This question is in regards to the administrative alternative calculation method for this credit described in a credit ruling dated 01-11-2005. The method has since been rescinded but it can still be used by projects which were registered for LEED prior to October 15, 2005. The question is whether the calculation defaults published for LEED-NC v2.2 should be used or whether those mentioned in the ruling dated apply. For example, a 30 year life is mentioned as the default for equipment in the rescinded ruling, which is a bit of a stretch for small 5-ton HVAC units, but 10 years is used in LEED-NC v2.2 as a default unless documented otherwise. The difference in the default values is not trivial. The rescinded defaults can allow projects to use significantly more HVAC equipment of higher ozone depletion potential than would be allowed under LEED-NC v2.1 for non-HCFC equipment (assuming a maximum 15% non-base building exemption), or under LEED-NC v2.2 following its calculation requirements. For those projects which can still use the rescinded ruling can the USGBC please provide clarification on the defaults values to use, and what associated supporting documentation requirements should be provided for small sized equipment, if any. Also, a CIR ruling dated 11-04-2002 allows up to 15% of non-base building equipment to be excluded from the credit requirements. Does the alternative calculation method allow for the exclusion non-base building equipment up to 15% of total HVAC capacity, or must all equipment be included to show compliance?
In reference to the EAc4 CIR of 1-11-2005, the project wishes to know a) which default assumptions to use in the CIR\'s alternative calculation method, and b) whether any building systems can be excluded from that alternative calculation. Regarding the first question, if the project team is eligible to use the CIR\'s alternative calculation method (i.e., if it registered before the 10/5/05 and is pursuing LEED-NC v2.0 or v2.1 certification), then it may use the default assumptions listed in the 1-11-2005 CIR itself. Projects that registered after the cutoff date must use the methodology and default assumptions published in LEED-NC v2.2. Regarding the second question, the CIR\'s alternative calculation method is intended to include all refrigerant-containing building equipment. Consistent with LEED-NC v2.2, small HVAC units and other equipment - such as standard refrigerators and water coolers - containing less than 0.5 lbs of refrigerant are not considered part of the "base building" system and are not subject to the requirements of the CIR alternative calculation method, and need not be documented in the LEED submittal. Applicable Internationally.