Forum discussion
CI-2009 IEQp1: Minimum IAQ Performance
Do you have a definition for Ds(%)? ASHRAE 62.1 does not have such a variable. There is a D for diversity, which seems to be the inverse of this Ds based upon experimentation. Can anyone advise?
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Is outdoor air quality testing required in a space using natural ventilation?
What options are available to projects outside the US to meet this prerequisite?
Can LEED 2009 projects elect to follow ASHRAE 62.1-2010 for this prerequisite?
Which units should be included in the calculations for this prerequisite?
Roger Chang
Principal, Energy and Engineering LeaderDLR Group | Westlake Reed Leskosky
LEEDuser Expert
398 thumbs up
November 30, 2012 - 12:08 pm
D is the same as Ds. The s is a subscript to represent diversity at the system level. D is described in Chapter 6 of ASHRAE 62.1.
Dylan Connelly
Mechanical EngineerIntegral Group
LEEDuser Expert
472 thumbs up
December 4, 2012 - 7:00 pm
Nena/Roger,
I think there is some confusion here. D is not the same as Ds.
D=Diversity. Either in regards to the population served by the system vs FTE or the sum of all your zone maximum supply quantities vs your system capacity.
Example:
Your office spaces has a ventilation design capacity of 50 people and your conference rooms have a design capacity of 50 people. But your FTE is only 50 people. Your population D=50%. This reduces your outdoor air intake requirements.
Ds=Percentage of total design airflow rate at conditioned analyzed.
Example.
You have a VAV system with a 50% turn down for heating mode. Ds = 50%. Ds is typically the turn down at the terminal (for the design condition). For a VAV system, it is typically between 30-50%. For a constant volume system, Ds=100%. A lower Ds will give you a lower Ev coefficient, resulting in higher OA intake requirements.
On LEEDOnline, go to the main page for IEQp1. Then on the right, under quick links is a link to "Credit Resources." Download the "62MZCalc" excel file. Although it may confuse you more, at least there are some directions and definitions in that file.