rooms extend through the roof.

The same model with Area and volume computations settings shown above is set to “Areas and volumes” instead of ”Areas only”

To follow the convention that zones and building bodies should be defined at the inside of walls, floors and roofs it is important that room area computation is set to “At Wall finish” shown above.

To make rooms extend all the way to the roof it is important that the “Limit offset” is set to a value higher than the ceiling.

Slabs, roofs and walls needs to be set as room bounding to create correct rooms and spaces. If not, rooms could overlap and or have faulty volume as shown above. Usually false ceilings should not be room bounding.

Columns and beams should not be set to room bounding as shown above. Otherwise, exported IfcSpaces will have holes in them. This is hard to see in Revit since zones cannot be visualized in 3D.

One of the most important aspects when creating rooms or spaces in Revit to be used in IDA ICE is that they should have the same volume and name as the intended thermal zone in IDA ICE. This means often that they should be quite simple with no internal room bounding objects like columns or beams.

Room separator lines shown above can be used to simplify the shape of a room or divide it. This is useful if the façade consists of numerous columns and or curtain wall elements.

Rooms can be merged in Revit by dividing internal walls not room bounding or even delete them but it is probably better to merge the spaces in IDA ICE to keep consistent room definitions in IDA ICE and the architectural BIM model.

Even if some objects cannot be automatically imported into a relevant IDA ICE object, for example wind turbines or a large chimney, these objects could still be relevant for the model and should be distributed. Also, objects like furniture could be relevant for daylight or CFD analysis.

Visualize rooms in Revit

Unfortunately, it is not easy to visualize rooms or spaces in 3D in Revit and this makes it hard to validate the model quality before exporting to IFC. It is possible to visualize rooms in floor plan and sections and in 3D using plugins or custom scripts.

Create IfcSpaces in ArchiCAD

There are a number of ways to create IfcSpaces from ArchiCAD but the most common way is to create and export ArchiCAD zones. Zones are used to create rooms and areas and can be assessed from the zone tool together with a number of constructions methods, for example “Inner edge” for automatic creation and “Reference lines” for a more manual creation.

Visualize rooms in ArchiCAD

Zones are by default not visible in 3D view in ArchiCAD but can be visualized using “Filter and Cut Elements in 3D”, selecting Zone.

Step 3 - Export required information from the BIM model to IFC with correct properties

This step is highly dependent on what BIM tool is used and the purpose of the IDA ICE model. Also, this step is only relevant if the owner of the BIM model is willing to create a custom IFC model intended for IDA ICE import or if the IDA ICE user has access to the (architectural) BIM model or a copy of this.

In principle it does not matter how the original BIM file was created and what information it does contain if this is not sent in a structured way to IFC. Still, a well-structured BIM file makes it much easier to export to IFC using mainly default settings. Some general tips exporting IFC to IDA ICE are:

• Do not export unneeded information. This will make the IFC large and slow to import in IDA ICE.
• Avoid exporting objects as proxy elements since these objects would be hard to use in IDA ICE.
• Export transparent doors and curtain wall panels as IfcWindows.
• Preferable, export gross floor areas as IfcSpaces.
• Make sure that rooms/zones/spaces are exported as IfcSpaces.
• The entire building should be exported into a single IFC-file. It is not recommended to split the export into separate stories.
• Different buildings should be exported into separate IFC-files to minimize the size of the IFC-file and number of storys.

Export IFC from Revit

In IFC - as in Revit - there are types and instances for most entities. In the past, the Revit IFC Exporter forgave an incorrect assignment in the configuration files, but due to various adjustments and general improvements to the IFC Exporter, this is no longer possible in newer versions. For the export of type parameters, it is no longer sufficient to specify the IFC class, e.g. IfcElement or IfcWall, but it is mandatory to specify the type (e.g. IfcElementType or IfcWallType).

Since IDA ICE does not have an equivalent of transparent curtain wall elements they should preferably be exported as IfcWindows shown in the illustration below.

It is recommended to export IFC from a 3D view where all objects are visible. Please note that rooms and spaces are never visualized in 3D.

If no 3D view is available in the model a new one can be created from View tab shown below.

To export IFC from Revit, use File->Export->IFC as shown below.

Setup

A recommended setup-file can be downloaded here.

IFC should preferably be exported as 2x3 version

Category mapping should be limited to objects intended for IDA ICE and transparent curtain wall panels and doors should be exported as IfcWindows.

