topic Re: Trying to understand wall area calculation. in Collaboration with other software

Trying to understand wall area calculation.

Anonymous — Mon, 19 May 2014 09:35:34 GMT

Hi

I am trying to understand how i should think when i use the schedule to list out the area of walls.
I did a test where i made a 6 m thick wall and 1m hight.
The wall is a composite wall of concreat and XPS insulation.
Somehow the Schedule gives me very strange numbers that i cant really understand. Can someone explain to me how the computer is thinking when they give this information?

I am very thankful for any response.

schedule

Anonymous — Mon, 19 May 2014 09:36:19 GMT

Schedule 2

Anonymous — Mon, 19 May 2014 09:37:05 GMT

Re: Trying to understand wall area calculation.

Barry Kelly — Mon, 19 May 2014 09:57:52 GMT

I'll try to annalise your data later but are you using version 17 with 'Legacy' mode turned off? - i.e. it is using Priority Based Connections.

With PBC the surface areas off walls will not be what you expect.
The ends of wall skins will not be included in the surface areas of the walls.
No time to explain fully at this moment - I will get back to you a little later.

Barry.

Re: Trying to understand wall area calculation.

Anonymous — Mon, 19 May 2014 12:33:28 GMT

Hi Barry.

I am very grateful for your help.
Legacy Mode is turned off! should i turn it on???

Re: Trying to understand wall area calculation.

Barry Kelly — Mon, 19 May 2014 16:29:43 GMT

It is a little difficult to determine what is happening without know how you have created your composite wall.
i.e. the order of the composites, the position of the reference lines.
I can get something close to what you have but I am getting slightly different results.
Could you please select these 2 walls and then go to the FILE menu > External Content > Save Selection as Module.
Then ZIP that module file so you can attach it to this thread.
Then I can see exactly what you are working with.

The first thing is you are doing a component schedule and that will be giving you figures for each composite skin.
But in your schedule settings you have the "Show uniform items as a single entity" box ticked so some of your results are adding together.
Either un-tick this option and you will see 4 sets of figures or set up an element schedule (you won't be able to get 'Composite skin / component volume' with an element schedule though).

Look at how the wall skins trim in 3D (see attached) and you will see how one skin cuts off the same skin in the other wall.
So the length of you insulation skin is 10m on one wall but only 9m on the other - therefore gross area is 10m² on one wall and 9m² on the other.

What I don't understand is where the net surface areas or the skin volumes come from.
Or why the gross surface area of the inside is the same as the outside.
The net surface areas are clearly different.

To me these figures are wrong and I have brought this up with Graphisoft.
With PBC on (Legacy off) I think the surface areas and volumes are of no value.
Turn legacy on you will get surfaces ad volumes as they were in 16 and before but you will lose all the benefits of modelling with PBCs.

Barry.

Re: Trying to understand wall area calculation.

Barry Kelly — Mon, 19 May 2014 16:33:25 GMT

Here are the quants with "Show uniform items as a single entity" turned off.

Barry.

Re: Trying to understand wall area calculation.

Laszlo Nagy — Mon, 19 May 2014 19:04:00 GMT

Maybe this page will also help you. It explains the various schedule parameters:

http://helpcenter.graphisoft.com/guides/archicad-17-int-reference-guide/virtual-building/archicad-model-views/interactive-schedule/element-listing-parameters-in-the-interactive-schedule/wall-listing-parameters/

Re: Trying to understand wall area calculation.

Anonymous — Tue, 20 May 2014 07:52:01 GMT

Thank you for helping

MODULE TEST

Re: Trying to understand wall area calculation.

Barry Kelly — Tue, 20 May 2014 14:36:21 GMT

OK hopefully this might help to explain things and highlight what I think the problems are.

Firstly if you are doing a 'Components' schedule then don't use the 'Building Materials' and 'Components' fields together with the "Walls' fields at the same time.
You will end up with separate rows of info for your BMs and components but it will repeat the same info for the wall values on each row so you will end up with duplicate information which won't help if you are trying to get totals.

So I have used just an 'Elements' schedule for these examples.

In the attached image I have looked at just the surface areas.
The Gross areas don't allow for corner junctions, windows or door openings, Solid Element operations which is understandable.
The problem with this is the gross area on the inside is the same as the gross area on the outside - one might be usable but the other won't.

Conditional surface areas do allow for the corner junctions (and other deductions).
The problem with this is you don't get the true surface area on one side of the wall (outside in this case) because it is reduced by the with of the joining wall.

I am not sure exactly what the difference is between the 'Net' and 'Conditional' areas are. They both allow for corner junctions, windows and door openings, Solid Element operations. I think one won't allow for roof trimming.

Barry.

Re: Trying to understand wall area calculation.

