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<P><FONT SIZE=2>Thanks Maryanne!<BR>
<BR>
By reading through 62.1 2007 section 6.2.5 (Ventilation rate procedure for Multiple Zone Recirculating Systems), a detailed procedure is given to calculate the Outdoor design air flow for each Air Handling Unit Vot.<BR>
This Vot is, as you said, greater than the sum of each zone's outdoor rate.<BR>
<BR>
The question is:<BR>
How do I correct each zone's outdoor air rate?<BR>
<BR>
A possible simple way is to check the ratio of Vot divided by the sum of each zone's outdoor rate. Assume this number is, lets say, 1.1<BR>
<BR>
I can then multiply each zone's outdoor air by this ratio (1.1) to get the new corrected value.<BR>
This is a proposed method based on some logic.<BR>
<BR>
Any suggestions?!<BR>
<BR>
Thanks!<BR>
Omar<BR>
<BR>
___________________________<BR>
<BR>
Omar Katanani<BR>
Sustainable Design Engineer<BR>
Email: omar@ecoconsulting.net<BR>
<BR>
<BR>
EcoConsulting (Lebanon)<BR>
Nahas Building, 4th floor<BR>
4 St-Maron Street / Georges Haddad Avenue<BR>
Postal Code: 2028 5806 SAIFI<BR>
Beirut, Lebanon<BR>
Tel: +961 (0) 1 971 266<BR>
Mobile: +961 (0) 3 045 045<BR>
<BR>
<BR>
EcoConsulting (UK) Ltd<BR>
28 Marshalsea Road<BR>
London, SE1 1HF<BR>
Tel: +44 (0)207 939 0989<BR>
Fax: +44 (0)207 939 0981<BR>
Website: www.ecoconsulting.net<BR>
<BR>
<BR>
<BR>
-----Original Message-----<BR>
From: Maryanne Mason [<A HREF="mailto:maryanne.mason@ausencosandwell.com">mailto:maryanne.mason@ausencosandwell.com</A>]<BR>
Sent: Wed 12/1/2010 7:46 PM<BR>
To: Omar Katanani<BR>
Cc: equest-users@lists.onebuilding.org<BR>
Subject: RE: [Equest-users] LEED Question: Outdoor air intake flow for a VAV system..<BR>
<BR>
Hi Omar<BR>
<BR>
<BR>
<BR>
Based on ASHRAE Std 62.1, the total outside air must be calculated at the<BR>
system level. If you then take the fraction of outside air supplied to the<BR>
system and multiply it by your system flow to each zone, you will get the<BR>
total outside air supplied to the zone.<BR>
<BR>
<BR>
<BR>
However, if you are trying to calculate the outside air requirements of the<BR>
zone, you need to calculate the space and occupancy requirements based on<BR>
the zone type (IE [# of occupants] * [cfm/occupant] + [square footage] *<BR>
[cfm / sq ft]), and then divide them by the ventilation effectiveness (IE<BR>
0.8 when supplying hot air from ceiling diffusers).<BR>
<BR>
<BR>
<BR>
Please note that the total outside air required at system level is not the<BR>
sum of the individual zone requirements.<BR>
<BR>
<BR>
<BR>
If you wish to get more information on this calculation, you can use the<BR>
following link:<BR>
<BR>
<BR>
<BR>
<A HREF="http://www.ashrae.org/technology/page/132">http://www.ashrae.org/technology/page/132</A><BR>
<BR>
<BR>
<BR>
and click on the standard 62.1-2001 addenda link. Then download addendum<BR>
"n".<BR>
<BR>
<BR>
<BR>
This addendum has a good explanation of how the calculations should be done.<BR>
(Some of the occupancy tables have been updated since the addendum was<BR>
published, but the calculation method is still valid).<BR>
<BR>
<BR>
<BR>
I hope I have clarified this issue somewhat.<BR>
<BR>
<BR>
<BR>
Regards,<BR>
<BR>
<BR>
<BR>
MaryAnne Mason<BR>
<BR>
<BR>
<BR>
<BR>
<BR>
<BR>
<BR>
From: equest-users-bounces@lists.onebuilding.org<BR>
[<A HREF="mailto:equest-users-bounces@lists.onebuilding.org">mailto:equest-users-bounces@lists.onebuilding.org</A>] On Behalf Of Omar<BR>
Katanani<BR>
Sent: Wednesday, December 01, 2010 2:51 AM<BR>
To: equest-users@lists.onebuilding.org<BR>
Subject: [Equest-users] LEED Question: Outdoor air intake flow for a VAV<BR>
system..<BR>
<BR>
<BR>
<BR>
Dear all,<BR>
<BR>
<BR>
<BR>
I have a LEED related question and I'd appreciate it if someone could help!<BR>
<BR>
<BR>
<BR>
The LEED Reference guides show the method to calculate the outdoor air<BR>
intake flow (Vot) for the multiple-zone system (VAV). This Vot is for the<BR>
whole <<A HREF="http://www.leeduser.com/glossary/14#term4654">http://www.leeduser.com/glossary/14#term4654</A>> AHU. How can I find<BR>
the Vot for each zone separately?<BR>
<BR>
<BR>
<BR>
Many thanks!<BR>
<BR>
Omar<BR>
<BR>
<BR>
<BR>
___________________________<BR>
<BR>
Omar Katanani<BR>
Sustainable Design Engineer<BR>
<BR>
Email: omar@ecoconsulting.net<BR>
<BR>
<BR>
<BR>
EcoConsulting (Lebanon)<BR>
<BR>
Nahas Building, 4th floor<BR>
<BR>
4 St-Maron Street / Georges Haddad Avenue<BR>
<BR>
Postal Code: 2028 5806 SAIFI<BR>
<BR>
Beirut, Lebanon<BR>
<BR>
Tel: +961 (0) 1 971 266<BR>
Mobile: +961 (0) 3 045 045<BR>
<BR>
<BR>
<BR>
EcoConsulting (UK) Ltd<BR>
28 Marshalsea Road<BR>
London, SE1 1HF<BR>
Tel: +44 (0) 207 939 0989<BR>
Fax: +44 (0) 207 939 0981<BR>
<BR>
Website: www.ecoconsulting.net <<A HREF="http://www.ecoconsulting.net/">http://www.ecoconsulting.net/</A>><BR>
<BR>
<BR>
<BR>
<BR>
<BR>
<BR>
<BR>
<BR>
</FONT>
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