A recommended template can be downloaded here.

IFC and Walls should be split by level. IDA ICE does not use space boundaries, but ESBO does and therefore it can be good to export these as well, preferably as 2^nd level since this usually produces better results than 1^st level space boundaries.

It is very important to export rooms, spaces and areas

Even if Revit property sets are not used by IDA ICE it can be useful to have them in the IFC model.

Does it matter if the walls in Revit are external or internal?

Yes. This information is important for IDA ICE to be able to create building bodies from IFC and defining IFC walls correctly. Unfortunately, this is far from trivial in Revit. More information can be found at https://user.buildingsmart.org/knowledge-base/how-to-deal-with-isexternal-property-using-revit-2020/

Exporting IFC from Revit without license

It is recommended to have a Revit license to export IFC files, but it is not necessary as long as you have access to the Revit file. Revit files can be opened and export IFC-files in Revit in demo mode if no changes are made to the Revit model.

Note that Revit files should always be opened Detached from Central.

There are also other BIM formats like dot bim and Speckle that allow export from Revit in demo mode even if the model is changed but these formats cannot be imported directly into IDA ICE but require external tools like Blender/Bonsai.

Export IFC from ArchiCAD

Before exporting zones and other objects to IFC from ArchiCAD it is important to visualize them, preferably in 3D. This can be done by creating a general 3D view, open “Filter and Cut Elements in 3D” and make sure that elements that should be exported are shown, most importantly Zones since they are by default not shown in 3D.

Select all objects that should be exported, for example use CRL+A and use File > Save as... or File > Interoperability > IFC > Merge to IFC Model.

Make sure to export relevant objects, most importantly walls, roofs, slabs, windows, doors and zones.

Exporting IFC from ArchiCAD without license

It is recommended to have a ArchiCAD license to export IFC files but it is not necessary as long as you have access to the ArchiCAD-file. ArchiCAD files can be opened in demo mode model. Even if IFC export is not allowed in demo mode it is possible to merge IFC to an empty IFC model and generate similar results. An empty IFC-file can be found at the EQUA Wiki,

IFC space boundaries

IDA ICE does not need space boundaries since adjacency between is determined automatically using geometrical relationships and building bodies. Also, space boundaries generated from most BIM tools are not reliable. Therefore, space boundaries are not imported or used by IDA ICE. In contrarily of IDA ICE, ESBO uses IFC space boundaries, and it is therefore recommended to export these during IFC export from BIM tools.

Step 4 - Validate the exported IFC-file

It is highly recommended that the exported IFC is validated to include requested information using a dedicated IFC viewer. There are some IFC viewers dedicated to this, for example Simplebim with the IDA ICE Addon. Other useful IFC viewers are DDS-CAD viewer and KITModelViewer (FZKViewer). Knowing the content and quality of the IFC can help the IFC import into IDA ICE, most importantly if IFC geometries should be imported, if there exists IfcSpaces and if Ifc elements are properly defined.

Simple BIM

Simplebim Desktop is a BIM software that can for example, validate and edit IFC models to be used by IDA ICE. More information can be found at https://support.simplebim.com/category/use-cases/use-case-ida-ice/

Step 5 - Edit and fix errors in the IFC-file using separate tools

This step can be very useful, especially in projects where the IDA ICE user has little impact on the content and quality of the IFC file and that the IFC is not intended for building simulations in IDA ICE. The most common tools to use are the following.

Simple BIM

Simplebim Desktop is a BIM software that can for example, validate and edit IFC models to be used by IDA ICE. More information can be found at https://support.simplebim.com/category/use-cases/use-case-ida-ice/

abstractBIM

abstractBIM is a cloud based free service to clean up and edit IFC files to be used by IDA ICE. abstractBIM requires IfcSpaces in the IFC file. More information can be found at https://www.abstractbim.com/

Blender/Bonsai

Bonsai for Blender is an open source free tool to edit and create IFC files.

Step 6 - Import relevant parts of the IFC-file into IDA ICE using relevant settings depending on the content if the IFC file

During import there are several available settings that can be used depending on the content and quality of the IFC model and the intended use of the IDA ICE model. The most important ones are the following.

Merge windows

The number of windows has a big impact on simulation speed and many objects in a model can affect refresh rates negatively. Due to this, IFC import in IDA ICE have the option to merge IfcWindows during import. As default on, all the windows are merged into a single window for each wall with the area equal to the total area of all the windows. If off, each window is imported as a separate window.

