[Bldg-sim] ASHRAE 62 question

Chris Jones cj at enersave.ca
Thu Aug 26 17:36:18 PDT 2010


This is an important discussion, at least it is 
timely for my needs both as a reviewer and 
submitter.  I am very interested in hearing from 
other LEED (and other energy program, HPNC, 
Manitoby Hydro, etc.), energy simulation reviewers.

And with all due respect, Gord, I do welcome your 
consideration and thoughts on this issue, it 
needs to be made clear by the CaGBC and USGBC as 
to what the intentions are as to the budget case 
outdoor air requirements and exactly who "the 
authority having juristiction" is?

The first question is about "the authority having 
jurisdiction" - as far as labs, health care 
facilities, etc.  The second question is about 
air system design and what constitutes proper 
design as far as the outdoor air calculation and 
the intended long term purposes of the facility.

So first, "the authority having jurisdiction":

This is an excellent question about ASHRAE 90.1; 
without and with Appedix G cases; LEED - USGBC 
and that Review Organization and "the authority 
having juristiction".  For example, from the 
Green Care For Health Guide, Version 2.2, 
Appendix G, Design Assumptions & Procedures for 
Modeling for the GGHC Energy Credits:

"Ventilation, air changes and air pressure 
relationships: Use specific ventilation rates, 
air changes, and pressure relationships, as 
required by authorities having jurisdiction. If 
the authorities having jurisdiction have no 
specific requirements, use the requirements from 
2006 AIA Guidelines for Design and Construction 
of Hospital and Health Care Facilities, or most recent version. "

Then forther on, in the same document, it states:
"Process Ventilation loads:  Special ventilation 
requirements in a health care facility are not 
unusual.  While Table OCC-1 quantifies the 
typical ventilation in a health care facility, 
some spaces may require higher ventilation 
rates.  The higher ventilation rates shall be 
simulated in both the Baseline and Proposed 
building simulation runs, making this an energy neutral feature. "

 From the health care prospective, ventilation is 
very specific and the "authority having 
jurisdiction" is basically the facility and their 
designers.  Therefore the calculation of outdoor 
air requirements would have to be accompanied by 
letters from that authority - whom ever it might 
be.  In my experience these letters typically are 
submitted with a fairly detailed air system 
balance calculation noting the standards the designer is following.

I agree with this intent and I believe that the 
requirements for heat recovery cover cases like 
this where, in reality, HVAC systems often have 
in excess of 70% outdoor air and greater than 
5000 cfm and therefore the budget case system has 
heat recovery as a requirement (at least in 
reading 90.1-2004).  For smaller systems, the 
budget case will perform significantly poorer 
than the proposed design that has heat recovery.

I believe that the outdoor air requirements 
should be based on the minimums suggested in 
ASHRAE 62 and other standards such as CSA-Z317, 
but each facility had to determine their outdoor 
air requirements and should not be penalized by 
artificially restricting the budget case how the 
reviewer interprets the requirements of 90.1, 
LEED, 62.1, CSA Z317, the ASHRAE Application 
Table, Table 7.6.3 Ventilation Requirements for 
Areas Affecting Patient Care In Hosptitals and Outpatient Facilities, etc.

For example, in the case of a University facility 
with a new medical medical education facility 
complete with medical labs, exam areas, etc.  The 
"Owner" deemed certain spaces, systems as medical 
facilities and mandated typical health care, 
higher, ventilation rates.  While not all the 
building falls into this category, a reviewer 
must accept the  design outdoor  air requirements 
as meeting the requirements of "the authority 
having jurisdiction" and allow the budget case to 
have the same outdoor air amounts.

I believe that labs any medical labs fall into 
this category.  A level 3  lab had very strict 
ventilation requirements and the budget case will 
necessarily have the same outdoor air 
requirements and will have any heat recovery, 
ventilation control as required by ASHRAE 90.1, 
and the other standards to which the facility is designed.

SECOND - what constitutes "correct design" in 
terms of the level of outdoor air delivered.

Example, two examples, one a large long term, 
expandable, flexible HVAC system on a university 
campus - as the building will have, at one time 
or another in the detailed life cycle analysis 
for the facility, labs, dense occupant lecture 
theatres, offices, perhaps dormitories.  At any 
rate, the designers have decided, in their wisdom 
and I mean that with due respect, that the system 
should simply be a 100% OA system with variable 
flow control for all current and intended space 
functions.  So, yes there will be offices with 
100% OA.  As this is a single fan system, any 
critical outdoor air calculation will result in a 
100% OA system.  It will have variable flow 
control, demand ventilation control in zones with 
variable occupancy - either CO2 or occupancy 
sensor.  It will have heat recovery.

