If the building is newer than the rated life of the equipment in question, then the remaining life is equal to the difference of rated life and building age. If the building is older than the equipment's rated life, FEDS assumes that on average, equipment will be halfway through their life (but users can override this assumption and specify actual equipment vintage). Rated lives vary by equipment technology. Some examples of rated lives used in FEDS are:

• envelope components (windows, insulation, etc.) – 40 years
• lights – typically 25 years (Although the cost of replacing lamps and ballasts is figured into the analysis based on specific replacement intervals and hours of operation)
• boilers – 40 years
• furnaces – 20 years
• chillers – 20 years
• package AC units – 15 years
• heat pumps – Air Source/15 years, Ground-Coupled/20 years
• motors – 15 years
• hot water heaters – electric, 12 years; gas, 10 years; distributed heat pump, 12 years; central heat pump, 15 years