Our building is fully occupied by the same company, so all the floors have similar open space layout, except for enclosed managers or small meeting rooms.
There´s an outside air intake in each AHU level. Each floor is served by one AHU, that provides a mixture of outside air with return air, on a constant volume. There are no VAV´s, no dampers and no different zones in our ventilation plenum.
Since the floors are mostly open space, have no critical zones (bigger meeting rooms, in the last floor, are served by different AHUs), and are all of the same type (office space), is it wrong to consider it a single-zone system, and measure the intakes only in the AHU level? Or should I consider it a multizone and go through all the VRP calculations?
Dave Hubka
Practice Leader - SustainabilityEUA
LEEDuser Expert
528 thumbs up
March 14, 2013 - 9:36 pm
Outside air measurements are required at the system level. In your case it would be at each AHU. The LEED online template calculator (the appendix section of the template form) is for a constant volume unit that serve a single room. The 62MZ calculator is for all other types. You'll most likely be required to complete a 62MZ calculator and verify the OA at each AHU.
Hope this helps
Dave
Guilherme Ramos
12 thumbs up
March 15, 2013 - 1:07 pm
Thank you, Dave, but maybe I was unclear. The question is more about multi zone and single zone systems definition.
When LEED refers to multi or single zone UNITS, they mean the same definition of ASHRAE ventilation ZONES?
I´m sure my system is a single zone, it´s not common to have multiple zone systems in Brazil. Although in each floor we have different rooms and offices, served by the same AHU, i think my approach in the template should be more for Appendix 1 "Mechanical Ventilation Single Zone Unit", is it right?
Thank you!
Dave Hubka
Practice Leader - SustainabilityEUA
LEEDuser Expert
528 thumbs up
March 15, 2013 - 1:37 pm
Hello Guilherme.
Multiple Zone Unit describes an AHU that serves more than one room.
Single Zone Unit describes an AHU that serves one room.
Systems with local recirculation and/or multiple recirculation paths (such as systems with fan-powered terminal units) should use the 62MZ calculator.
If you have a constant volume AHU that serves more than one room, and no terminal units within the system, you can use the Multiple Zone Unit calculator on the LEED online template. (from your description, i believe this to be the path you should choose)
If you have a constant volume AHU that serves only one room you will be required to use the Single Zone Unit calculator on the LEED online template.
If you have a system with local recirculation and/or multiple recirculation paths you will be required to use the 62MZ calculator.
For example, an AHU that serves (1) office and (1) conference room, this is defined as a Multiple Zone Unit (regardless if the system includes local recirc/terminal units). If an AHU serves only (1) office, and no other room, than this is considered a Single Zone Unit.
Hope this better clarifies.
Paula Hernandez
MRS.PAH&A
85 thumbs up
October 24, 2023 - 10:43 am
Hi Guilherme and Dave,
I am following this posts, and they are very usefull regardint ventilation system interpretation.
I have the following schenario:
Thank you!
Dave Hubka
Practice Leader - SustainabilityEUA
LEEDuser Expert
528 thumbs up
October 24, 2023 - 10:55 am
In the scenario you describe:
Er = 1
zone discharge airflow = zone primary airflow.