0.00001m error with high-rise building
0.00001m error with high-rise building
I'm modelling a building with over 160m high, and there is a error with the height of the building from 134.85m on (134.85001m). I'm afraid it will influence the calculation since there might be gaps generated between storeys. Did anyone also encounter the same problem before? it's quite urgent for me, really appreciate for your help, thx so much
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huntervu28
- VE Graduate
- Posts: 68
- Joined: Mon Oct 05, 2009 1:56 am
Re: 0.00001m error with high-rise building
Don't worry about that, by default IES count 0.1m for an adjacency wall. If less than 0.1m, 2 wall will be adjacency.
Go to ModelIT / setting / model to check this value.
Go to ModelIT / setting / model to check this value.
Re: 0.00001m error with high-rise building
Hi,
These small discrepancies can creep in from time to time using ModelIt or imports from another modelling package. You could try modifying the zone geometry if you want to remove this but as long as you make sure you don' have any intersections or unmatched adjacencies then simulations should run without error (Settings >> ModelIT >> Intersections >> Check).
Note: the adjacency separation distance (again see Settings >> ModelIT) should ensure there are no external gaps caused by this.
Hope these tools allow you to be confident of the geometry you have going into the analyses on the project.
Phil
These small discrepancies can creep in from time to time using ModelIt or imports from another modelling package. You could try modifying the zone geometry if you want to remove this but as long as you make sure you don' have any intersections or unmatched adjacencies then simulations should run without error (Settings >> ModelIT >> Intersections >> Check).
Note: the adjacency separation distance (again see Settings >> ModelIT) should ensure there are no external gaps caused by this.
Hope these tools allow you to be confident of the geometry you have going into the analyses on the project.
Phil
IES Worldwide Technical Support
Re: 0.00001m error with high-rise building
Don't worry about it affecting your results. It happens all the time when you have a large model (not necessarily a skyscraper, but any building with lots and lots of zones). I'm not 100% sure on the cause of this, but my theory is that it's because the geometry (or some operation inside IES that modifies the geometry) uses a datatype of insufficient accuracy, in other words it's a programming error. Every number-crunching software is sensitive to this. For example, in Excel, in cells A1 to A33 put in the following:
=1/33
In cell A34, sum it all together using the equation
=SUM(A1:A33)
Now expand the decimals. At some point, it's no longer 1.00000000000000000 and it has to do with the datatype used. In complex calculations in Excel this can become an issue (especially when dealing with fractions).
You'll find several such errors in IES. For example, if your room height is 3.975m, when you look at the room data it is rounded to two decimal points, and some might be shown as 3.98m or 3.97m
The error just means that rooms are not the exact geometry you inputted. It also means that if you try to move them around you'll get the dreaded and hugely annoying interference errors. But your calculations will be fine. You probably do not have gaps between floors because the adjacency separation distance setting is by default 0.1m; however, if you want to make sure, select your whole building and make sure there are no exposed floors or roofs where there's not supposed to be any (sometimes in large models IES does not detect the floor below and it thinks the floor is exposed).
If you're still not convinced, you can export the GEM file, open it in Notepad, and look at the actual node coordinates in text format. If your rooms are rectangular it should be no problem finding the flaw.
=1/33
In cell A34, sum it all together using the equation
=SUM(A1:A33)
Now expand the decimals. At some point, it's no longer 1.00000000000000000 and it has to do with the datatype used. In complex calculations in Excel this can become an issue (especially when dealing with fractions).
You'll find several such errors in IES. For example, if your room height is 3.975m, when you look at the room data it is rounded to two decimal points, and some might be shown as 3.98m or 3.97m
The error just means that rooms are not the exact geometry you inputted. It also means that if you try to move them around you'll get the dreaded and hugely annoying interference errors. But your calculations will be fine. You probably do not have gaps between floors because the adjacency separation distance setting is by default 0.1m; however, if you want to make sure, select your whole building and make sure there are no exposed floors or roofs where there's not supposed to be any (sometimes in large models IES does not detect the floor below and it thinks the floor is exposed).
If you're still not convinced, you can export the GEM file, open it in Notepad, and look at the actual node coordinates in text format. If your rooms are rectangular it should be no problem finding the flaw.