[Equest-users] LEED Baseline secondary HVAC system

[Maria Karpman]

I would argue that residential system type (PTAC/PTHP) should be applied to
the entire multifamily building. The heading of the first column in Table
G3.1.1A is Building Type, not Space Type. The note below the table reads
"Residential building types include dormitory, hotel, motel, and
multifamily..".  If the baseline HVAC should be determined solely based on
the conditioned floor area and number of floors of residential versus
non-residential spaces, then why was the building type used as column
heading and in the note below the table? A case study in 90.1 User Manual
involves a building with 4 multifamily and 4 non-residential floors. The
4-storey 54,000 SF non-residential portion in the case study is modeled with
System 5, and the 4 residential floors are modeled with PTACs. If
corridors/stairwells in multifamily buildings are modeled with
non-residential baseline HVAC, then  most multifamily buildings over 5
floors would have System 7 serving these areas. I agree with Nathan that it
doesn't makes much sense, especially since most of these spaces are
indirectly conditioned by losses through interior walls of apartments. 

 

Maria

 

From: equest-users-bounces at lists.onebuilding.org
[mailto:equest-users-bounces at lists.onebuilding.org] On Behalf Of Nathan
Miller
Sent: Friday, August 17, 2012 11:32 AM
To: 'Ritwik Kakati'; equest-users at lists.onebuilding.org
Subject: Re: [Equest-users] LEED Baseline secondary HVAC system

 

Based on the exact wording of the Table G3.1.1A, I would say you are System
7, which is for "Nonresidential and more than 5 floors OR >150,000 SF.
However, we all can see that it is probably a pretty ridiculous baseline
system for a corridor ventilation unit.

 

On multifamily projects I've worked on, I've used system 5 in the past (even
though the floor number requirement would trigger system 7) and never been
called on it. That being said, usually that was on projects with ~7 stories,
so I was much closer to the threshold, so maybe the LEED reviewer just let
it slide. Even System 5 is a bit peculiar for a corridor unit. At least in
my climate they end up usually being packaged rooftop, constant volume
units. 

 

Nathan Miller, PE, LEED AP BD+C

Mechanical Engineer/Senior Energy Analyst

 

D 206-788-4577 | O 206-285-7100

 <http://www.rushingco.com/> www.rushingco.com

 

From: equest-users-bounces at lists.onebuilding.org
[mailto:equest-users-bounces at lists.onebuilding.org] On Behalf Of Ritwik
Kakati
Sent: Thursday, August 16, 2012 2:09 PM
To: equest-users at lists.onebuilding.org
Subject: [Equest-users] LEED Baseline secondary HVAC system

 

I am modeling a residential building under LEED 2009. With reference to
ASHRAE 90.1-2007, Exception 'a' in section G3.1.1 which states that we
should use additional system types for nonpredominant conditions if they
apply to more than 20,000 SF of conditioned space - I am confused which
system type I should use for my corridors and other non-residential
conditioned spaces, which are about  21,000 SF total, spread across 20
floors. Do I use System 7, because my non-residential spaces are located on
more than 5 floors, or use System 3 or 5 because the area is less than
25,000 SF?

 

Thanks,

 

Ritwik Kakati, LEED Green Associate

Design Engineer

DAGHER ENGINEERING, PLLC

29 Broadway, New York, NY 10006

T. 212.480.2591 x140

F. 212.480.2654

rkakati at dagherengineering.com

www.dagherengineering.com

 

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