[Equest-users] LEED Question: Outdoor air intake flow for a VAV system..

[Maryanne Mason]

Hi Omar

 

Based on ASHRAE Std 62.1, the total outside air must be calculated at the
system level. If you then take the fraction of outside air supplied to the
system and multiply it by your system flow to each zone, you will get the
total outside air supplied to the zone. 

 

However, if you are trying to calculate the outside air requirements of the
zone, you need to calculate the space and occupancy requirements based on
the zone type (IE [# of occupants] * [cfm/occupant] + [square footage] *
[cfm / sq ft]), and then divide them by the ventilation effectiveness (IE
0.8 when supplying hot air from ceiling diffusers).

 

Please note that the total outside air required at system level is not the
sum of the individual zone requirements.

 

If you wish to get more information on this calculation, you can use the
following link:

 

http://www.ashrae.org/technology/page/132

 

and click on the standard 62.1-2001 addenda link. Then download addendum
"n".

 

This addendum has a good explanation of how the calculations should be done.
(Some of the occupancy tables have been updated since the addendum was
published, but the calculation method is still valid).

 

I hope I have clarified this issue somewhat.

 

Regards,

 

MaryAnne Mason

 

 

 

From: equest-users-bounces at lists.onebuilding.org
[mailto:equest-users-bounces at lists.onebuilding.org] On Behalf Of Omar
Katanani
Sent: Wednesday, December 01, 2010 2:51 AM
To: equest-users at lists.onebuilding.org
Subject: [Equest-users] LEED Question: Outdoor air intake flow for a VAV
system..

 

Dear all,

 

I have a LEED related question and I'd appreciate it if someone could help!

 

The LEED Reference guides show the method to calculate the outdoor air
intake flow (Vot) for the multiple-zone system (VAV). This Vot is for the
whole  <http://www.leeduser.com/glossary/14#term4654> AHU. How can I find
the Vot for each zone separately?

 

Many thanks!

Omar

 

___________________________

Omar Katanani
Sustainable Design Engineer

Email: omar at ecoconsulting.net

 

EcoConsulting (Lebanon)

Nahas Building, 4th floor

4 St-Maron Street / Georges Haddad Avenue

Postal Code: 2028 5806 SAIFI

Beirut, Lebanon

Tel:          +961 (0) 1 971 266
Mobile:    +961 (0) 3 045 045

 

EcoConsulting (UK) Ltd
28 Marshalsea Road
London, SE1 1HF
Tel:  +44 (0) 207 939 0989
Fax:  +44 (0) 207 939 0981

Website: www.ecoconsulting.net <http://www.ecoconsulting.net/> 

 

 

 

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