FW: Apparent error on ASHRAE 90.1-2007 (and perhaps 2010)

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Dear forums,
I think I have discovered an error in the SI version of ASHRAE 90.1 regarding fan power for Baseline Systems 1 & 2. I sent the message below to ASHRAE, but then thought, "Perhaps someone else has also noticed this and received some guidance from ASHRAE". Regardless, if it is actually an error, it's worth mentioning to all of you so that you can be aware of it.
Please let me know if you are aware of this, and how you have dealt with the discrepancy. My plan is to use the IP formula because it allows more fan power :).

James V Dirkes II, PE, BEMP, LEED AP

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Joined: 2011-10-02
Reputation: 203

Fabiano,
It's encouraging that they noticed something, however I don't think the math works properly with the formula you sent.
(SI): (1 L/s * 1000) * .14 = 140 W (This is 1 m3/s)
(IP): 2118.64 cfm * .3 = 636 W (This is also 1 m3/s)

James V Dirkes II, PE, BEMP, LEED AP

James V Dirkes II, PE's picture
Joined: 2011-10-02
Reputation: 203

Forgot to say:
A factor of .636 seems to work better.
(SI): (1 L/s * 1000) * .636 = 636 W (This is 1 m3/s)
(IP): 2118.64 cfm * .3 = 636 W (This is also 1 m3/s)

James V Dirkes II, PE, BEMP, LEED AP

James V Dirkes II, PE's picture
Joined: 2011-10-02
Reputation: 203

Hey Jim,

I think you are right.

0.3 x CFM = W

0.3 x (L/S) /0.472 = W

thus

0.636 x L/S = W

Thanks,

Marcin Polak, LEED AP BD+C

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Joined: 2013-04-26
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