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Why is OpenStudio not suitable for residential projects?

asked 2016-01-23 11:33:28 -0500

allankey gravatar image

updated 2016-01-24 16:59:14 -0500

I am new to energy modelling and I am curious why Open Studio does not have any templates for residential buildings? Is it that residential models are not suitable? If so why not? Surely a building simulation program should be able to handle any building; type or size.

I have looked at BeOpt and the construction choices are limited and only suited to USA methods of construction.

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answered 2016-01-25 01:25:40 -0500

updated 2016-01-25 01:26:39 -0500

First, I agree with Amir that's it's EnergyPlus that has been lacking templates since its premises.

I actually think that any lack of feature is not the problem. You can very well use EnergyPlus to model a single family house.

In my opinion the lack of EnergyPlus templates is because it's always been pretty overkilled to use such a complex simulation program to simulate such a small and simple building type. I say simple because it has very few zones, it's usually envelope-driven, the HVAC is very basic and the HVAC controls are too.

It's a building type you can model pretty well if not better using a simple spreadsheet[1]. For existing buildings it's even more true.

Using E+ for that is like using a sledgehammer to crack a nut. And there's just too much overhead: the learning curve for EnergyPlus is pretty steep and scary.

GUIs such as OpenStudio are now helping on that front, and it's probably a matter of time before there's people creating these missing templates. Perhaps you can contribute to this effort!


[1] Michael Blasnik's "SIMPLE" model for example. Read up WSUEEP12-005 to see a study where they used both SIMPLE and BEOpt for example.

Here's another high level article. I like some of the quotes:

Blasnik reminds energy nerds that not every house needs to be a science project. “For energy retrofits, don’t waste your time doing simulations with dozens of inputs,” he said. “Do the obvious stuff. Just fix the leaky uninsulated house — don’t model it."

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Thanks very much for this!

allankey gravatar imageallankey ( 2016-01-25 05:39:27 -0500 )edit

Just because residential buildings are small does not make them simple to model. There are numerous areas where they are more complicated than commercial buildings, such as:

  • Ground coupling (homes can have combinations of slabs, crawlspaces, and basements)
  • Airflow modeling (stack/wind infiltration, mechanical ventilation, natural ventilation, and duct leakage)
  • Occupancy (hot water, lighting, plug loads, appliances, etc., usage)
  • Duct modeling
  • Articulated geometries (gables, dormers, roof types, walkout basements, split-levels, etc.)
  • Attic insulation tapering
shorowit gravatar imageshorowit ( 2016-01-26 20:22:21 -0500 )edit

Also, most modelers would certainly consider existing buildings to be more challenging to model than new homes. Why would you declare otherwise?

Existing buildings are much more sensitive to many of the above effects (like ground coupling, airflow modeling, and ducts) as well as complex effects like heat transfer through uninsulated or poorly insulated envelope cavities and radiation heat exchange.

shorowit gravatar imageshorowit ( 2016-01-26 20:25:37 -0500 )edit

Seeing the website you listed I understand how you could strongly react to what I said. I think we agree though... There's no reason not to use a better tool if you can afford to use it. E+ has been historically lacking on the user-friendliness.

I have made a shortcut/omission in my answer because I didn't want to write a dissertation, this isn't the place to do so (see my last comment too). Bottom line is that for the industry it doesn't make sense to spend 20 grand in a study to save a couple hundred dollars a year.

Julien Marrec gravatar imageJulien Marrec ( 2016-01-27 01:48:43 -0500 )edit

That may explain why for retrofits in EB houses, which are also most often driven by utility or government programs (e.g WAP, or MPP in NY state), it's usually the contractor who does the audit for almost free (or a stipend, like 500$, paid by EE program), does a simple calc/model (eg. TREAT for MP, or EA-QUIP for WAP) to apply for incentives and then implements that.

Blasnik is right in that sense: there's no sense in spending your entire budget studying and testing before and after. At some point you're better off using it to actually implement something.

Julien Marrec gravatar imageJulien Marrec ( 2016-01-27 01:52:27 -0500 )edit

answered 2016-01-23 12:24:25 -0500

It's not so much OpenStudio, it's EnergyPlus which has been missing models for a few important residential features ( most significantly, modeling of ducts in unconditioned spaces, e.g., attics) and equipment. However, we are actively working on this, most features (e.g., HPWH) are already in, and the remainder will be in by the September 2016 release.

I am less sure about support for non-US residential construction methods. What specific constructions are you looking for that are not supported?

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Also, the BEOpt team is actively working on residential support in OpenStudio via templates and Measures.

ljbrackney gravatar imageljbrackney ( 2016-01-23 15:56:01 -0500 )edit

Is there any update on the BEOpt OpenStudio integration? That would be a very useful feature.

Lincoln gravatar imageLincoln ( 2016-03-11 09:22:18 -0500 )edit

@shorowit is your best source for updates on this topic. The repo is here and under active development, although I believe it is currently private. I assume it will become public when the project reaches some level of readiness.

ljbrackney gravatar imageljbrackney ( 2016-03-11 10:13:51 -0500 )edit

We're still on schedule to have a passable duct model in the EnergyPlus fall release, with improvements in the subsequent two releases also. Some additional work on ground and basement modeling too.

__AmirRoth__ gravatar image__AmirRoth__ ( 2016-03-11 11:54:04 -0500 )edit

answered 2016-12-13 20:50:21 -0500

As a newbie to energy modeling I would concur with OP. My house project is not traditional and has aspects of both. I even plan to use an air to water Chiltrix heat pump system. The envelope and mix of flat and shed roofs, multiple zones, odd transitions in house forms, and semi commercial like fenestration.

I just want to accurately model the house myself since there are so many free tools out there. I am going to give Open Studio a run soon after wasting time on BEopt and eQuest. Don't get me wrong. Those are powerful simulation tools, but seem almost pointless given their limitations and options that are either focused only on commercial (eQuest) or too generic (BEopt).

If OS doesn't work then I'll try Simergy. Or Primero. Or start spending money with N++.

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Asked: 2016-01-23 11:33:28 -0500

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Last updated: Jan 25 '16