Using ASHRAE 90.1-2004 Models to Estimate 2007 Edition Reductions

If you read this post within the next five minutes you'll get our Super Bonus 2030 Challenge Code Equivalents Included free of charge!*

I've been helping our project architects put together a federal proposal right now. The DoD requires a detailed narrative based on ASHRAE 90.1-2004 to show compliance with the Energy Policy Act of 2005's 30% reduction requirement, but they also require us to complete a proposed LEED-NC 2009 checklist which bases points on the new ASHRAE 90.1-2007 standard.

I understand that 2007 is more stringent, but understandably, the mechanical engineer doesn't want to rework the entire baseline model for a project we haven't even been awarded yet! I decided to see if I could find any rough estimates for this online, and sort of succeeded thanks to the 2030 Challenge.

Not this one

Wrong challenge... as if anyone would want to drink Pepsi anyway.

Figuring out if you've complied with the 2030 Challenge's interim requirements is no small task, so Mr. Mazria got a few smart folks together to create a document that shows what you have to do using existing codes and standards to meet the then relevant 50% reduction in energy use over 2003 averages. Unsurprisingly, they called the document "Meeting the 2030 Challenge Through Building Codes.

Get to the Conversion Already

Luckily for us, this document features both the 2004 and 2007 ASHRAE 90.1 equivalents, and from there we can draft a very rough approximation of a conversion factor. The folks over at the 2030 Challenge wrote that exceeding the 2004 standard by 30%, and exceeding the 2007 standard by 25%, are both roughly equivalent to the interim 50% goal, so logic would dictate they felt that these are also roughly equivalent to each other.

So... running the numbers we see 25 / 30 = .8333 multiplier if you're using a 2004 reduction you wish to translate to 2007. If for some reason you needed these in reverse 30 / 25 = 1.2 multiplier to take a 2007 reduction and translate it to the 2004 standard.

I should point out that this factor should probably be taken with a grain of salt. The complexities of the modeling process, namely that the baseline is a shifting target dependent on system selection, would indicate that this is at best imprecise and at worse horrendously inaccurate. At the moment though, I suspect some of you could use such a tool for estimating points early in the design process.

If any of you modelers out there wish to tell me how wrong I am, please do so by leaving a comment for all to see!

*Technically it's always free of charge, and I've recently come to learn all Architecture 2030 publications are free to the public.**

**[EDIT 01/25/10] I originally had a "A $69.99 value!" listed as the footnote as a joke, but some alert folks over at Architecture2030 did not want readers to get the impression that Architecture 2030 charges for their publications. You'd think a non-profit institution like the USGBC would be wise to consider a similar strategy!


Elaine Barnes said...

I used a similar analysis to set our energy savings goals for the Ohio School Facilities Commission projects that register for certification under LEED Version 3. We also have developed standardized operating schedules for our engineers to use for comparison to our current goal of annual energy consumption of 35kBtu/sf. Schedules, set back temps and plug loads can, of course, dramatically effect this number. With numbers reaching 250 projects, we will have great data for the school design community.

Elaine Lipman Barnes, LEED AP
Green School Program Manager
Ohio School Facilities Commission
twitter: greenschoolsoh

Unknown said...

I actually prefer Pepsi to Coke. Is that so wrong?!

joelmckellar said...

Yes... You're a terrible human being dave.

Anonymous said...

Do we need a Coke summit to settle things?