Comments on: How Accurate Is REM/Rate as an Energy Modeling Tool?

By: Martin Holladay

Martin Holladay — Fri, 30 Mar 2012 18:52:51 +0000

I’ve just written a blog with
I’ve just written a blog with more information on Michael Blasnik’s analysis of REM/Rate accuracy. Here’s the short version: the software isn’t particularly accurate for older buildings. Read more here:
http://www.greenbuildingadvisor.com/blogs/dept/musings/energy-modeling-isn-t-very-accurate 

By: Hunter

Hunter — Fri, 29 Jul 2011 04:36:44 +0000

I just wish the user
I just wish the user interface and report outputs were better. It feels like the reports should be printed on a dot matrix printer, and tear the edges off, remember that?

By: Allison Bailes

Allison Bailes — Thu, 28 Jul 2011 14:58:06 +0000

David B.:
David B.: Thanks for the link! Interesting data and results that illustrate where REM/Rate doesn't work as well.

By: David Butler

David Butler — Thu, 28 Jul 2011 10:46:19 +0000

opps… here’s the link:&amp
opps… here’s the link:
http://bit.ly/q7cqfO

By: David Butler

David Butler — Thu, 28 Jul 2011 10:45:28 +0000

Here's a link to Dave Robert
Here's a link to Dave Robert's slideshow from 2008 RESNET Conference where he describes several previous studies on REM accuracy.

By: Allison Bailes

Allison Bailes — Thu, 28 Jul 2011 01:00:41 +0000

Christopher
Christopher: You're absolutely right. When fixing older houses, energy savings is only one of the benefits - comfort, durability, and indoor air quality are often more important to homeowners.

John P.: You're welcome!

By: John Poole

John Poole — Wed, 27 Jul 2011 20:03:07 +0000
True, no curve fitting in
True, no curve fitting in those diagrams, just ideal curves. But you alluded to a best-fit curve in the first case being close to the ideal, and all that empiricist-speak got me excited. Thanks for the link. I will definitely go check it out! :-)

By: Christopher Cadwell

Christopher Cadwell — Wed, 27 Jul 2011 19:50:49 +0000
When I model a retrofit and
When I model a retrofit and downsize the ac unit and put the ducts in the thermal boundary, my experience with rem is that it way undershoots the actual savings.

So then do I use it and tell the homeowner to ignore the projection because well really do a lot better than what it says? No. Too much information while trying to sell a retrofit. I stopped using Rem for projecting cooling savings just for this reason. Also I almost never sell a retrofit for energy savings, but rather for "let's do it the way it's supposed to be done."

Maybe rem is ok for new homes.

I still think baseload factors are easy to adress and don't need modeling. Beyond that use the Man JDS to calculate and design the home and project energy costs of comfort.

It may take decades until we get designers to do HVAC right consistently and we see hvac companies install perfectly sized duct and ac systems. Until then I agree that rem is the best chance we have for now for the fray of the professionals.

Just my opinions. Not facts.

By: Allison Bailes

Allison Bailes — Wed, 27 Jul 2011 19:39:12 +0000
Lance:
Lance: User friendliness, suitability, and features are definitely important when you're choosing software for energy modeling. I also run REM/Rate through Parallels on a Mac, so I feel your pain there.

John P.: I'm glad you're as excited by the data as I am. I hate to disappoint you, though, but there's no curve fitting here. I did mention it, but there's none shown above. Maybe I can get some in with the triple integration article for you. There are already plenty of options for energy modeling out there now. Have you seen this page: DOE Building Energy Software Tools Directory? You're gonna think you died and went to heaven!

By: John Poole

John Poole — Wed, 27 Jul 2011 18:38:07 +0000
Finally! Data and curve
Finally! Data and curve-fitting. I don't see any triple integrals yet, but I figure those can't be too far behind!
Seriously, though, I enjoyed this article, Allison, and will make a study of the Houston paper.
There's no doubt, based on what you've cited, that REM/Rate is highly accurate, but I would tend to agree with Lance's more general criticisms. Also, as home energy modeling gains more traction over time, it wouldn't be too surprising if a few open software initiatives providing similar analysis/modeling/reporting tools begin to emerge.