Fan energy fundamentals - Appendix G models

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In this previous thread I am not sure if anyone answered my question. Even if it was answered I can't find it so I'm hoping someone could help.

For a LEEDv9 model (90.1 2007) we use the Appendix G VAV fan curve for the base case model. However, 2007 requires SP reset in Can we used the EDR Guide (good SP Reset) curve for the proposed model? Or are we to use App G curve for both cases?

In the past I've used the Good SP Rest for the Proposed but I'm not sure if I've been gaming the system.


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Melissa P. Crowe, LEED AP
Project Engineer
Engineered Solutions, Inc.
6 Union St, Natick MA 01760
508.647.9200 x225 (P) l 508.652.1936 (F)
MCrowe at

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Melissa Page Crowe's picture
Joined: 2011-09-30
Reputation: 1

That was a good thread wasn't it =)? For those interested the thread discussion took place off and on in 2011 and 2012 - I've attached for easier reading (the earlier thread includes many visual curve illustrations).

Guidance here remains FUZZY (to my knowledge & understanding)!

I would clarify/nitpick that itself does not require SP reset, rather it specifies how pressure sensors are to be installed when they are in play. The preceding section introduces the idea that part-load control is required, but only for 10hp and larger motors. You may be overly conservative in attempting to apply SP reset to your baseline.

That said, if your proposed design employs good static pressure reset control strategies, I think you are within acceptable territory to differentiate that from the prescribed baseline VAV curve (invoking an exceptional calculation and providing your logic via narrative/writeup), but therein lies the rub: how can you marry the two when the prescribed baseline curve does not appear to recognize realities like motor or VSD losses?

The easy thing to do would be to just match curves and move on, but you're posting in this forum so of course that isn't the answer you're looking for is it ;)?

If I were trying to solve this for a LEED job, I would start with the prescribed baseline curve, and build upon that in a logical fashion, citing and including the EDR guidelines along the way, to come up with an apples-to-apples equivalent curve representative of the "good" practices which result in real world energy savings through proper implementation of SP reset strategies. Then maybe I'd send the report to Popular Science to get published and have a few strangers buy me a beer at the next energy modeling conference... right? right?

Not a lot of direct help here, but assurance that you are on the cutting edge and blazing new paths, as far as I can tell ;).

Best of luck!


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Nick-Caton's picture
Joined: 2011-09-30
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We're doing this same thing for a LEED model that's going to be submitted towards the end the year.

The baseline uses that standard ASHRAE fan curve, and the proposed uses a curve developed based on the "Good SP Reset" curve from the EDR guide.

We did do an inquiry with GBCI to determine if this approach was acceptable and they said it was, but the official review will have final say.

Sounds like you (we) are on the same right track.


Fred Betz PhD., LEED AP (r)BD&C
Senior Sustainable
Systems Analyst

5802 Research Park Blvd. | Madison, WI 53719

P: 608.236.1175 | F: 608.238.2614
fbetz at |

Fred Betz's picture
Joined: 2011-09-30
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Thanks for the information! In the past I have used this approach successfully for a LEED project..... but it was years ago when 90.1 2004 was the reference. So I wasn't sure if it would still stand.

Yet somehow no matter what it always seems a "cross your fingers and hope" as far as the opinion of the reviewer.

It is good to have company on the camino.
Good Luck and Thanks Again

Melissa Page Crowe's picture
Joined: 2011-09-30
Reputation: 1