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"High-level" inputs vs. a Full-Blown Model

asked 2017-06-30 12:20:16 -0600

Melissa B.'s avatar

updated 2017-07-03 06:32:39 -0600

I routinely hear modelers talk about doing a "high-level" model versus a more detailed one. What is the difference? And how does someone do one without doing the other?

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Hi @Melissa B. did you intend to include OpenStudio as a tag to your question?

Aaron Boranian's avatar Aaron Boranian  ( 2017-06-30 13:23:11 -0600 )edit

Yes. Is there some reason I shouldn't have?

Melissa B.'s avatar Melissa B.  ( 2017-06-30 15:23:41 -0600 )edit

You had just left the text "OPEN STUDIO" in the question instead of as a tag like high-level and model. I've made the change.

Aaron Boranian's avatar Aaron Boranian  ( 2017-06-30 15:49:59 -0600 )edit

Thanks, everyone, for the answers. 'Super-helpful.

Melissa B.'s avatar Melissa B.  ( 2017-07-03 06:53:19 -0600 )edit

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answered 2017-06-30 23:01:04 -0600

High level models infer the bulk of the simulation engine's requisite inputs to approximate a building. A good example is the DOE prototype Measure, which takes building type, vintage, and climate zone as inputs. The Measure then uses data from the OpenStudio Standards Gem and a set of heuristics (based on ASHRAE 90.1 modeling guidelines) to create the thousands of lines of input data needed by EnergyPlus. Detailed models will have many more of those inputs specified by hand to create a model that more closely represents a specific building. Tools like DOE's Commercial Building Asset Score fall somewhere in the middle, requiring more inputs than the prototype Measure, but fewer than the detailed model. It comes down to what kind of problem you're trying to solve and how much fidelity you expect as to how much detail you need.

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DOE offers free training webinars for Asset Score on a regular basis. Basic training on July 6, 2017: https://register.gotowebinar.com/register/4669211750629252867 Advanced training on July 20, 2017: https://register.gotowebinar.com/register/1496575346728255491

Asset Score allows users to download the OpenStudio model file (.osm), so it can be useful as a starting point for a more detailed model.

Matt Huffman's avatar Matt Huffman  ( 2017-07-05 10:21:28 -0600 )edit
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answered 2017-07-03 06:42:30 -0600

updated 2017-07-03 06:43:44 -0600

Another example might be a "shoebox" model. In early stages of the development of a new construction building (schematic design stage), it is often used. The design has just started, so there's a lot of uncertainty and things will change often and a lot. It is impossible (and wouldn't make sense anyway) to create a detailed model. Yet there are questions for which simulation can and should be used.

You might create such a model by inputting its general shape and using a perimeter/core layout (5 zones per floor, all of "Office" type for example), use ribbon windows to match a window to wall ratio, and use fully autosized systems. It will then be used to determine high-level orientations for the design, such as options for the massing of the building, how much window to wall ratio you want, and the general HVAC strategy to be employed (for eg you might want to see the high level difference between using a chiller + cooling tower versus a VRF, etc).

Later on, when the design is more narrowly defined and things aren't expected to change that much, you will want to refine your model to more closely match reality. You'll draw the windows in their actual location, zone the building like it will be in real life (open office, closed offices, mechanical rooms, corridors, etc), and input the HVAC systems per the MEP's design (use the actual design values, etc).

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Asked: 2017-06-30 12:20:16 -0600

Seen: 420 times

Last updated: Jul 03 '17