By merging windows, several things need to be considered:

• The shading and surface temperature will be the same for all merged windows.
• Thermal bridges will not be the same as for individual windows.
• The position of the merged window will not be identical as for the individual ones.
• The result for daylight, CFD and detailed comfort simulation will differ quite a lot between merged and not merged windows. For energy simulations, not as much, depending on the description of thermal bridges.

Use grosspaces

During IFC import IDA ICE tries to create building bodies. Unfortunately, there are no such IFC objects that represent building bodies and usually BIM models do not have this concept either. Still, sometimes there are similar concepts that can be translated into building bodies. One of these is the Revit Gross Area Plan. These are 2-dimensional areas that represent total constructed areas of a building. These areas can easily be created in Revit and are by default exported as 3-dimensional IfcSpaces, usually covering the whole floor plan and thus provides a good geometry for a building body representing that floor, as long as the level of geometrical complexity is low, i.e. prismatic with flat roof.

IfcSpaces representing building bodies will be indistinguishable from those representing rooms and spaces.

If there is an IfcSpace in the IFC model, i.e. a space created from grosspace, that covers every other IfcSpace on the storey and “Use grosspaces” is selected during IFC import the shape of a building storey is taken from this IfcSpace an IDA ICE IFC space is created depending on the “Keep intercepting spaces” setting. Preferably, the grosspace should be defined using inside of external walls since this is how building bodies in IDA ICE are defined.

In Simplebim it is possible to set a special property, “Is Building Body”, that can be set to “Yes” to help IDA ICE determining what IfcSpaces that should be used as building bodies.

Ignore roofs

If “ignore roofs” is set to off, the default value, IDA ICE tries to create editable building bodies with complex roof shape. If set to true, IDA ICE ignores the shape at set to a plane roof at the top of the roof. In any case an IFC geometry with the shape of the roof will be created if possible. If the roof shape is too complicated, the import from IFC can fail just because of the complexity.

Unfortunately, IDA ICE seldom succeeds in creating meaningful building bodies from complex roof shapes and therefore there are several commands available to create building bodies from IFC geometries, for example extruding downwards and truncate (see separate chapter on how to create building bodies from imported IFC geometries).

IFC geometries options

During IFC import IDA ICE created two kinds of objects, IFC objects and IFC geometries. Often each IFC object has a corresponding IFC geometry related with its name inherited from the IFC file. There are some relevant things to remember

• All IFC objects can be seen in the IFC details table found in the lower part of General tab after import in IDA ICE.
• IFC geometries are usually polyhedrons and can be duplicated into valid building bodies, zones and other relevant IDA ICE objects.
• IFC geometries are not visualized in floor plan.
• IFC objects are not visualized in 3D if there are IFC geometries in the model.
• IFC slabs use corresponding IFC geometries to store the shape.
• IFC windows and doors do not include corresponding IFC geometries, but these can be imported anyways.
• It is possible to delete IFC objects and IFC geometries independently of each other, but it can cause unexpected behavior of IDA ICE and should be done with caution.
• IFC objects and geometries can be created using duplicate commands.
• IFC objects can contain some basic BIM data, IFC geometries contain no data except its name and geometry.

IfcSlabs, IfcWalls and IfcRoofs are always imported as IFC geometries even if they sometimes are simplified. The reason for this is that IDA ICE IFC walls are simple rectangles described by two points. Therefore, corresponding IFC geometries are used for 3D visualization and for slabs, also for determining the exact shape.

Other Ifc objects can optionally be imported if they are polyhedrons. By default, IFC geometries contain more than 1000 faces and 2000 polygons are not imported since this could cause memory problems. These values can be changed in IFC geometries options.

The reasons for importing IFC geometries are:

• Duplicating into IDA ICE objects like building bodies, zones, skylights and balconies.
• Validating the import process by having a visual representation.
• Duplicating into CAD objects and CAD geometries for daylight and CFD simulations
• Making visualization more appealing.

