[Bldg-sim] Existing building HVAC modeling

[Paul Riemer]

James,

Per part b of Seth's reference, his modeling solution only works if you do not cross the line between new and existing with any HVAC services (air, chilled water, hot water, dhw).   Once you do that, things get complicated.

Based on past experience, I highly suggest a through reading of Appendix G, existing CIRs and then writing your own to avoid being forced to remodel by the LEED review.

Paul



From: bldg-sim-bounces at lists.onebuilding.org [mailto:bldg-sim-bounces at lists.onebuilding.org] On Behalf Of Seth P. Spangler
Sent: Friday, September 04, 2009 8:23 AM
To: James Hansen; bldg-sim at lists.onebuilding.org
Subject: Re: [Bldg-sim] Existing building HVAC modeling

James,

If you are only adding an additional floor - and are not renovating any portion of the existing 1st-4th floors then I would model the 5th floor as if it was a new building by itself according to App. G guidelines. See Table G 3.1 item no. 2 in 90.1-2004


If the entire building is undergoing a renovation but the existing HVAC systems are existing to remain then the building would be modeled to reflect the existing system types and capacities. Refer to the LEED manual for these guidelines.

Hope this helps.

Seth Spangler, LEED(r) AP
Project Engineer

RMF Engineering, Inc
Ph: (843) 971-9639 ext:1497
Fax: (843) 971-9641
sspangle at rmf.com
From: bldg-sim-bounces at lists.onebuilding.org [mailto:bldg-sim-bounces at lists.onebuilding.org] On Behalf Of James Hansen
Sent: Friday, September 04, 2009 9:07 AM
To: bldg-sim at lists.onebuilding.org
Subject: [Bldg-sim] Existing building HVAC modeling

I'm modeling a building for LEED EAc1 compliance, and was wondering how you are supposed to model existing building HVAC systems if you are adding square footage to the building.

Let's assume you have a 4-story building with a 2-chiller HVAC plant and dual temp boxes.  If you were to add a 5th floor to the building, what would your baseline model look like?  I know that the 1st four floors would use the existing HVAC system, but would your new 5th floor be treated as a new 15,000 square foot area with packaged RTUs, or would you add a new chiller to the existing HVAC chilled water plant, and have that chiller meet all the requirements of App G, and have shutoff VAV boxes for the 5th floor in lieu of dual temp boxes?

For reference, under our proposed design, we are doing just that:  adding a frictionless chiller to the plant to make up the extra load.

GHT Limited
James Hansen, PE, LEED AP
Senior Associate
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