How Much difference occurs when you dont model the following

[Marc Jensen]

Hi All.

We are having a debate as to how much of a difference modelling ceiling spaces into the building and wall thicknesses.

We currently take the architects drawings and model the walls as the center of theirs.

Some rooms have a ceiling cavity of 800mm dropping to 400mm below beams, In the past we have modeled without ceilings unless we have been setting our ventilation as ach. (Affected by volume) but usually we model it as having no ceiling and inner wall spaces.

If we tick model inner wall volumes, does that also model the ceiling space as specified in the constructions?


We try to keep our models as simple and concise as possible. Is it prudent to start modelling the inner volumes etc.


One of our reasons why we dont model the inner volumes as when we change the insulation types to get the required R Values we set the insulation and then tweak the thicknesses to get the right total R value (1 / U Value) We dont use IES's total R Value as we dont know how it gets that data etc....


I would be interested to hear from other professionals regarding this and their standard modelling procedure.

[bootsam]

When modelling a building I create my own DXF from the artichokes GA's. I do this by tracing round each room making sure i have an end point where i want to snap to in IES. I generally use polyline in Autocad for this. I too go down the middle of partitions and ignore false ceiling and floor voids. I draw each room separately. I do not draw the overall floor plan and then divide it up as from experience ive noted that IES will wait until your 99% finished doing this before it gives you unmatched adjacencies errors. Thus its just easier for me to draw them separately in the first place. In practice this means my room volumes may be slightly greater. However it is my view that it is better to have marginally greater loads than marginally less loads. Besides we all apply margins afterwards and with heating systems dont forget we also add start up capacities of up to 20%.

It is my experience that artichokes cannot draw in 2D, let alone 3D. They can never seem to snap to perpendicular or end point and they always seem to leave gaps. I guess the results of frequent changes and rushing to get things done at the last minute. Something we can all relate to.

Once i have traced every room, i cut and paste my outlines into a new dxf file. This way I also get rid of their silly layering. Once I have done all floors i will then paste each floor as a block on top of my ground floor one just to make sure it lines up smooth on the periphery as sometimes we need the rendered model for a report and it helps if it looks nice and even.

So in summary. Make your own dxf. Dont use their GA's.

[Marc Jensen]

Thank you for the reply:)

That is essentially what I have been doing.

Whilst initially it seems more time consuming to redraw the lines and remove the excess layers, I find in odd floor shapes this is a godsend. Especially if you have a wall with ten or so lines displaying anything from wiring to constructions. I would say that using a keyboard with macro functionality really helps in ARCHICAD so you dont need to keep typing in or pressing enter etc you can just press one button and it will start up a new line or extend or trim easy.

In the past I have always snapped to dxf. However my next model I will trial snapping to a fine grid so that i can get a model with no slivers etc