[Bldg-sim] ventilation only & LEED

christian stalberg cstalberg at naturalintelligence.us
Fri Jun 3 03:28:36 PDT 2011

After almost seven weeks wait, we finally received a response from USGBC. I 
post it below for the benefit of all:

Thank you for your technical customer service inquiry regarding LEED-NCv2.2. 
Thank you for your technical customer service inquiry regarding LEED-NCv2.2. 
Yes, as unconditioned space, these enclosures may be modeled without heating 
or cooling.  The inquiry further explains that energy savings are being 
taken for these ventilated only areas based on the proposed high efficiency 
fans and louvers provided. Note that in the unconditioned space, the 
ventilation fans should be modeled identically in the Baseline and the 
Proposed case, as process energy use.  In the Baseline case, the fans may be 
modeled with the minimum motor efficiency as required by ASHRAE 90.1-2004, 
Table 10.8, and they should be modeled in the Proposed case with the motor 
efficiency as designed.  Also, note that the fan schedules should be modeled 
identically in the Baseline and Proposed case.   If the fans as designed are 
controlled by air temperature; the Baseline fans should be modeled to 
operate in the same manner.

If any further savings are anticipated by additional energy efficiency 
measures for the ventilation fans, these should be modeled using the 
Exceptional Calculation Methodology. A narrative should describe all 
Baseline and Proposed case assumptions included for this measure, and the 
calculation methodology used to determine the projected savings. The 
narrative and energy savings should be reported separately from the other 
efficiency measures in the template, Section 1.7. The Baseline case 
description should verify that the efficiency measure is not standard 
practice for a similar newly constructed facility by referencing a recently 
published document, utility incentive program that incentivises the 
equipment installed, or by documenting systems used to perform the same 
function in other newly constructed facilities. Savings associated with the 
Proposed case measure should also be justified with published or monitored 

----- Original Message ----- 
From: "Jason Glazer" <jglazer at gard.com>
To: <bldg-sim at lists.onebuilding.org>
Sent: Wednesday, June 01, 2011 12:30 PM
Subject: Re: [Bldg-sim] ventilation only & LEED

Please note that 90.1-2010 has new baseline HVAC system
types for heated only storage which are heating and
ventilation units. It also contains an allowance for fan
power related to non-mechanical cooling fans.


On 6/1/2011 11:22 AM, Jorge Torres-Coto wrote:
> Christian,
> For good or bad, I have ended up modeling many Warehouse
> Distribution Centers, which in essence have a very small
> front office and a very large warehouse that is only
> ventilated (by code). I have had to argue with LEED
> reviewers this point, fortunately successfully. The
> warehouse area is by definition "unconditioned space", just
> like Nick states. Though you still have to model an HVAC
> system per ASHRAE, but spreading the setpoints basically to
> outside air design conditions. The reviews I have had have
> made it through this way. By doing this with the setpoints,
> you will not have any unmet hours. But you are still
> providing the right amount of ventilation air per 62.1 and
> the right power for all the fans. The office is a totally
> different story, which you pretty much know the answer to.
> I have had the comments go both way on the following. Since
> the Warehouse is not conditioned I had one reviewer tell me
> to change the Baseline HVAC system to packaged units due to
> the fact that the only conditioned space was a tiny 10,000
> sq.ft. space. Other reveiwers have left me keep my standard
> ASHRAE System 8 baseline with the modifications mentioned
> above for the warehouse area. (I usually utilize two air
> handlers: one for warehouse and one for offices).
> Jorge E. Torres Coto
> 4830 Viewridge Ave.
> San Diego, CA 92123
> p 858.751.0933
> f 858.751.0937
> c 858.688.6088
> ------------------------------------------------------------
> *From:*bldg-sim-bounces at lists.onebuilding.org
> [mailto:bldg-sim-bounces at lists.onebuilding.org] *On Behalf
> Of *Nick Caton
> *Sent:* Wednesday, June 01, 2011 7:34 AM
> *To:* christian stalberg; bldg-sim at lists.onebuilding.org
> *Subject:* Re: [Bldg-sim] ventilation only & LEED
> 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
> cid:489575314 at 22072009-0ABB**
> **
> *NICK CATON, E.I.T.***
> Smith & Boucher Engineers
> 25501 west valley parkway
> olatheks 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 []
> 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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