convex error-erreur convexe (solve)

H.C · Posts: 9

DB writes this error when I try to simulate my building : "Zone non convexe pour une simulation en Interieur et exterieur complet" means non convex area for full simulation inside and outside.

It works when I take off the Full interior and exterior in my simulation. But I would understand what I'm assumed to do to solve this matter.

Thanks

H.C French user

PS : Could-you take off file when matter is solve

AJ Lester · Posts: 71 Location: Auckland

Hello H.C.

Your problem is detailed in the program help under Building Models > Model Options > Drawing Tools > Solar Options.

Basically you cannot have a zone more complex than a rectangle if you wish to use full interior and exterior shading. If a zone is "non-convex" EnergyPlus cannot calculate the position etc. of sun and shade correctly.

In your model, the following zones are "non-convex":

Bloc 1 : Zone 15
Bloc 4 : Zone 19
Bloc 3 : Zone 14, Zone 12, Zone 16, Zone 2.

To correct this error, use full exterior, or, if you absolutely need full exterior and interior (i.e. if you have internal windows) then you should use zones that fit the expected requirements of EnergyPlus.

All the best,

Andrew Lester.

H.C · Posts: 9

Nice, it works better.

I hope we will have Full exterior and interior soon (DB v.2).

PS : Matter is solve could-you take off my file

AJ Lester · Posts: 71 Location: Auckland

Hi H.C.

Perhaps I didn't explain myself clearly last time.

The restriction that requires zones to be 'convex' is not a limitation put in place by DesignBuilder, rather it is a limitation in the EnergyPlus code itself.

As such, you can use "FullInteriorAndExterior" in the current release of DB, but only if all your zones are 'convex'. This is exactly the same limitation you would experience if you were to use EnergyPlus natively.

I make no claim to being an expert on the ins and outs of why EnergyPlus requires that all zones be convex, but I believe it has something to do with each wall being able to 'see' each other wall in the zone. It seems that if a window (in a wall) cannot see all the other walls in the zone, it cannot 'see' where the light it is casting will fall.

That said, unless you have internal windows, or have a serious need to know which surfaces in a zone receive which amounts of radiation, "FullExterior" should generally be adequate.

I would not expect the next issue of DesignBuilder to change the situation, simply because there is no indication that the algorithms used be EnergyPlus will (or possibly even can) be changed any time soon. Since it is EnergyPlus that is calculating all the shading factors, and it is EnergyPlus that is placing this limitation, DB is unlikely to be able to do anything about it unless the EnergyPlus code changes in this area.

Hopefully I have made it a little clearer this time around.

Bon courage!

Andrew Lester

H.C · Posts: 9

Matter is solve could-you take off my file

Thanks

Andy Tindale · Posts: 1149 Location: Stroud

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