[Equest-users] Simplified Modeling

[Jason Quinn]

Your simplified and detailed model should agree quite closely. There
are at least two options I know of: 1. simplify zoning by combining
blocks into bigger zones, or 2. use multipliers to have the same size
zone counted many times.

Option 1: I've done something similar to your school with a large
office building (200,000 ft^2) had about 300 zones. In this case the
simplified model, with only 15 zones, (I used the default perimeter
and core zoning built into eQuest) matches the detailed model really
closely (3%)- in the relatively few comparative models I've done the
simplified model is always with 10% of the detailed model if I use the
same systems, and match window %, shell areas etc. fairly closely.
Thinking about this in more detail my models have always been fairly
open plan offices but if your zone temperatures are all controlled to
the same then they should match pretty well with a simplified model
given roughly the same shell/loads.

Option 2: I work Green Star here in NZ so my LEED knowledge is only
book and chatter but I've heard you can combine spaces (per ASHRAE
90.1) with similar orientation/ size etc. Nick Canton (see the
archives - pretty sure it was him) wrote a bit about combining lots of
hotel rooms into just a few blocks with lots of multipliers. 100's of
zones down to 30 or so.

Jason

On Thu, May 24, 2012 at 9:19 AM, Matt Clough <mclough at kme-inc.com> wrote:
> Ok equesters,
>
>
>
> I imagine my problem has something to do with my understanding of thermal
> blocks, so I wanted to get some feedback from other modelers.
>
>
>
> Currently, I’m performing a LEED analysis of a 166,000 f^2 school building.
> I have created a space for every terminal box to accurately represent that
> system.  Unfortunately, this works out to one or two hundred spaces (I
> haven’t actually counted) and a very large model that takes a lot of time to
> simulate.
>
>
>
> Is it possible for me to create a model that represents each HVAC zone?  I
> have created a quick set of shells and air-side systems and a preliminary
> simulation reports almost double the energy usage as the detailed model.
>
>
>
> If I represent the entire HVAC zone as one space (one eQuest zone), what is
> the best approach to represent the terminal units?  It seems to me that
> using the PIU option would be like having one vav box serving an enormous
> room.  While that’s not the reality of the situation, is that good enough
> for simulation?
>
>
>
> I suppose I will report back after I tinker with this some more.
>
>
>
> Regards,
>
> Matt Clough
>