IES-VE User Forum

Hi all,

I`m quite new with IES and look forward to learn more about it. This is probably very silly detail but:

When I put a roof on the house I`m modelling and start a simulation the following error appears:

"Error: Instability in room ROOF0000. Possible remedies: reduce time step; set control radiant fraction to 0; check gain and ventilation levels; reduce macroflo opening areas".

I didn`t look at any of the suggestions because they don`t make sense and this doesn`t happen when modelling without a roof.

Thank you,

Renato.

Just reduce the timestep and see what happens. When you add a (pitched) roof it essentially creates an additional zone. Also make sure the additional zone is properly connected to the building you're modeling (with a hole element, if applicable). If you reduce the timestep to 6 minutes or less it should solve your problem.

Stable door getting closed again after the nag's done a runner...

JG's handled the issue but another thing to check is what template's assigned to the space in question - if you've got inappropriate casual gains or air exchanges (esp in a small area) you might get an instability. Also, Window size: if you have a large window try replacing with 4 smaller windows covering the same area - macroflo might not like trying to throw masses of air out at one time. While I think about it macroflo's not too happy about supplying loads of air into a space for you jus to throw it out the window right away - flowrate could lead to instability. Same goes for supplying loads of air and not letting it out.

Also... read the damned advice in the message displayed - it tells you to try reducing the time steps!