Hello, I am currently trying to calculated Ds for the cooling condition for a project I an working on. Initially, I had the Ds value for each dual fan duct duct VAV unit set to 100%, but I was told by a colleague to change the value of Ds to be Ds = the minimum cooling flowrate of VAV/ the maximum cooling flowrate (Vdzd) of VAV. For example a room in the building has a max supply cfm of 210 and a minimum supply cfm of 63. Should Ds then be: Ds=63/210 = 30%? Or should I leave Ds as 100%? When I switched Ds from 100% to the equation I got the critical zone needs more ventialation error message.

Post a reply

Omar Elrawy

Green Building Consultant | Researcher

GreenA Consultants

LEEDuser Basic Member

38 thumbs up

Thu, 11/05/2015 - 13:42

A direct answer to your question is: set Ds = minimum flow (30%). I had a technical advice by the reviewer before to perform the calculations at the worst-case conditions, which was (in my case) to set most VAVs at Ds of 30%, and few VAVs that where designed with Ds of 40% (and I justified that by a narrative). Also the worst-case case is generally during heating mode, for me, I like to check both; heating and cooling modes.

Add new comment

To post a comment, you need to register for a LEEDuser Basic membership (free) or login to your existing profile.

You are currently logged in under an enterprise account

FAQs about IEQp1 :

Calculating Ds for LEED 62MZCalc

You rely on LEEDuser. Can we rely on you?

Add new comment