In this case, the budget case will indeed be a 
100% OA system, with heat recovery as per 
90.1-2004 6.5.6 and exhaust air control as per 
6.5.7 (as appropriate).  I don't believe that the 
USGBC, its review arm, the CaGBC, etc. can 
mandate that the outdoor air has to be lower 
because the system has use a critical zone 
calculation that results in more than 20% above 
the sum of the space by space, uncorrected 
ventilation rates - or some other arbitrary percentage.

In the other case, the facility is a smaller, 
fixed use but mixed use facility with a small 
portion requiring a 100% OA system and the other 
small portion being office, storage, corridors, 
etc.  The pressure and filtration requirements, 
and other design requirements (regardless of what 
standards), initial cost, controllability and the 
other myriad of design goals, results in a 100% 
OA system.  It is less than 5000 cfm, and but 
more than 70% OA.  In this case I believe that 
the budget case will should have the same 100% OA 
system and the not have heat recovery, exhaust control as per 90.1-2004.

I am very interested in hearing from other LEED 
(and other energy programs, 90.1, GGHC, HPNC, 
Manitoby Hydro, etc.) energy simulation reviewers.

Note that I am quoting 90.1-2004, that is the 
latest I can access, the 2007 electronic version 
has the wonderful feature of rendering itself 
useless when you upgrade your computer, 
apparently I have to contact ASHRAE somehow to 
provide an unlocking key, now where did I jot down that password?



At 04:20 PM 26/08/2010, Paul Erickson wrote:
>Content-Language: en-US
>Content-Type: multipart/related;
> 
>boundary="_004_FB9D7CB5B64CFF44BB1EA8B3CF88D7AE0294833E8CAEIMBaeiengla_";
>         type="multipart/alternative"
>
>Vikram,
>
>Good question
a bit interesting to try and answer.
>
>First, your calculations are correct.
>
>Second, it is interesting that only “educational 
>science laboratories” are mentioned, somehow 
>suggesting that their use is different from corporate and institutional labs.
>
>Third, EH&S often makes this determination and 
>there is no agreement among standards/guidelines 
>dealing with lab ventilation so to impose this 
>bit of Std 62 seems like something that the 
>USGBC should be considering as it moves towards 
>connecting Appendix G to Std 62 rates.
>
>Fourth, related to that last point, while 
>Appendix G does not yet directly require Std 62 
>rates for the baseline, LEED requires Std 62 
>rates for the proposed and 90.1 requires the 
>baseline ventilation to match the proposed.  So, 
>it would seem that models should be reflecting the 1 cfm/sf requirement.
>
>There is a grey area that I think may also be a 
>point of discussion.  Minimum exhaust rates of 
>various types are often only required when the 
>space is occupied.  As such, and considering 
>that many university EH&S folks are at least 
>beginning to bat around the notion of, if not 
>adopt, a 4 ACH minimum during unoccupied 
>periods, it seems fair to have a value lower 
>than 1 cfm/sf during unoccupied periods.  What’s your perspective on this?
>
>It’d be good if others chime in and help develop a consensus.
>
>Paul
>
>
>Paul Erickson  LEED® AP
>SR. Sustainable Design COnsultant
>
>AEI | AFFILIATED ENGINEERS, INC.
>5802 Research Park Blvd. | Madison, WI  53719
>
>P: 608.236.1112 | F: 608.238.2614
><mailto:perickson at aeieng.com>perickson at aeieng.com  |  www.aeieng.com
>
>
>From: bldg-sim-bounces at lists.onebuilding.org 
>[mailto:bldg-sim-bounces at lists.onebuilding.org] On Behalf Of Sami, Vikram
>Sent: Tuesday, August 24, 2010 10:49 AM
>To: bldg-sim at lists.onebuilding.org
>Subject: [Bldg-sim] ASHRAE 62 question
>
>Just going through table 6.4 in ASHRAE 62.1-2007 
>it looks like the minimum exhaust rates for labs 
>(educational science laboratories) is 1 cfm/ft2. 
>That amounts to an ACH of 6 (for a 10ft ceiling) and 6.7 for a 9ft ceiling.
>
>Am I interpreting that correctly? Does that mean 
>for LEED projects we cannot go below 6 – 7 ACH? Is there a way around it?
>
>
>Vikram Sami, LEED AP
>Sustainable Design Analyst
>1382 Peachtree St. NE, Atlanta, GA 30309
>t: 404-443-7462    f: 404.892.5823       e: 
><mailto:vikram.sami at perkinswill.com>vikram.sami at perkinswill.com 
>www.perkinswill.com
>Perkins+Will.  Ideas + buildings that honor the broader goals of society
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Chris Jones
14 Oneida Avenue
Toronto, ON M5J 2E3.
Tel.  416-203-7465
Fax. 416-946-1005

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