Rating System

LEED BD+C: New Construction

Rating System Version

v2 - LEED 2.2

Inquiry

The project team is seeking guidance on the preferred energy modeling approach for our project. The project has a central boiler plant that serves the entire existing building and will be upgraded to serve the addition and renovation that are included in this project. A separate cooling system is being installed that is completely isolated from the system serving the existing facility. One new air handling unit serves a renovated area, part of a new addition and an existing area that is not included in our project "LEED Boundary". Our request focuses on the approach to modeling this air handling unit. We intend to model the boiler plant as a district energy system per the document published by the USGBC, "Required Treatment of District Thermal Energy in LEED-NC Version 2.2 and LEED for Schools", following Steps 1 and 2 as appropriate. We intend to model the new cooling system as designed, as an independent system (i.e. not part of a DES) since it serves only areas within the "LEED Boundary". We intend to include all areas within the building that are served by the new equipment, including the spaces that are not affected by any other work, which are excluded from our project "LEED Boundary" in other credit calculations. Furthermore, we intend to exclude the existing portion of the building that is not being affected by the project work, which is also excluded from our "LEED Boundary". Per Appendix G, Table G3.1, Section 2 Additions and Alterations, "It is acceptable to predict performance using building models that exclude parts of the existing building (sic) provided that all of the following conditions are met: (a) Work to be performed in excluded parts of the building shall meet the requirements of Section 5 through 10. (b) Excluded parts of the building are served by HVAC systems that are entirely separate from those serving parts of the building that are included in the building model. (c) Design space temperature and HVAC system operating setpoints and schedules on either side of the boundary between included and excluded parts of the building are essentially the same. (d) If a declining block or similar utility rate is being used in the analysis and the excluded and included parts of the building are on the same utility meter, the rate shall reflect the utility block or rate for the building plus the addition (sic). It is the project team\'s understanding that each of these conditions will be met by the model as described below: (a) No work will be included in excluded parts of the building. (b) Excluded parts of the building are those served by separate HVAC systems. The area that is served by a common HVAC system that is being installed as part of the new work will be included. (c) Design space temperatures, operating setpoints and schedules are essentially the same, as the entire building is occupied by the same tenant. (d) The utility rate structure used in the analysis and the energy savings calculations will comply with this requirement. In summary: 1) Appendix G states that excluded parts of the building must be served by separate HVAC systems. 2) The LEED Rating System and each CIR that has been submitted follows a common theme of "Whatever is within the "LEED Boundary" must be accounted for within each credit. 3) We need the review team to determine whether it is necessary to change the "LEED Boundary" to include the areas served by the new AHU that are NOT being affected in any other way. If it is determined that it is not necessary to change our "LEED Boundary", we would like the review team to determine whether it is acceptable to model the building as designed within our "LEED Boundary" and also include the portion of the building served by the new AHU in order to be in compliance with Appendix G. This area would not be included in other "LEED Boundary" governed credit calculations.