The project team must use equipment life values from the 2007 ASHRAE Applications Handbook as listed in the LEED Reference Guide. For equipment not listed in the ASHRAE Applications Handbook, the equipment life must be assumed to be 15 years—no estimates are allowed. An alternative equipment life may only be used if a manufacturer’s guarantee and equivalent long-term service contract can be provided. 

Question
How can I document a longer equipment life (20 or 30 years) than what is listed in the LEED Reference Guide?
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