[Bldg-sim] Baseline Modeling for LEED

Tim Reynolds tim.reynolds at cbengineers.com
Fri Nov 20 09:12:50 PST 2009


Luka,

I agree with your sense of disappointment.  Although I'm not convinced
62.1 provides sufficient OSA for ventilation in some cases and provides
over ventilation at times, the intent of 90.1 is to reduce energy
consumption.  Even though I generally prefer to provide more than the
minimum OSA mandated in 62.1, the intent of LEED is to promote reducing
energy consumption in buildings.  Providing OSA rates greater than the
rates directed in 62.1 typically requires spending a bit more time with
design in order to minimize the impact of the additional ventilation
air.  It is reasonable to assume that LEED should recognize buildings
provided with more than the minimum OSA required to meet 62.1 should
either require creative means to minimize the energy impact of
additional ventilation or be penalized for increasing the ventilation
rate.

Tim

 

 

TIM REYNOLDS, P.E., LEED AP

Associate Principal

 

 

 

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From: bldg-sim-bounces at lists.onebuilding.org
[mailto:bldg-sim-bounces at lists.onebuilding.org] On Behalf Of
Matutinovic, Luka
Sent: Friday, November 20, 2009 5:47 AM
To: David S Eldridge; bldg-sim at lists.onebuilding.org
Subject: Re: [Bldg-sim] Baseline Modeling for LEED

 

This is a case of where LEED, IMHO, should supersede 90.1.  I'm very
surprised, and quite frankly disappointed, about Nathan's comments that
the USGBC has accepted 30% over-ventilation in the baseline building.
The intent of LEED, among other things, is to promote low-energy
building design.  If a designer chooses to over-ventilate a building by
30% over what is required by ASHRAE in order to achieve better indoor
air quality, the occupants are better off, the environment is not.  

 

The bottom-line is that the baseline building "could" have been
ventilated at ASHRAE rates, and the proposed design should be penalized
for not complying with accepted practice.  It's no different than if the
proposed chiller had a lower COP compared to 90.1 baseline. 90.1 and
ASHRAE define currently accepted practice and the proposed design should
be judged against the standard, not against itself.  It's just that in
this case there is a side-benefit of using more energy and 90.1
stipulates using the same ventilation rates, which muddies the issue.

 

I think the example of the hospital is a red herring, since hospitals
would not be designed to ASHRAE 90.1, rather more stringent ventilation
codes which would be applied to both the reference and proposed
buildings.  The result is compliance-neutral.  Choosing to ventilate
beyond governing standards, should be considered bad design practice in
terms of energy, even though it's considered good design practice for
other reasons. We can't have our cake and eat it too!

 

My CDN$0.02

 

Luka Matutinovic, B.A.Sc., LEED(r) AP

Green Building Consultant
 
T. 416.644.0649

F. 416.487.9766  
Toll Free 1.888.425.7255
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HALSALL ASSOCIATES LTD. 
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2009 Globe and Mail
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From: bldg-sim-bounces at lists.onebuilding.org
[mailto:bldg-sim-bounces at lists.onebuilding.org] On Behalf Of David S
Eldridge
Sent: Thursday, November 19, 2009 6:31 PM
To: bldg-sim at lists.onebuilding.org
Subject: Re: [Bldg-sim] Baseline Modeling for LEED

 

Quick answer:

 

90.1 does not care if you are pursuing EQC2, use the same OA quantities
in baseline and proposed for EAC1.

 

 

Long answer:

 

These are separate credits - the modeling takes place based on the
proposed design in comparison to a baseline that is only restricted by
90.1.  The OA requirement should be the same in both models subject to
any DCV or exceptional calcs or technologies.  This is not affected by
other LEED credits.  

 

The credit for increased ventilation takes place "before" modeling
starts.  This is besides the many cases for laboratories or hospitals
where the local code ventilation requirements are much greater than
ASHRAE 62.1 already - the proposed design is in effect already taking
the EAC1 penalty but earning the credit for increased ventilation under
the best practice design.  You wouldn't relax the baseline ventilation
to less than 30% in these cases!

