This inquiry concerns proposed Exceptional Calculation Measures (ECMs) we wish to use in the calculation of building energy consumption for EA Cr1. We plan to submit each of these ECMs as explained in the LEED-NC V2.1 Reference Guide on pages 145 to 148. ECM #1 - Low Pressure Drop Fan Systems ASHRAE 90.1 Section 11.4.3.i requires that fan system efficiency (BHP per CFM of supply air) shall be the same in the base case and the proposed design. Furthermore it limits fan power in the proposed case to be no more than the prescriptive limits set forth in Section 6.3.3. Because our building is a laboratory, with high pressure drop duct systems due to filtration requirements and heat recovery devices, we understand that we can adjust the base case as per the exception outlined in section 6.3.3.1 of ASHRAE 90.1. Our ECM proposes that we account for a reduced system static pressure in our design case, based on designing the systems for lower pressure drops than typical design practice. Designing air systems for lowered face velocity at coils and filter banks is a well recognized strategy for reducing fan energy. We would like to take credit for this strategy in our LEED submission. We propose that the base case fan power/1000 CFM be based on the Pressure Credit Formula of ASHRAE 90.1 Section 6.3.3, using "standard" face velocities for filters and coils as follows: Coils: 500 FPM at peak flow Filters: 500 FPM at peak flow HEPA Filters: 250 FPM at peak flow Our design case will be based on the actual face velocities, pressure drops, and fan hp specified in our design. Is this approach acceptable? ECM# 2 - Central Plant Efficiencies ASHRAE 90.1 Section 11.2.3 says that annual costs shall be determined using rates for purchased energy. The LEED-NC V2.1 Reference Guide clarifies (p 143) that the modeler needs to use the same rates for both the budget and proposed energy design. Our building is attached to the campus central utility plant(CUP), which supplies chilled water, steam and electricity. Our building does not purchase any of these utilities; rather the CUP purchases natural gas, which it uses to generate the other utilities. The campus also purchases some electricity from the local utility, which is then distributed via the CUP. Our situation differs from the situation of a building buying steam or chilled water from a central utility in three important ways: 1. Both the building and the CUP are owned by the same entity. 2. No utilities are purchased by the building; the point of purchase is at the CUP. 3. Our project has the opportunity to influence the design and operations of the CUP. LEED EA Prerequisite 3 requires that CUP equipment serving a building seeking LEED be CFC free (LEED-NC Version 2.1 Reference Guide, p131). To meet this requirement, the owner has agreed to upgrade the CUP to eliminate CFCs. It seems logical that if we must upgrade the plant to meet one LEED Credit we should be able to take advantages of the improved energy efficiency of the same plant to meet another credit. We therefore propose the following ECM: We will calculate chilled water, steam and electricity consumption for both the base case and design case buildings using the standard LEED EMP. We will then run a second model, which converts these consumption rates to utility costs as follows: Base Case - an ASHRAE 90.1 compliant gas/electric heating cooling plant, with gas and electricity purchased from the local utilities at current billing rates. Design Case - an appropriate fraction of the actual CUP, with gas purchased from the local utilities at current billing rates. Central utility plants with cogeneration are a well recognized energy saving strategy. We are asking to include the effects of the CUP in our overall energy model, to reflect the real energy consumption of the building. Is this approach acceptable?