[Bldg-sim] Input wanted: IES VE vs DesignBuilder

Nick Caton ncaton at smithboucher.com
Thu Jul 31 06:05:28 PDT 2014

Chris – thanks for sharing your thoughts and experiences!

It is helpful for many of us tuning in!

[cid:489575314 at 22072009-0ABB]


Smith & Boucher Engineers
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olathe, ks 66061
direct 913.344.0036
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From: Bldg-sim [mailto:bldg-sim-bounces at lists.onebuilding.org] On Behalf Of Chris Yates
Sent: Thursday, July 31, 2014 3:45 AM
To: Bélafi Zsófia; bldg-sim at lists.onebuilding.org
Subject: Re: [Bldg-sim] Input wanted: IES VE vs DesignBuilder

I've not used any of these for over 12 months. However, ...

DB is the easiest to model geometry in.

With IES it's a bit of a faff to get adiabatic surfaces into your model. You can mess around with turning layers on and off, but this affects your solar shading calc. In DB you can create adiabatic boundaries, whereas in ICE anywhere inside a building body that isn't connected to an adjacent surface is adiabatic (this is very convenient in my mind).

It's difficult to draw comparisons between speed of modelling. Whilst ICE doesn't have the snap tools that others have, I don't see this as a problem. Snaps are useful within the geometry paradigm of their respective programs - the geometry modelling paradigm in ICE is not really dependent on snaps. That said, it can seem a bit clunky. However, when you get beyond geometry, I find IDA to be much more 'in one place' than IES, refreshingly uncluttered and clipboard access to excel a superb feature.

The results viewer tool in IES (Vista) is a very good feature.

In terms of early stage stuff window area can be changed easily in DB and IES. I don't think ICE has this feature but it would be trivial for the developers to bring it in (they must already have the algorithms in place from their ASHRAE 90.1 tool).

I found gbxml import in IES to be sufficiently robust with enough 'healing' tools to make this a viable workflow. IES actually stores its 3d in a very similar arrangement to gbxml (3d polylines). It can also import IFC. ICE can import IFC and this also appears to be robust (Archicad does IFC, I think).

When you get down to HVAC, it is important to note that ICE is using a HVAC model even at a very simple level. This is not so in IES. If one wishes to use HVAC models instead of merely post processing zone simulation results you need to know what you're doing in ApacheHVAC. It has been a while since I've used the latter. However, I have found the connection between the IES model and the HVAC model to be fragile in the past.

In any of the tools, when you get more deeply into HVAC, you need a fair degree of expert knowledge. For example, in Energyplus (DB's engine) I found certain 'recipes' didn't work whilst in IDA you are quickly faced with a data dump indicating some matrix decomposition hasn't worked (whatever that is!). All the systems have basic templates to work from and if you don't wander too far from these you shouldn't end up in much trouble.

There will be modelling nuances between the tools: Computational ones, such as treatment of horizontal holes, or more functional ones, and even bugs that a user must be mindful of. I'm not going to go into this here however.

I hope this has been helpful.


On Thu, Jul 31, 2014 at 7:28 AM, Bélafi Zsófia <belafi.zsofia at abud.hu<mailto:belafi.zsofia at abud.hu>> wrote:
Dear Bldg Simers,

I work for an SME here in Europe that provides sustainability consultancy for many years now. We use IDA ICE for building energy modeling and we are planning to purchase another tool now.

Highlighted features of the new tool would be:

•         easy to learn/use for both architects and engineers

•         faster model building (compared to  IDA ICE)

•         supporting the early stage design decisions

•         compatible with ArchiCAD 3D import

According to the software descriptions and user guides both IES and DesignBuilder is perfect for these. I want to hear now your practical experience with them as there are always bugs and hidden errors in these tools.

Any comments are appreciated.

Many thanks!

Zsófia Bélafi
Junior Consultant

MSc. Architect
DGNB Consultant

ABUD I Advanced Building and Urban Design
Lónyay u. 29.
H - 1093 Budapest

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