Glossary
RUL (Remaining Useful Life)
Plain-Language Definition
The estimated number of years a building component or system can continue to function adequately before requiring replacement, based on its current condition and expected deterioration rate.
Technical Context
RUL estimation considers: original expected life (ASHRAE provides reference lifespans for MEP equipment), current age, observed condition, maintenance history, and operating environment. Example reference lifespans: chillers 20-25 years, AHUs 15-20 years, lifts 20-30 years, flat roofing 15-20 years, switchboards 25-30 years. RUL drives CAPEX planning in property condition assessments (ASTM E2018). Actual RUL can deviate significantly from reference values based on maintenance quality.
Why It Matters
RUL directly impacts financial planning. Equipment near end-of-life requires imminent capital expenditure. During acquisition due diligence, RUL analysis determines whether the purchase price adequately accounts for upcoming replacement costs. A building with multiple major systems at end-of-life presents significantly higher near-term CAPEX requirements.
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