Trying to understand wall area calculation.

[Anonymous]

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.

[Barry Kelly]

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.

[Barry Kelly]

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.

[Laszlo Nagy]

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.

[Barry Kelly]

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.

[Laszlo Nagy]

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

[Anonymous]

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.

[Barry Kelly]

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.

[Anonymous]

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.