Appendix G system type for addition

Within the LEED boundary.

Does this apply the same to a 90,000 sf addition to an existing hospital were we are using steam and chilled water from a central plant but all other systems are separated?  I see this similar to a campus set-up just that the buildings adjoin on two of the four floors.  The link below is to a LEED interpenetration stating that "The addition be modeled separately with its own plant that is appropriately sized in the budget and proposed design models. The efficiency of the plant equipment should match that which is installed at the existing building, unless new equipment is being installed to meet the load from the addition. If new plant equipment is being installed, it should meet the minimum requirements of ASHRAE 90.1-1999 Section 6. The name of the LEED registration should incorporate the term "addition" or similar descriptor, as it is only the addition that is being submitted for certification."   Does this apply?  Can the baseline systems be based on a 90,000 SF building?  Can I model the plant as described in the LEED interpretation?

https://www.usgbc.org/content/li-5496

Yes it does. The baseline systems should be for the addition only.

Wow you dug up an oldie. We actually submitted that CIR many moons ago. Technically it does not apply to 2009 projects since that rating system is not listed but the method is very similar to the method used in DESv2 Option 2 which you could apply to your situation. You could also apply DES v2 Option 1 or 90.1-2007 addendum ai. 

Thank you for the quick response!!

One other question - 90.1 requires that unfinished or shelled spaces are modeled with the baseline system design in both the baseline and proposed.  With the chilled water system in place for the proposed system would it make sense that the proposed could be closer to the design and not modeled as the baseline system?  In the past I have modeled shell space as heat only, but it does not appear that it was correct per 90.1.   

For a shell space without an HVAC design you would model the other system components identical to the Baseline system requirements. If it is an air-side system in the baseline simply change it to a water-side system like you would for DESv2 Option 2.

Does DESV2 apply to LEED V4?  I do not have the existing building modeled.  The existing plant is not metered to the point we can establish energy rates.  I do know the existing boiler and chiller efficiencies.  The old LEED interpretation allowed for the use of the CUP efficiencies on equipment sized for the new building.  DESV2 option 2 appears to require the existing plant to be modeled.  Is there an interpretation of DESV2 that does not require modeling the existing plant and in tern modeling the existing building?  

DESv2 applies to LEED 2009. The district energy guidance in LEED v4 is in the Reference Guide.

There are two methods for modeling the plant under Option 2 and one of them allows you to use default values. You would not have to model the existing building.

You could also follow DESv2 Option 1 or 90.1-2007 addendum dn and model the heat and cooling as purchased energy.

And for another similar problem: I have a building divided in two parts (warehouse and office). Office is served by district heating and cooling system and warehouse is served by a separate heat pump for heating and cooling. I submit the project as a district, but how can I model the heat pump (it is not in the district system)?

Apply the district approach to the office and straight Appendix G to the warehouse.