# Why we need ifc parameters **URL:** \ **Category:** Uncategorized\ **Created:** [December 29, 2018, 3:47am UTC](https://forums.buildingsmart.org/t/why-we-need-ifc-parameters/802 "2018-12-29T03:47:03Z")\ **Posts on this page:** 11\ **Page:** 1
**Author:** ![Gurdev\_Singh](https://avatars.discourse-cdn.com/v4/letter/g/d26b3c/32.png) [@Gurdev\_Singh](https://forums.buildingsmart.org/u/Gurdev_Singh)\ **Post date:** [December 29, 2018, 3:47am UTC](https://forums.buildingsmart.org/t/why-we-need-ifc-parameters/802/1 "2018-12-29T03:47:03Z")
I am Bim Engineer. I am assigning the ifc parameters since one year . I have searched Google fully to know , why we need ifc parameter? I know we need ifc for open Bim means so that it can be used in other softwares . But why we need ifcexportas , ifcexporttype and ifcname these parameters. Please help me in this . I need clear picture . ---
**Author:** ![Duncan\_Lithgow](https://sea2.discourse-cdn.com/flex016/user_avatar/forums.buildingsmart.org/duncan_lithgow/32/1701_2.png) [@Duncan\_Lithgow](https://forums.buildingsmart.org/u/Duncan_Lithgow)\ **Post date:** [December 29, 2018, 11:38am UTC](https://forums.buildingsmart.org/t/why-we-need-ifc-parameters/802/2 "2018-12-29T11:38:08Z")
Please keep discussions here in the forum rather than sending SMS. I’m here because I want to read the discussions. ---
**Author:** ![Gurdev\_Singh](https://avatars.discourse-cdn.com/v4/letter/g/d26b3c/32.png) [@Gurdev\_Singh](https://forums.buildingsmart.org/u/Gurdev_Singh)\ **Post date:** [December 29, 2018, 7:23pm UTC](https://forums.buildingsmart.org/t/why-we-need-ifc-parameters/802/3 "2018-12-29T19:23:44Z")
Ok,Sir. Sorry , will keep discussion here only. ---
**Author:** ![stefkeB](https://sea2.discourse-cdn.com/flex016/user_avatar/forums.buildingsmart.org/stefkeb/32/1755_2.png) [@stefkeB](https://forums.buildingsmart.org/u/stefkeB)\ **Post date:** [January 2, 2019, 3:45pm UTC](https://forums.buildingsmart.org/t/why-we-need-ifc-parameters/802/4 "2019-01-02T15:45:49Z")
This question should be oriented towards the team that develops the Revit IFC Add-in. They chose to use custom Revit parameters (IfcExportAs…) to give the user the ability control over the way a Revit Element can be translated into a chosen IFC class (overriding the general Revit Category - IFC Class mapping that you can control in the Ifc Options dialog). ---
**Author:** ![dca](https://sea2.discourse-cdn.com/flex016/user_avatar/forums.buildingsmart.org/dca/32/195_2.png) [@dca](https://forums.buildingsmart.org/u/dca)\ **Post date:** [January 4, 2019, 7:25am UTC](https://forums.buildingsmart.org/t/why-we-need-ifc-parameters/802/5 "2019-01-04T07:25:59Z")
Hi Gurdev\_Singh! check **IFC-Manual-2018-ENU.PDF** on the autodesk website. explains how to manage the ifc parameters and class mapping exporting and importing. cheers!! ---
**Author:** ![Gurdev\_Singh](https://avatars.discourse-cdn.com/v4/letter/g/d26b3c/32.png) [@Gurdev\_Singh](https://forums.buildingsmart.org/u/Gurdev_Singh)\ **Post date:** [January 4, 2019, 10:58am UTC](https://forums.buildingsmart.org/t/why-we-need-ifc-parameters/802/6 "2019-01-04T10:58:30Z")
Sir, I tried that also I need proper reason why we need all these ifc parameters. I know why we need all cobie parameter i.e. CAFM CMMS and energy realted paramter please help me out with ifc parameters. Any video or anything . I am searching since days. ---
**Author:** ![Moult](https://sea2.discourse-cdn.com/flex016/user_avatar/forums.buildingsmart.org/moult/32/196_2.png) [@Moult](https://forums.buildingsmart.org/u/Moult)\ **Post date:** [January 5, 2019, 6:06am UTC](https://forums.buildingsmart.org/t/why-we-need-ifc-parameters/802/7 "2019-01-05T06:06:44Z")
I don’t quite understand the question, but here’s my attempt at an answer. Apologies if I have misunderstood. In short, if you do not provide any IFC parameters, then your IFC objects do not have any data. If your IFC objects don’t have any data, then your BIM model cannot be used for intelligent analysis (such as energy analysis, as per your example) in other BIM programs. This means that your model is useless outside the software that you initially created it. In addition, when your software inevitably becomes obsolete, or even moves to the next version, your BIM model is also at risk of being obsolete. Revit does not classify BIM objects the same way as the IFC standard does. For instance, underslab insulation in Revit is often modelled as a floor, or a ceiling. In IFC, it should be modelled as an IfcCovering (please correct me if I am wrong). Therefore, Revit needs a way for you to map your Revit BIM objects to IFC BIM objects. Revit provides an IFC Options dialog in its menu, but it is not a very granular way to map objects. Therefore, Revit also provides the IfcExportAs, etc parameters for custom, granular mapping. Hope that made sense. ---
