I just wanted to make sure that I understand how to map insulation correctly and I also have a few thoughts about how materials of variable thickness could work.
In EPD’s for a typical insulation product such as Flexibatts 37 from ROCKWOOL the declared unit is 1 m2 and 37 mm thick.
I will for example need to use this insulation on a 12 m2 wall in a thickness of 240 mm.
Does this mean that I can’t simply map 12 m2 of the product, since this is only 37 mm thick, when I need it to be 240 mm thick?
Should I calculate it as:
240 mm/37 mm=6.486 (I would need around 6.5 layers of 37 mm insulation to create a thickness of 240 mm)
12 m2*6,486=77,838 m2 (I would need around 78 m2 of the declared unit of insulation just to create a thick enough layer on my specific area)
When working with products of variable thickness it would be nice for the declared unit to be based on volume, this would solve the problem. But this is decided in the EPD, not by Real-Time, so is there anything to do?
Even when creating constructions of inhomogeneous layers of insulation+posts, the two materials won’t combine in the same layer, because insulation is declared as m2 and wood often in m3.
This is another reason why having the option for inulation in volume would be nice and more user friendly.
You are correct that the declared unit is decided by the EPD, therefore we cant change that.
For your two proposed calculations, both methods are correct since it yields the same end result. Personally i think the first method makes most sense, the one with 240mm/37mm=6,486. Using this thought, i would recommend to create a construction that factors the amount of insulation for the needed thickness.
So in the case of needing 240mm rockwool flexibatts i would create a construction named “Flexibatts 37, 240mm” and add the EPD to the construction and set the amount 6,486m2 flexibatts 37 pr. m2 construction.
Then when you map with this construction you will have the correct amount of flexibatts, without having to change any values of the walls square metres. This means though that you have to create a new construction for each insulation thickness.
We are working on updating the construction feature. Here you are able to create the inhomogeneous layer that need. Furthermore this means that you can have a construction with a declared unit in m3 and mapping an EPD with a declared unit in m2 to it. Thus fx. you can make the rockwool EPD practically act as an material declared in m3 as you talk about.
In the example above I have been given both length, area and volume of a material layer. This adds up a layer thickness of 70mm. If I map the Flexibatts 37 material from ROCKWOOL, the area will be chosen as the preferred material take-off and all other units will be ignore. And then the volume will behind the scenes be changed to V = Area x Thickness in EPD = 64,13 m2 x 0,037 m = 2,37 m3, without showing the change in the screenshot above.
This is really dangerous, as changing the volume will make significant errors in the calculation. This obviously stresses the importance of never using EPD’s blindly - even if they are easily available in a material library.
You suggest a feature, where you can adjust the thickness by creating a separate construction with said material. But that is still a lot of work with aaall the e.g. insulation material you might find out there. Might I suggest another solution?
Most EPD’s include a conversion factor. Would it be possible to enter an EPD in your library using the emissions data from the EPD according to the declared unit, but then add a field where you can specify the conversion factor? That way, EPD’s with a certain prespecified thickness can be converted to 1 m3, etc.
Until a liable solution is found, I suggest that a yellow pop-up message is given every time you map a construction with a material that isn’t declared in m3. That way, we as users are reminded to QA the mapped EPD.
Yes i agree that you should always make sure that you use the EPD correctly before using it.
The conversion factor idea is actually something we have briefly talked about, but it’s not something i’d suspect would be implemented in the near future, for now atleast.
Hi all, just bringing some life to this thread again..
I’m currently working on a company ‘template’ to make use of the automapping feature and I have a concern regarding this “workaround” that is suggested..
Suppose I have two exterior walls one with 240 mm insulation and one with 300 mm insulation. I can create two constructions in RTLCA based on the two different thicknesses using the same EPD data - however, when modelling in Revit I will be using the same material name in both Revit walls (ex. ‘Murbatts-34’), as it is the same material. When I go back to RTLCA and map the two walls, my material name from Revit will be the same, although I will have to map two different RTLCA constructions.. Does the Automapping feature then know how to differentiate between the two?
@Mads_Ditlevsen Maybe you could also shed some light onto this..
As I understand the Automapping feature, it will look for Revit material names in one project and map them 1:1 on the same Revit material names in the second project.
And then a development idea, @martinromby; Would it be possible to implement a ‘conversion’ factor’ as @MarkLabrosse mentions in the mapping view that requires users to enter a value before the material is correctly mapped. This conversion factor should then only be visible when the user applies an EPD where a conversion is necessary, as it currently is for all Insulation material EPDs?
Either that or make some kind of behind the scenes rule for EPDs with variable material thicknesses where the user is asked whether to use the declared unit 1:1 or have the system calculate the conversion based on EPD thickness value and the cubic meters value of the element?
I’m just doing a QA/QC of an LCA project, where insulation materials from BR18 Tabel 7 (2025) has been used. There is not one single insulation material that has been mapped correctly. They have been mapping the material from the RTLCA library, being unaware that the area of the construction was used instead of the volume they had specified.
We have now made custom constructions for each insulation type and remapped every instance.This has resulted in the project being very far from the threshold values, whereas it complied before…
This is a very serious flaw in RTLCA right now!! I suspect hundreds of LCA’s made in RTLCA are incorrect and we might be sued for green washing! This issue should undoubtedly be absolute top priority!! @martinromby@Nabil
Short-term solution
If this is not radified right now, you need to do the following:
Make a yellow error message every time someone maps an insulation material that doesn’t have m3 as declared unit. The error message should specify the problem with using the data as is.
Make a specific tutorial video for insulation materials
Long-term solution
The best option would be that you make constructions in the library for each insulation material that doesn’t have m3 as declared unit. Have the material in both the Materials-tab and the Construction-tab in the library will be really confusing, so I suggest that these are removed from the Library (or not visible for users in the Mapping tab)
The next best solution is my suggestion with the possiblity to enter the conversion factor manually.
In both cases, I still think that the error message is vital!
Thank you for raising this, and for the work you’ve put into the QA/QC. I understand why this is frustrating, and I take it seriously. You’re right that the UI and user information could and should be much clearer when adding insulation that isn’t declared in m³ to constructions.
That is the reason we are working on a full revamp of constructions. It closes this gap and makes sure users can’t set up insulation incorrectly, alongside many of the other features and improvements that have been requested.
Until that is deployed, we have already added guard-rails in the current UI when creating constructions:
The thickness field is now labelled “Thickness (m) / λ-value (W/mK)”, with a note that these materials are declared per 1 m² at R=1, so the λ-value scales the material, not the layer thickness.
If the value entered is outside the typical insulation λ range (around 0.02 to 0.06), the user gets a warning asking whether the layer thickness was entered instead.
Your suggestions are valuable input for this work, in particular the warning when mapping insulation without m³ as declared unit. A conversion factor is also a scenario we are looking at, for cases where the insulation isn’t used in a construction. I’ll make sure all of your suggestions are considered alongside the revamp.
If you can share the affected project with us (a private message works), we’re happy to take a look together.
Thanks Martin, sounds great Looking forward to seeing what you guys figure out.
The particular project I just mention is in a very early stage, so I found the error and it will be remidied without to many problems. My concern is more on a general basis. I suspect that there are many projects out there - especially since BR18 Tabel 7 (2025) was released - where LCA consultants unknowingly haven’t modelled insulation correctly. Which would be a big issue
Looking forward to seeing what you guys figure out.