Keep intercepting spaces

The IFC import assumes that IfcSpaces in the IFC files should represent thermal spaces. In real projects, this might be true, but IfcSpaces can be generated from a number of BIM objects, intentional or not. Therefore, there might be IfcSpaces that should not be imported as thermal spaces and IfcSpaces intended to represent building bodies. Due to this, the generation of thermal spaces from IDA ICE IFC spaces is not fully automized and the user also has the possibility to limit the generation of IDA ICE IFC spaces that are overlapping since IDA ICE does not allow overlapping thermal spaces. The main reason for intended overlapping IfcSpaces are that the larger ones represent building bodies, see “Use grosspaces”. If “Keep intercepting spaces” is set to Off (default), any two spaces covering same space (even partly) the bigger one will be removed, otherwise all spaces are imported. If option “Use Grosspaces” is on and option “Keep Intersecting Spaces” is off, the shape is taken and the grosspace is removed afterwards.

To choose on for Keep Intersecting Spaces is recommended only for an experienced user. The reason for keeping intersecting spaces is to replace automatic choice with manual one. For example, if an unnecessary space is the smaller one of two intersecting spaces. By clicking on a point belonging to a few spaces the user gets a menu which of spaces he/she wants to select and either remove or transform to a zone.

Take space text attributes from slots

There are many important reasons to structure data in IDA ICE, especially thermal zones. In IDA ICE thermal spaces have individual names but also a group parameter that is used during IFC import. Since IDA ICE 5.1 there are also custom name and number parameters that can be used for any purpose and some localizations have more space parameters like floorplan.

In BIM models rooms, spaces, zones and areas can have several parameters describing structured data like groups. Also, when exported to IfcSpaces these can be exported into IFC models such as ifcName, ifcLongname and ifcDescription. During import, the user should identify what is what and by choices place the names right in IDA.

Quite often ifcName is just a number. So, if you have three rooms with ifcLongname Hall and ifcNames 1, 2, 3, it is better to see their names as Hall-1, Hall-2 and Hall-3. For that you choose Auto. If the data is rearranged non-standard way, the default choice will give you unsatisfactory result. To solve this, reimport the IFC and select the suitable options based upon the previous attempt. You can see an example what could be found in ifcName, ifcLongname and ifcDescription.

Unfortunately, there are much more places where CAD programs can put individual and group names of spaces. For some big projects were written add-on functions to find and extract these names. The choice Other refers to such special function (if any). Standard IDA has no such function attached. So, the choice Other in the standard edition is the same as Auto.

Step 7- Map IFC-objects to corresponding IDA ICE objects

It is highly recommended to map IFC data during import even if the quality of the data is questionable since this can give an indication of window, door and wall types.

It is not possible to map constructions without “Import from IFC”. Note that by default all material properties will be set to 1.

When a zone is created in IDA ICE, it is necessary to provide some additional information, including wall and window constructions and material properties. One can consider an imported style name of a wall, a window or a material as a clue to such information. The user can map each style name imported from IFC to an appropriate construction or property in an IDA ICE database. If a style name is not mapped, then a default construction or property set will be used. (Note that also the default can be mapped).

Step 8 - Shift the IFC model to the right position

During IFC import, IDA ICE places elements locally in the IfcSite coordinate system instead of the IFC global coordinate system. Due to these settings IFC objects and geometries can end up far from origo and quite often is the intended ground level high up in the air. Due to this, there is an IFC shift command that can be used to move all IFC objects and building bodies with a given offset. Offset can also be calculated using base- and target points. By default, a recommended offset is created after IFC import. This is removed after importing so to use this offset, the shift command should be used directly after IFC import into IDA ICE.

Step 9 - Convert imported IFC objects into IDA ICE objects

Prismatic thermal zones

Spaces can be merged by the user, either during the conversion from IFC space to thermal space using the option “Make a single zone from all marked IFC spaces”

or selecting two or more thermal zones and select “Merge zones”. This will also create internal wall masses representing missing internal walls. Spaces must lie at the same level and have the same height to be merged into a single simulation zone. When a zone is created from a single space, its border coincides with the border of the space. When a zone is created from several adjacent spaces, its outer border is a polygon that envelops all the spaces.

Prismatic thermal zones with complex roof shape or thermal zones with complex geometry

There are two methods to create zones with complex roof shape from IFC

1. Crete a building body with complex roof shape and let the zone have room height “to roof”. This will automatically create a ceiling with the same shape as the building body as long as the shape is not too complex.
2. Import the space as an IFC or CAD geometry and duplicate this into a thermal space.

To create an IFC geometry from IFC space, choose “Geometries for IFC spaces” in “IFC geometries options”.

Imported IFC space geometries can be listed and visualized in IFC details table.

Note that IFC spaces are prismatic and does not contain any holes.

IFC space geometries can be duplicated into building bodies or directly into thermal spaces.

