As stated in CIR ruling dated 8/29/2003, "Mechanical (mainly HVAC ductwork and equipment) and electrical system components (smaller infrastructure-type items such as wires, cables, junction boxes) are to be excluded from the LEED calculations. If a project team chooses to include additional items as part of the base material cost, such as elevators, appliances, hot tubs, or other semi-mechanical/electrical components, it should do so for all relevant material credits, which include MR Credits 3, 4, 5 and 6." Does this exclusion include thermal insulation for mechanical and plumbing systems, or is mechanical and plumbing insulation considered a "semi-mechanical component"? Furthermore, does this exclusion apply to self-insulated HVAC ducts, including fiber glass duct board ducts and flexible insulated ducts? Recycled content is currently available for these materials and excluding them would not provide incentive to manufacturers for increasing their use of recycled content, or motivate projects to incorporate recycled-content insulations. These products are lightweight and of low relative cost, and would not unduly affect other recycled content decisions.
Note that the referenced CIR is from NCv2.1, and your CIR was submitted for v2.2. Version 2.2 credit requirements state that mechanical, electrical and plumbing components shall not be included. The Reference Guide provides additional detail, although it does not clearly address your question. The phrase "Mechanical, electrical and plumbing components" refers to all items specified within CSI MasterFormat 1995 Divisions 15 and 16. Aside from the rationale stated in the Reference Guide (re: high-priced assemblies/equipment that would skew calculations), it is hoped that in general this approach provides a fairly level playing field between LEED projects and avoids a project\'s inquiries about recycled content in products for which data is difficult or impossible to gather, and where recycled content is not generally going to be influenced by LEED. Admittedly, this is a broad-brush solution that may miss some incentive opportunities, but the scope of materials for this and similar MR credits requires consideration of both technical and administrative issues for LEED. These credits were originally designed around Divisions 2 through 10: products considered the most practical to influence, the most practical upon which to create credit calculations, and which represent the bulk of a building\'s mass. Applicable Internationally.