**Author:** ![Gurdev\_Singh](https://avatars.discourse-cdn.com/v4/letter/g/d26b3c/32.png) [@Gurdev\_Singh](https://forums.buildingsmart.org/u/Gurdev_Singh)\ **Post date:** [January 5, 2019, 10:39am UTC](https://forums.buildingsmart.org/t/why-we-need-ifc-parameters/802/8 "2019-01-05T10:39:13Z")
Dear Moult , Thanks i got it very clear. So there are maily two ways for mapping . One is by using the IAI file(Just an example) that we select in option button and second way is by providing values to IFCExportAs and IFCExportType. Am i right ? So is there any use of IFCName parameter? And for mapping manually do we need only two parameters i.e. IFCExportAs , IFCExportType ? Please correct me if i am wrong ? ---
**Author:** ![Moult](https://sea2.discourse-cdn.com/flex016/user_avatar/forums.buildingsmart.org/moult/32/196_2.png) [@Moult](https://forums.buildingsmart.org/u/Moult)\ **Post date:** [January 5, 2019, 11:41am UTC](https://forums.buildingsmart.org/t/why-we-need-ifc-parameters/802/9 "2019-01-05T11:41:15Z")
You are correct. I highly recommend you read the `IFC-Manual-2018-ENU.PDF` recommended by @dca. As it explains, the `IfcExportAs` is an arbitrarily established convention to override a Revit object’s IFC class and IFC type. If you wanted your fancy generic model to be some form of undefined vertical separator instead, you can put `IfcSlab` as the value of your `IfcExportAs` field. If you were a bit more specific, you can put `IfcSlab.ROOF` as a value to define the class and type. Revit, for whatever reason, has additionally created an `IfcExportType` field. This is a superfluous field as the `IfcExportAs` field can serve the same function. For instance, `IfcExportAs=IfcSlab && IfcExportType=ROOF` is the same as `IfcExportAs=IfcSlab.ROOF`. In addition, Revit also supports 4 more fields to override: `IfcName`, `IfcDescription`, `IfcObjectType`, `IfcLongName` (if you want, Revit is a bit inconsistent and allows you to also call these `NameOverride`, `DescriptionOverride`, `ObjectTypeOverride`, and `LongNameOverride`). `IfcName` overrides the name parameter of the Ifc element. Every single Ifc element (i.e. all that extend `IfcRoot`) has an optional human readable name. Same with description. For `IfcObjectType`, this allows you to specify an arbitrary type of your choice for any `IfcObject`, as long as you say that the Ifc type is `USERDEFINED`. For instance, `IfcExportAs=IfcSlab.USERDEFINED && IfcObjectType=Foobar`. For `IfcLongName`, this overrides the `LongName` attribute for all `IfcSpatialElement`. For instance, an `IfcBuilding`. Personally, I don’t see the point of a `LongName` and it sounds like it is a double up of `Description`. Hopefully somebody else on this forum can advise. ---
**Author:** ![Gurdev\_Singh](https://avatars.discourse-cdn.com/v4/letter/g/d26b3c/32.png) [@Gurdev\_Singh](https://forums.buildingsmart.org/u/Gurdev_Singh)\ **Post date:** [January 5, 2019, 1:30pm UTC](https://forums.buildingsmart.org/t/why-we-need-ifc-parameters/802/10 "2019-01-05T13:30:47Z")
Thats a very nice explanation. I got all clear. The more parameters we fill the more is the information we are providing ( building smart provided parameters). Am I correct ? I am still studying the manual . ---
**Author:** ![Moult](https://sea2.discourse-cdn.com/flex016/user_avatar/forums.buildingsmart.org/moult/32/196_2.png) [@Moult](https://forums.buildingsmart.org/u/Moult)\ **Post date:** [January 5, 2019, 9:36pm UTC](https://forums.buildingsmart.org/t/why-we-need-ifc-parameters/802/11 "2019-01-05T21:36:01Z")
Yes. People usually fill them out to fit the purpose of the MVDs they are seeking to deliver, not for the sake of filling out information.