No contaminant area-related-sources

No it is not. You need to include the ventilation requirements for Rp and Ra.

LEED has traditionally not allowed the IAQ procedure for this prerequisite. Although there are ASHRAE papers showing that the IAQ procedure results in lower energy use and better indoor air quality, this information has fallen on deaf ears at USGBC. LEED 2009 Text: “Meet the minimum requirements of Sections 4 through 7 of ASHRAE Standard 62.1-2007, ... CASE 1. Mechanically Ventilated Spaces Mechanical ventilation systems must be designed using the ventilation rate procedure or the applicable local code, whichever is more stringent.” Note that this requirement specifically calls out the ventilation rate procedure. The following CIR only technically applies to LEED 2.2. I'd love to see someone post a CIR asking if it is still applicable to LEED 2009 and LEED V4, but I expect that the answer is yes, it does apply and no, they won't allow the IAQ procedure. "LEED Interpretation MPR/Prerequisite/Credit: IEQp1: Minimum Indoor Air Quality Performance Posting Date: 5/15/2007 ID Number: 5053 Primary Rating System: New Construction v2.2 The CIR is inquiring if the IAQ Procedure, as described in Section 6.3 ASHRAE Standard 62.1-2004, can be used in place of the Ventilation Rate Procedure of the same Standard to document compliance with the requirements of this prerequisite. The Ventilation Rate Procedure methodology found in Section 6.2 of ASHRAE 62.1-2004 is the required approach in EQp1, since it is prescriptive and therefore more straightforward to apply. The Ventilation Rate Procedure is based on contaminant sources and source strengths that are typical for common space types listed in the Standard. The Indoor Air Quality (IAQ) Procedure methodology found in Section 6.3 of ASHRAE 62.1-2004 and proposed by this project team is performance-based and relies on identification of contaminants of concern, sources for those contaminants, concentration targets, and perceived acceptability targets. The project-specific nature of the IAQ procedure methodology makes it less commonly used and more difficult for USGBC to evaluate. Therefore USGBC cannot allow its use to show compliance with LEED NC v2.2 EQp1. Please note that the intent behind this prerequisite is to encourage designers to take the most stringent and conservative prescriptive approach to providing fresh air. The language of the prerequisite asks designers to compare the rates recommended under Ventilation Rate Procedure with that required by their local code and to pick the most stringent. As for the project team's legitimate concern with energy efficiency, the "additive" Ventilation Rate Procedure adopted in the ASHRAE Standard 62.1-2004 reflects concerns for energy consumption with elevated ventilation rates. The recommended rate under the Ventilation Rate Procedure in ASHRAE Standard 62.1-2004, in many important occupancy types and projects can result in lower ventilation rates than those required by the earlier version of the Standard - Standard 62.1-2001."

The IAQ procedure is absolutely allowed to be used if done correctly. The problem is that to correctly use it, you need to have an active contaminant reduction system such as gas phase filtration. Documenting the use of an assumed lower source material to meet this procedure is more than likely going to be rejected. For your second question, the answer is that you should use actual occupancy and do not neglect the Rp variable. If you feel that the volume is so large that it dilutes the contaminants then do a short-term condition based on volume (paragraph 6.2.6.2), however I think you will find that it will not benefit you for such a small volume.

Andrew - Are you sure that this statement is correct, based on an actual LEED reviewer accepting the IAQ procedure on one of your LEED projects? For in the past they have categorically rejected the IAQ procedure (as of LEED 2.2) as I stated above, in CIR ID Number: 5053. I am really hoping you are correct, because I have an Engineer really wanting to use the IAQ procedure, but everything we find in the CIR database points to rejection.

Lawrence, I have never attempted to use the IAQ procedure on a LEED project. My comment is based on someone at American Air Filter telling me that they have used their gas phase filtration products to achieve the prerequisite and that the IAQ procedure would comply with LEED v3.0 since it is an acceptable means of ventilating a building according to ASHRAE 62.1-2007. If I were to attempt this method I would submit a CIR and have a very well documented case for contaminant control. The documentation in 62.1 is very weak and I would not recommend using it alone. I would not assume that it is impossible based on a 6 year old CIR from a previous version of LEED.