Barry Kelly — Tue, 20 May 2014 14:42:57 GMT

Now a look at the lengths.

Seems pretty straight forward but why isn't the 'Conditional' length reduced the same as the conditional surface area is?

Barry.

Re: Trying to understand wall area calculation.

Barry Kelly — Tue, 20 May 2014 14:55:37 GMT

Finally the volumes.

The gross volume is the entire length of the wall x width x height so you will get a doubling up of volume at the corners because the junctions are not taken into account.

The 'Conditional' volumes do allow for the corner junctions and these will give accurate quantities as there won't be missing bits as with the conditional surface areas (the missing wall ends).

Again I am not sure about the 'Wall skin volumes' - I don't think these will include roof trimming where as I think the 'Conditional' volumes will.

This is all I have deciphered so far.
I am not happy with the inconsistency in the calculation methods for conditional surface areas and conditional lengths and that you can't get a true surface area for both sides of the walls.

Turning PBC off (i.e. turning 'Legacy Mode' on) will revert to the old method of mitring corners in 3D which will give better surface areas as the ends of walls will not be missing.
But you lose the benefits of PBC in the 3D model and sections.

Barry.

Re: Trying to understand wall area calculation.

Laszlo Nagy — Tue, 20 May 2014 20:32:36 GMT

Barry wrote:
I am not sure exactly what the difference is between the 'Net' and 'Conditional' areas are. They both allow for corner junctions, windows and door openings, Solid Element operations. I think one won't allow for roof trimming.

Barry.

The difference is that the Conditional takes into consideration preference settings when subtracting openings.
It will subtract the surface of any openings that exceed a given area as defined in Options > Project Preferences > Calculation Units & Rules Dialog, then Calculation Rules Dialog (“Reduce Wall surface by…”). The Net will subtract any opening regardless of its size, so it is unconditional in this regard.
Try to place in the wall an opening that is smaller than the size set for reduction in preferences. The Net should still subtract it, while the Conditional shouldn't because it is not a large enough opening.

Re: Trying to understand wall area calculation.

Barry Kelly — Wed, 21 May 2014 02:28:10 GMT

Thanks for the explaination Laszlo.
It is as you said.
I forgot I had my window area tollerence set very small which is why I was seeing no difference.

Interestingly a 'Crop to Roof' will deduct from the 'Gross' area but 'Solid Element Operation' will not - maybe that is by design but that seems inconsistent to me.

Barry.

Re: Trying to understand wall area calculation.

Laszlo Nagy — Wed, 21 May 2014 09:17:38 GMT

Yes, I agree, I am also baffled by the way some of these values are calculated.

Re: Trying to understand wall area calculation.

Anonymous — Thu, 22 May 2014 15:43:43 GMT

Hi

Thank you all for your help.
Your information was very useful.

I have one last question for you masters
is it possible to get the respective area of individual skins?

Example:
Outside Wall built with following skins(inside out).

Gipsum board. (finish)
Plywood (finish)
EPS (finsh)
concrete (core)
XPS (Core)
plaster. (finish)

Since the thickness is obvious in the drawings and the volume not useful, the right information would be individual areas of the skins.
When i searched for something likely in schedule I only found area on inside wall outside wall inside core outside core and center core and so on.

Re: Trying to understand wall area calculation.

Barry Kelly — Fri, 23 May 2014 02:31:47 GMT

With an 'Element' type shedule you can only get the surface area for the wall inside/outside face, the volume of the entire wall and the volume and thickness of only the inside and outside skin.
Plus the 'Air skin' and 'Insulation' skin thickness but not their volumes or surface areas.

With a 'Component' type schedule you can get the volume and thickness of each skin but not the surface area.
But you can't get the surface area for each skin.

Many people complain about 80% complete features in Archicad.
I think this is just another example of this.
I'm not sure why we can't get the surface area for each skin - it is posible with a few simple calculations on a standard wall - allowing for skin thickness and wall length/height - all of which we have now.
I am aware Solid Element Operations, roof trimming/cropping and now Priority Based Connections will all have an impact that aren't so easy to calculate but I am sure it is still possible.

This can be done now if you use the calculation lists and set up Property Objects.
This requires some GDL scripting and understanding of the calculation list sytem (which hasn't changed very much since version 6.5) and is a lot more complicated than the Interactive Schedules.

Sorry sometimes I need to have a bit of a rant.

Barry.

Re: Trying to understand wall area calculation.

Anonymous — Fri, 23 May 2014 07:28:43 GMT

Hi

Thank you Barry

Yeah the area of each skin is really useful in construction project.
This allow you to give a exact price. Next week I am starting learning VICO.
Hope VICO will help me with this problem otherwise i will have to dive into the deep sea of calculation list system in archicad.