 

I'm sure there are some proposed buildings out there that condition OA
very effectively, and may gain EAC1 gross energy cost savings by having
increased ventilation, but even where that effect occurs there is  the
question of percentage savings applying to a larger energy consumption
and cost.

 

Overall if you gain EAC1 points by pursuing increased ventilation, I
think you have worked well within the system - good for you in designing
a system to condition outside air so effectively.  For many projects
(other than labs or hospitals which may have to use that quantity of OA
anyway) I would expect EQC2 could be trading for an EAC1 credit, so
you'll have to prioritize.  Both are rewarded from USGBC, but EAC1 is
also rewarded in lower utility bills.

 

David

http://www.grummanbutkus.com

 

 

 

From: bldg-sim-bounces at lists.onebuilding.org
[mailto:bldg-sim-bounces at lists.onebuilding.org] On Behalf Of Vikram Sami
Sent: Thursday, November 19, 2009 4:20 PM
To: Nathan Miller; Rimes, Christie; Steven Rutter;
bldg-sim at lists.onebuilding.org
Subject: Re: [Bldg-sim] Baseline Modeling for LEED

 

I always assumed that if you went to 30% extra, you kept the baseline at
100%, and the designed building at 130%, but after reading this, it does
seem to make sense that you would increase both occurrences. 

 

Can anyone from the EA Tag chime in?

 

Vikram Sami, LEED AP 
Direct Phone 404-253-1466 | Direct Fax 404-253-1366 

LORD, AECK & SARGENT ARCHITECTURE

 

From: bldg-sim-bounces at lists.onebuilding.org
[mailto:bldg-sim-bounces at lists.onebuilding.org] On Behalf Of Nathan
Miller
Sent: Thursday, November 19, 2009 4:42 PM
To: 'Rimes, Christie'; 'Steven Rutter'; bldg-sim at lists.onebuilding.org
Subject: Re: [Bldg-sim] Baseline Modeling for LEED

 

I disagree, I believe the models should be same-same on ventilation
rates. See section 90.1 (2004) Section G3.1.2.5. It states:

 

"Minimum outdoor air ventilation rates should be the same for the
proposed and baseline building designs."

 

In my projects (including those that include 30% additional outside
air), I have always used the same outdoor air flow rates, unless I was
taking credit for demand control ventilation in the proposed case (see
the exception allowed in that same ASHRAE section). 

 

Nathan Miller

Senior Energy Engineer/Mechanical Engineer

direct: 206.788.4577

fax: 206.285.7111 

 

From: bldg-sim-bounces at lists.onebuilding.org
[mailto:bldg-sim-bounces at lists.onebuilding.org] On Behalf Of Rimes,
Christie
Sent: Thursday, November 19, 2009 1:32 PM
To: Steven Rutter; bldg-sim at lists.onebuilding.org
Subject: Re: [Bldg-sim] Baseline Modeling for LEED

 

In  my experience you do not increase the baseline energy model as you
are being awarded (gaining that point) when you achieve the ventilation
credit. There are a few similar situations in LEED where by achieving
one credit will prevent you from achieving another but this happens to
everyone so it works out to be somewhat fair. 

 

 

 

From: bldg-sim-bounces at lists.onebuilding.org
[mailto:bldg-sim-bounces at lists.onebuilding.org] On Behalf Of Steven
Rutter
Sent: Thursday, November 19, 2009 1:25 PM
To: bldg-sim at lists.onebuilding.org
Subject: [Bldg-sim] Baseline Modeling for LEED

 

All,

There is a credit in LEED (EQc2.0) that involves increasing the required
ventilation rate by 30%.  In trying to achieve this credit, the amount
of energy would have to increase to condition that additional 30% OSA.
Does anyone know if you are supposed to increase the baseline energy
model's ventilation rate so it has the same ventilation rate as the
proposed building?  Thank you in advance for your help.

 

 

Steven Rutter, LEED(r) AP, EIT

 

 
3850 Happy Lane|Sacramento, CA 95827
O:916-368-0336|F:916-368-0337|C:916-717-7484

P Please consider the environment before printing this email. 

 

 

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