Understanding Beyond Useful Life

April 22, 2014

BOMA Beyond Useful Life sketch

In preparation for our upcoming webinar on April 29, “Tackling Beyond Useful Life,” we wanted to address the definition and real world meaning of “useful life.” Lawrence “Larry” Schoen, author of BOMA International’s Preventive Maintenance Guidebook: Best Practices to Maintain Efficient and Sustainable Buildings, provided us with some clarification of the term and its impact on decision-making. Check out Larry’s answers below and don’t forget to register for next week’s webinar!

Q: What is the real world interpretation of beyond useful life? What are some ways that it can vary?

A: Let’s make a distinction between theoretical useful life and practical useful life.  As Yogi Berra said, ”In theory, there is no difference between theory and practice; in practice, there is.”  BOMA International’s Preventive Maintenance Guidebook: Best Practices to Maintain Efficient and Sustainable Buildings contains pages of average useful lifespans for building systems and components.  These are averages and can be used for prediction, so I’d call them theoretical.  Practical useful life, however, may vary considerably, based on the robustness of the original installation, how well it matches the use of the building, how well it is maintained, the severity of service it has experienced, and other factors.  For instance, if the use of a space changes from office to medical clinic, the HVAC system may become obsolete long before its expected useful life.


Q: So how should useful life be used for decision-making?

A: Average useful life is a prediction tool for budgeting.  A budget itself, used properly, is also just a prediction tool.  It is a mistake to arbitrarily replace equipment when it reaches a particular age just as it is a mistake to spend to the budget.  Replacement and budgeting decisions should be evaluated based on current needs, conditions and opportunities.


Q: Are the “lifespans” of systems created today expected to be longer due to improvements in technology, efficiency, etc.?

A: The short answer is not longer, but in fact shorter; here are a few of the reasons.  Many types of equipment are built with lighter, more optimally designed components that may not have the same level of robustness as older equipment.  So much equipment comes with digital controls and we all know how quickly that becomes obsolete.  Efficiency standards change and as newer, more efficient equipment is available, it may make sense to change out equipment sooner.  The focus on replaceable hardware and increasing pressure on labor cost means that preventive maintenance may suffer. Refrigerants and other substances with environmental impacts are phased out and newer materials are favored.  Having said that, for some system components, for instance, a stone floor, we don’t expect the lifetime to change.

Lawrence 'Larry' Schoen, P.E.


About Larry Schoen, P.E. & Schoen Engineering, Inc.
Larry Schoen is president and principal engineer of Schoen Engineering, Inc. in Columbia, Maryland and he is also an ASHRAE fellow. Schoen helps building owners and managers assess the real condition of their mechanical & electrical equipment, achieve maximum lifespan, and know when to upgrade or replace. Schoen Engineering also produces engineered construction documents for facility upgrades and is licensed in multiple states for mechanical and electrical engineering.


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