IEQp1- A3 Table Mechanical Ventilation 100%OA

Todor, In the 4.0 version of the EQ Prerequisite 1 LEED Form the room supply air flow is entered in the Vdzd (cfm) column. The 3.0 version of the Form doesn't have the Vdzd column. Try to use the 4.0 version. Beware that the LEED Form calculations will not match the ASHRAE tool ventilation rates. The LEED Form does not use the proper minimum zone ventilation efficiency to determine the system level ventilation efficiency. I have tested this several times, the EQp1 compliance is always slightly below what it should be. The v4.0 Form, interestingly enough, does calculate the EQ Credit 2, Increased Ventilation, properly using the proper minimum zone ventilation efficiency. The ASHRAE tool will not calculate this for you, you have to figure out the math yourself if you want to test what works and doesn't. I have also found that LEED Forms have issues when adding zones and systems. The system level values do not all update when you change a room type or the supply air rate. The only reasonable solution I have found is to download the LEED Form and use it in an offline mode. Print the forms and them upload a summary table for all of the systems with the LEED Form printed separately for each system. I merge the printed results into a single PDF to make the upload to LEED Online process easier.

Todor, I think I understand where your problem is coming from. It sounds like you are using a 100% OA unit to precondition and provide ventilation air to units that have some return air. If that is correct then you should not be using the 100% OA. The reason for this is that the 100% OA unit is not actually providing the ventilation air to the spaces (unless my assumptions are wrong), so essentially it is no different than if each unit were to have its own ducted OA intake. You should model each unit individually according to whether it is a single zone or multi-zone unit.

Todor, you should only have to choose "Mechanical Ventilation 100% Outside Air Unit". In the form (V4.0) appendix you can add AHU's and put in multiple zones for each AHU. The table will give you the required OA rate per zone and for the unit as a whole. If I understand correctly, some of the units are variable volume so you should input the minimum flow under normal operations for design flow. If the air is being used for space conditioning then you should use 0.8 for Ez since it will be supplying heat sometimes and it is not being returned. Once you fill out each unit's table and all of the zones per unit (in the appendix) you will be able to complete the first part of the form. I hope that helps.

Todor and I worked together on the question in this post. We decided to take the cautious route by strictly following the wording in the V4 of the form, which led us in the direction of providing both multiple zone and 100% outdoor air calculations. For closure I would simply like to add that we have received the review comments back from GBCI, as follows: "It is noted that two sets of calculations have been provided for each system, one set for multiple-zone recirculating systems (digression: note the form does not say "recirculation", but rather "Mechanical Ventilation Multiple Zone Unit") or single zone systems and one set for 100% outdoor air systems. For future projects, please ensure that only one set of calculations has been provided for each system, and that the most appropriate system type has been selected. For example, in this case, 100% outdoor air system calculations are all that is required to demonstrate compliance for the mechanically ventilated zones."

Hi, May i ask if this issue has been closed? If so, what is the result. Provide multi-zone, single zone and 100% OA? the reason why i asked, it's the same comments with my project. They've considered my AHU as Multi-zone since it was served multiple occupancy category although it only has 1 single thermostat (e.g. AC-2 composed of conf./mtg., restroom, breakroom, & storage room. So, i calculated VRP. The problem is the system gave me a red flag of " would need over 100% OA intake". This is not applicable to our project. Here are my question: 1. How can fix this red flag? Since 100% OA does not apply to our project? 2. Do i need to adjust somewhere? Please take note that i can only fill-up Az, Ez, Vdzd, Ds & design outdoor airflow? 3. Can i use both 62MZ calcs (for multi-zone) and VRP (for single zone)? 4. How come my IEQc2 for AC-2 was passed when reported as single zone, then failed when we reported as multi-zone. We provide the same values. thanks for any assistance/clarification on this. Susan