Curtain wall panels

If transparent curtain wall panels are not exported as IfcWindows they are probably exported as IfcCurtainWall and the glazed parts as IfcPlate. These will not be converted into IFC windows but they will be imported as IFC geometries in IDA ICE representing a simplified wall. The Curtain wall can be visualized as shown below.

IfcPlates can be filtered using the Type column in the details table.

By selecting the IfcPanels in details table or 3D view, right click and select “Duplicate as face window(s)” the geometries are if possible duplicated into windows. This assumes that there are suitable building bodies to host the windows.

Before face windows are created, users have the option to map them to ICE windows.

Please note that it is only the panel that is duplicated into a window using this method and therefore the window frame is not included. If the default windows frame area fraction is used the glazed part will be underestimated. Therefore, it is recommended to adjust the size of curtain walls modelled as windows. Solid parts of curtain wall elements are usually imported as IFCMEMBER type and can be converted into shading CAD objects or even wall parts with different U-values. To convert IFC geometries to wall parts they need to be converted into three steps, first duplicated into face windows or openings moved to zones and finally replaced into wall parts.

Skylights and windows in sloping walls

IDA ICE IFC windows can only belong to IFC walls and IFC walls are always vertical. Therefore, IFC windows in IDA ICE can only be vertical. For this reason, skylight and windows in sloping walls are not imported as IFC windows. Still, windows can be created from any geometry that resembles a window. During IFC import it is possible to import additional IFC geometries from IFC objects in the IFC file as IFC geometries if they are polyhedrons.

IFC geometry import settings

These geometries can be identified based upon their object type in IFC geometries details table or in the 3D tab and be duplicated into Façade windows.

For this method of working there needs to be a building body with a façade or roof near the geometry representing the window with the same direction. Also, the geometry needs to resemble a window. If the command does not work, it might help to simplify the geometry further by using the “Duplicate into box” command (Currently in Beta).

The downside with this method is that no other information than size and location is imported, for example Window type and that IDA ICE does not store the ID if imported CAD objects that means that multiple windows can be created from the same IfcWIndow without warning.

Nonrectangular windows

Even if IDA ICE 5 supports nonrectangular windows IDA ICE IFC windows are defined with only 2 points and therefore only rectangular windows are created. IFC windows can optionally be imported as geometries and duplicated into IDA ICE windows but are still only duplicated into rectangular windows. One option is to manually edit windows and convert them into resource objects and replace relevant windows based upon type.

Glazed doors

IDA ICE does not support glazed openings and doors. The BIM import in IDA ICE will automatically convert IfcDoors into (IDA ICE) IFC doors and as Openings with or without door during zone creation. One way to model glazed doors is to model them as windows with large frame fraction Openings can easily be replaces with windows by selecting them in details table or 3D, right click and use “Replace…”

Window frame fraction

IFC files seldom contain this information, and it is not possible to extract this information from the geometry in the IFC either due to the many ways geometry can be described. If the IfcWindows can be imported as IFC geometries, assuming that they are polyhedrons, they can be visualized, preferably using X-ray visual setting in the 3D tab to manually determine frame fraction. For more complex shadings it is possible to import frames as shading imported cad geometries but please note that transparent objects like glass panes will also shade. Therefore, these models must be generated and edited without transparent objects before import into IDA ICE. Useful tools are Sketchup, Blender and Rhino.

HVAC objects

HVAC objects like ducts, radiators and terminals cannot be imported as IFC objects or IFC geometries. If they need to be imported as IFC geometries, they need to be exported from the BIM tool as IFC element types that can be imported in IDA ICE like IFC building element proxies.

Balconies

Balconies can be imported as IFC geometries. IFC geometries can be duplicated into shading CAD objects. It is also possible to duplicate IFC geometries into IDA ICE balconies indirectly by the following steps:

1. Duplicate IFC geometries representing balconies (for example slabs) into CAD objects.
2. Duplicate the CAD geometries from step 1 into Face windows. This assumes that there are building bodies to host the windows.
3. Replace the windows created in step 2 with balconies.
4. If needed, remove CAD objects created in step 2. Still, due to limitations in IDA ICE balconies, it can be useful to represent balconies with both CAD objects and balconies to simulate the effect of shading and thermal bridges.

Please note that CAD- and IFC geometries created from balcony railings can be very complex and have a negative impact on simulations speed. Therefore, it can be useful to simplify these geometries before simulation, for example approximate them with simple boxes or shading objects with fixed transparence. The downside of this is that shading will not be angle dependent.

