[Bldg-sim] How long it takes for energy modeling? HME

Tim Dion TimD at Hargis.biz
Mon Apr 6 11:53:46 PDT 2009


Sherie - I'll do my best. The majority of our energy models are for the sole purpose of performing an Energy Life Cycle Cost Analysis for schools and other government funded buildings here in Washington State. These reports are used to aid the owner in making decisions regarding envelope design, HVAC systems, lighting controls and power density, etc. that best suit their needs.

1. SD - Providing we have adequate building layouts from the Architect.

2. Rules of thumb system sizing and Industry Standards. If equipment schedules are completed we use those.

3. eQuest.

4. We normally build 1 model in the design wizard that includes all systems to be studied in the report (normally 4 systems includeing an ASHRAE G baseline). Then each system gets modeled seperately using this main model as a starting point. Normally it takes 40 hours to get this starting model built with all utility rates, schedules, envelope parameters, etc. established for the project.

5 & 6. Another 40 - 60 hours is spent developing the 4 seperate models for HVAC system types to be studied, fine tuning each model, and anaylizing the outputs.

7. If you start a project in SD you have to understand that it is a snap-shot in time. How it compares to the CD varies greatly.

We are also writing a report with a very specific layout/guideline to follow. The hours for writing the report are not included here.

As other people have stated hours can vary greatly but on average we are able to complete our models/simulations within these ranges.

________________________________
From: bldg-sim-bounces at lists.onebuilding.org [mailto:bldg-sim-bounces at lists.onebuilding.org] On Behalf Of Sherie E. Hensley
Sent: Wednesday, April 01, 2009 10:46 AM
To: bldg-sim at lists.onebuilding.org
Subject: [Bldg-sim] How long it takes for energy modeling? HME


I have done several energy models over the last few years using Trane Trace.  I have heard others (typically from those who don't have experience with energy modeling) say "it only takes a day" to create an energy model and get results.

I am trying to get a better understanding of how long it takes others to complete an energy model.  I realize there are many factors involved and length of time can vary drastically given the complexity of the project.

For an xxx sq ft project with xxx systems:

1.  What phase are you starting the energy model - SD, DD, CD?

2.  What information are you starting with - load results from another program, rules of thumb for system sizing, etc?

3.  What program are you using?

4.  How long does it take to build the proposed model?

5.  How long does it take to build the baseline model (per ASHRAE 90.1-2004, Appendix G)?

6.  How long does it take to calculate the results from the energy simulation program?

7.  If you have started a projected in the SD phase, how detailed is the input information you use?  How do the results compare to the energy model developed in CD - within 10%?

Any information you can provide would be helpful.

Thanks,

Sherie Hensley
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