[Bldg-sim] Question: Table G3.1

[Kevin Kyte]

Vikram - Is there any way the district thermal methods prescribed by LEED could help?  - Don't know if it will help, just a suggestion.
Perhaps a prescriptive approach is best.

Kevin J. Kyte, PE, BEMP, LEED (r) AP
Mechanical Engineer
Watts Architecture & Engineering, P.C.
95 Perry Street, Suite 300
Buffalo, NY  14203
p:  716 206 5174
f.:  716 206 5199
e:   kkyte at watts-ae.com<mailto:kkyte at watts-ae.com>
http://www.watts-ae.com<http://www.watts-ae.com/>

From: Nick Caton [mailto:ncaton at smithboucher.com]
Sent: Monday, December 19, 2011 5:26 PM
To: Sami, Vikram; bldg-sim at lists.onebuilding.org
Cc: Glazer, Breeze
Subject: Re: [Bldg-sim] Question: Table G3.1

Hey Vik,

Sounds something like a rock and a hard place, but then I've never pursued LEED for only an addition.  It's my hope someone who has can chime in with a tested position/approach.  I'm unfamiliar with the CT standards but it seems worth nailing down whether they share the same interpretations as well.

I can offer a few scenarios/suggestions that may help work around the situation instead of through it in any case:


*         If your target is to achieve LEED certification for the addition only... I've seen auditorium and periphery spaces in large schools effectively conditioned with their own independent packaged systems... any chance that might be considered for the design?  If so that might conveniently avoid the issue entirely, by not tying into the existing boiler/chiller.  This assumes you won't have other issues meeting the conditions for Table G3.1, part #2.

*         I have had the fortune to be involved in a similar high school project which did not explicitly seek or require LEED certification, but the district and design team were collectively very energy conscious and pursued a unique approach without any such mandatory/enforced regulations.  Budgets were arranged from the beginning to encompass both a large new building addition in addition to targeted retrofits/replacements of existing HVAC, envelope and lighting systems.  The cohesive goal was to identify and implement the most cost-effective means to reduce and minimize the "whole building" EUI and utility bills - only rarely focusing on the new addition in isolation of the "big picture."  This was a very involved and satisfying process... and in the end I think everyone came away feeling the right decisions were made for the entire facility with the resources available.  With all that in mind - are you too far along to consider re-allocating (or expanding) your project budget, perhaps VE-ing portions of the present design, to put those dollars to more effective use retrofitting/improving existing systems?

Still for what it's worth, this specific interpretation does come across as very "by the book" and in practice unreasonably inflexible considering LEED certification is being sought only for the addition.  On the flip side, the interpretation request language is not nearly so clear as your more concise email just now - possibly the responder hasn't fully grasped why you're asking.  If the individual(s) providing this clarification are open to a discussion, I would propose extending the conversation to recognize "the whole building must be modeled" and "the whole building must be incorporated into the performance rating" as two importantly distinct statements - and that's the clarification you're driving towards.

It would seem reasonable for the proposed model of a building addition to incorporate and approximate the systems & building areas not involved in the addition (modeling the whole building effectively), separately meter all "existing to remain" loads and systems, and then calculate the proposed performance rating specifically using a weighted fraction of the energies consumed by shared & existing-to-remain systems (boilers and chillers, in this case).  All other consumptions exclusive to the addition could then be isolated and removed from the performance rating calculation.  Adopting a procedure along these lines would have a number of positive effects, including:

*         Leveling the playing field for additions to small vs. large buildings

*         Encourage designers to consider replacing, upgrading and/or improving the operations of existing shared systems to remain

*         Not driving design teams to construct entirely independent HVAC systems where it may make a lot more sense for the building owner/environment to utilize existing systems of sufficient capacity.


Maybe some of this will help you plot a course with the powers that be, though I sincerely hope there's a more definite answer/precedent to draw upon.

Best wishes,

~Nick

[cid:image001.jpg at 01CCBF39.B7226EF0]

NICK CATON, P.E.
SENIOR ENGINEER

Smith & Boucher Engineers
25501 west valley parkway, suite 200
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> [mailto:bldg-sim-bounces at lists.onebuilding.org] On Behalf Of Sami, Vikram
Sent: Monday, December 19, 2011 10:59 AM
To: bldg-sim at lists.onebuilding.org<mailto:bldg-sim at lists.onebuilding.org>
Cc: Glazer, Breeze
Subject: [Bldg-sim] Question: Table G3.1

Here's a brain puzzler for the list.

I'm assisting a team designing an addition (auditorium + rehearsal space) to an existing high school in Connecticut. As a public project receiving state funding, CT's High Performance Building Standard applies which requires a 21% energy cost savings (LEED for Schools Silver is also targeted for the new addition only).

The new space will have independent/new ventilation systems, but will most likely utilize the boiler and potentially chillers of the existing school building.

Buried in ASHRAE modeling guidelines, we discovered (long after project started and engineers "completed" the model) that  additions and alterations that share HVAC systems with existing spaces, are required to include those spaces in their energy model. The new space is designed for a 24% reduction - but if the existing spaces (approx. 3x the sf of new space) are included performance will fall way below the required threshold.

We can't understand how other  LEED projects in similar situations ever meet energy reduction requirements, has anyone dealt with this on a LEED project and found ways to circumvent? Has anyone come across a similar condition, and if so - how did you approach it?


Many Thanks in advance -

Vikram

Vikram Sami, LEED AP BD+C
Sustainable Design Analyst
1315 Peachtree St. NE, Atlanta, GA 30309
t: 404-443-7462    f: 404.892.5823       e: vikram.sami at perkinswill.com<mailto:vikram.sami at perkinswill.com>   www.perkinswill.com<http://www.perkinswill.com/>
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