Optical properties

IDA ICE does not import surface properties from BIM. The reason for this is that IFC-files seldom contains surface properties in a consistent way. Since the BIM import in IDA ICE can automatically map IFC constructions to ICE resources using “Import from IFC” these constructions can be used to identify different surface materials.

Should IFC shade by using “Calculate the shadow”?

Probably no. IFC models usually contain many IFC geometries and if the IFC model is selected to shade this includes all IFC geometries including windowpanes and other objects that are probably transparent. Also, the entire IFC model will have the same optical properties. Therefor it is recommended to duplicate selected IFC geometries into one or many CAD objects/CAD geometries where each CAD object can have unique optical properties.

Merging spaces/zones and building bodies

BIM model should preferably be imported 1:1, i.e. each BIM object like a zone, wall or window should be represented by an equivalent IDA ICE object. In reality this is not possible since many BIM objects do not have equivalent IDA ICE objects, for example curtain walls, but also since IDA ICE models should contain as few objects as possible to simulate fast and efficiently.

• If zones are merged it is harder to update them automatically if the IFC model changes. Individual zone ID:s are stored as hidden parameters in zones consisting out of one or many IfcSpaces. This is especially important if the result is exported from IDA ICE to IFC.

It is not obvious how buildings should be divided into building bodies but here are some general recommendations:

• Try to keep building bodies editable, i.e. prismatic with an editable roof. IDA ICE will try to keep building bodies editable after merging but will not always succeed.
• Building bodies should preferably not have gaps between them and not overlap.
• Too many building bodies have a negative impact on performance and simulation time.
• Merging building bodies can cause unexpected geometries.
• It can be a good idea to have one building body per floor, especially if they have different outlines.

Merging zones and building bodies are a very complex operation and should be done with caution. Here are some general recommendations:

• Save the model before merging. The commands are in beta and can cause unwanted geometries or even geometries missing that can be hard to undo.
• Avoid having objects like windows and measuring planes placed on zones and building bodies that should be merged since these objects can be damaged by the operation.
• Often there might be very small distances between building bodies created from BIM that can be hard to see but can cause problems with merge. Sometimes it might help to fill these gaps with a temporarily building body.
• Building bodies and zones should preferably have a single surface connecting them before merging.
• Changing the distance between two zones or building bodies can help merging. This includes making the objects overlap. For example, in the illustration below two zones should be merged, but it is not obvious how this should be done. There are several options:
  • The zone to the right should extend to the left.
  • Both zones should extend to each other.
  • The zone to the left should extend to the right.
  • A more complex shape should be created.
  • The two zones should keep their size but be treated as single zone with two closed volumes.

IfcOpenings imported as geometries

Sometimes import of IfcWindow and IfcDoors fails, or they might even be missing from the IFC model. Still, there are often a special IFC object called IfcOpening in the hole of the wall or slab with the same size and position as the window or door that can be duplicated into a Face window or door or even an IDA ICE IFC window or door.

Please note that different BIM tools create IfcOpenings differently and often they are much deeper than the object that they belong to and often several IfcWindows can be contained in a single IfcOpening.

Also, IFC geometries representing IfcOpenings will cover other objects in 3D view and it is therefore useful to use the X ray view setting when these are present.

What level of geometrical complexity should IfcSpaces have and how can it be adjusted?

The level if detail of exported IfcSpaces should correspond with the purpose of IDA ICE simulations. For example, an energy simulation usually requires less detail than thermal comfort, daylighting and CFD. This includes internal partitions, columns and beams.

In Revit there are a few ways to change the level of geometrical complexity

There are two methods to import IfcSpaces into IDA ICE, as IFC spaces or optionally as IFC or CAD geometries. IDA ICE IFC spaces are simplified during import since they are imported as prisms with constant vertical height and vertices that are connected with a side shorter than 0.5m are merged to avoid short walls. Also, internal enclosures and holes are excluded. Spaces imported as IFC geometries are not simplified and imported as polyhedrons. This means that they can be non-editable.

IFC-files without IfcSpaces

Even if there are no IfcSpaces in the IFC model it still contains a lot of useful information and IfcWalls can be used to create thermal spaces. The downside with IFC models without IfcSpaces is that zone naming will be inconsistent and that it is not possible to send room result like cooling and heating power to MEP BIM tools like MagiCAD.

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