I am working on a large (250,000 square-foot) addition to a 250,000 square-foot building, both are mixed-use but primarily hospital. We are simulating the addition as a separate building, although it shares a central plant with the original structure.
In this project, high-efficiency chillers and boilers are being added to the plant with sufficient capacity to meet the needs of the entire 500,000 square feet, plus 100 percent redundancy (owner's requirement) due to some extremely critical process equipment within.
My question is this: For the baseline case, I let the simulation software size the chilled water and hot water plants. For the proposed case, I don't want to simulate a plant that is 4X what is needed for the load (plus the normal engineering safety factor). Is it OK to simulate the proposed case with a reasonably-sized hot water and chilled water plant instead? Or is it necessary to keep the addition's HVAC systems coupled to the existing building? Note: I searced the CIRs for LEED 2009, and it appears that #10025 on 5/9/2011 permits the stand-alone simulation for the addition...
Thanks!
David Weigel, PE
Managing MemberThe Watt Doctors, LLC
16 thumbs up
February 8, 2012 - 10:08 pm
Following up on my own post, I also have seen denials of additions being treated as stand-alone when sharing chilled or heating water with existing building (CIR 2049, 3/4/2008 initially addressed this, but is not applicable to LEED 2009 or so it says). The CIR I noted above says heating water can be shared, I think... Am I correct, or no?
Marcus Sheffer
LEED Fellow7group / Energy Opportunities
LEEDuser Expert
5906 thumbs up
February 14, 2012 - 9:58 am
Look to the District Energy Systems (DES) guidance document for answers. You basically model a virtual plant in your proposed model sized to your addition.