[Bldg-sim] ventilation only & LEED

[Nick Caton]

Hi Christian,

 

A LEED reviewer brought up this issue for a heated/ventilated-only
garage space recently.  Owner did not want a cooling system beyond
ventilation, and one was not designed.  Ultimately, our reviewer cited
TG3.1.1.b / G3.1.10 directly, and I conceded to model baseline-esque
cooling systems in both models.  

 

I'm not sure section 2.2 is a great defense as it states the standard
doesn't apply to *envelopes* without a heating/cooling system... not
ventilation systems (2.2.b.).  A better defense is if your warehouse is
by 90.1 glossary terms an unconditioned space, by virtue of not meeting
any of the three conditioned space definitions.  In that case, I think
you could flatly reject TG3.1.1.b as "not applicable" if it were brought
up.  In our garage space above, this wasn't an option as it was
definitely a heated space (see glossary for underlined terms).

 

I'd agree modeling both models with ventilation only is the intuitive
thing to do in the context of a validation (LEED) model.  The intent of
this language however, if I'm not mistaken, is to discourage/punish
design decisions to omit heating and/or cooling systems entirely to save
energy.  Never mind that's actually a very effective strategy, under the
right circumstances and in moderation...  I've got some contrarian
opinions in this department, so I'll keep my mouth shut =).

 

~Nick

 

 

NICK CATON, E.I.T.

PROJECT ENGINEER

Smith & Boucher Engineers

25501 west valley parkway

olathe ks 66061

direct 913 344.0036

fax 913 345.0617

www.smithboucher.com 

 

From: bldg-sim-bounces at lists.onebuilding.org
[mailto:bldg-sim-bounces at lists.onebuilding.org] On Behalf Of christian
stalberg
Sent: Wednesday, June 01, 2011 5:32 AM
To: bldg-sim at lists.onebuilding.org
Subject: [Bldg-sim] ventilation only & LEED

 

The warehouse section of our facility in El Salvador is to be ventilated
only.  The textile section of the same building will be cooled and
humidity will be controlled. Other areas such as offices and cafeteria
will be cooled. There is no heating load in El Salvador. I reviewed
inquiry 5088 (copy below) which would suggest the warehouse should be
modeled with air conditioning in both the base case and the proposed
case even though no cooling will be provided.  Our building is a little
different than the building in inquiry 5088 in that it has no heating
load.  Therefore by the 90.1 standard, the standard does not apply
(section 2.2) and it is an unconditioned space.  We feel the ventilated
section of our building should be rated based on energy savings of
standard ventilation equipment versus the proposed high efficiency fans
and louvers that we are providing for ventilation.  We would like to
proceed with the ventilated enclosures being included in the model
without heating or cooling.  Please advise.

 

 

Inquiry Number: 

5088 

MPR/Prerequisite/Credit: 

EAc1: Optimize Energy Performance 

Posting date: 

11/27/2007 

 

   

It is not acceptable to allow spaces to exceed the unmet load hour
requirements of the ASHRAE 90.1-2004 Appendix G methodology. This is a
similar situation to naturally ventilated spaces, which are required to
include cooling systems to meet space loads in the proposed case even if
the actual building will contain no cooling. Building owners may always
choose to turn off HVAC systems, or not have them installed at all to
conserve energy, but the ASHRAE modeling protocol assumes that cooling
systems will be installed and run with sufficient capacity to meet space
loads. The applicant may use a set-point of 80 degrees Fahrenheit for
the maintenance bays, but cooling system capacity must be increased
until the requirements of ASHRAE 90.1-2004 section G3.1.2.2 are met. The
project may still receive credit for using an efficient cooling system
as compared to the ASHRAE baseline cooling system.

 

    Inquiry [ <https://www.usgbc.org/images/LI/Minus.GIF> ] 

 

Our project is located in Las Vegas and consists of a combination of
office spaces and maintenance bays for earth-moving equipment. The owner
is a large agency that sells, rents and repairs such equipment; these
repairs are done both inside and outside the building envelope. The
maintenance bays are occupied by mechanics and will be conditioned with
evaporative coolers and gas furnace heat, the system supplies 100%
outside air. This cooling system provides conditioning of the spaces but
is not able to meet all peak loads for a climate such as Las Vegas even
when these spaces are modeled with higher setpoint at 80 degrees. In
reality, if the maintenance bays go above the temperature setpoints, the
mechanics will continue work in the warmer conditions or take a break.
This is not difficult for maintenance bays, where some of the work will
also done outdoors with no conditioning at all. The owner does not want
to fully condition the maintenance bays with the intention of achieving
high levels of energy efficiency. We propose the following modeling
approach for EA Credit 1. -Baseline model will have a mechanical system
based on Table G3.1.1A of Appendix G with 80 degree temperature setpoint
for the maintenance bays. -Proposed Design model will have the system as
designed in the building that provides partial conditioning with the
same 80 degree temperature setpoint. We will not model additional
compressor cooling for hours where the system is not able to meet loads.
This approach will result in exceeding the difference in the unmet load
hours beyond 50 as required by Appendix G. However, this is a conscious
decision by the owner who wants to maximize energy efficiency by
providing limited conditioning through evaporative cooling for the
maintenance bays, and allow the temperatures to float higher during peak
conditions. We feel that this approach appropriately captures the intent
of the design, and gives credit to the energy efficiency measures being
taken. It also provides a way for demonstrating the value of an energy
efficient approach to the community in Las Vegas where compressor
cooling is increasingly used, often indiscriminately; this is a desert
climate and a different approach to comfort and conditioning is
possible. Is this approach acceptable? If not, can you advise us on an
alternative approach that addresses the desire of the owner to
demonstrate high levels of energy efficiency for using such a system?

 

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