Reactive maintenance means fixing things after they break. Preventive maintenance means servicing them on a schedule so they break less often. Most buildings need some of both: preventive work for equipment where failure is costly or dangerous, and run-to-failure for cheap, easily replaced items. The goal is to choose deliberately rather than end up reacting to everything by default.
The main approaches
Reactive (run to failure)
Nothing is done until something fails, then it is repaired or replaced. It has the lowest upfront cost and needs little planning. The downside is unplanned downtime, emergency pricing, collateral damage, and failures at the worst possible times, such as a boiler on the coldest night of the year.
Preventive (time-based)
Tasks are done on a fixed schedule or after a set amount of use: changing filters every few months, lubricating bearings, cleaning coils, exercising valves. It reduces surprise failures and extends equipment life. Its weakness is that some work is done whether or not it is needed, and some failures are not related to age at all.
Predictive and condition-based
Equipment condition is measured, and work is done when the measurements show it is needed. Examples include infrared scanning of electrical equipment, vibration analysis of motors and pumps, oil analysis, and trend data from a building automation system. It targets work where it is needed, but requires tools, trained people and good data.
The idea behind condition-based work is that many failures give a warning first. Equipment condition starts to decline at a point where a problem becomes detectable, then falls away faster until it fails. The time between the two is the window in which planned work is possible.
Comparing them
| Approach | Best suited to | Main drawback |
|---|---|---|
| Reactive | Low-cost, non-critical items with no safety impact, such as some light fixtures or small exhaust fans | Unplanned downtime and higher cost per repair |
| Preventive | Equipment with known wear patterns and manufacturer schedules, such as HVAC, pumps and roofs | Some unnecessary work; misses random failures |
| Predictive | Critical, high-value equipment such as switchgear, large motors, chillers and generators | Needs instruments, expertise and data |
Why buildings drift into reactive mode
Most buildings do not choose to be reactive. They get there because preventive work is easy to postpone when budgets or staff are stretched, and each emergency uses up the time that should have gone into planned work. Over time the backlog grows and more of the budget goes to emergencies. Our guide to the real cost of deferred maintenance explains how this compounds.
Signs that a building is stuck in reactive mode:
- Most work orders are for breakdowns, not scheduled tasks.
- The same equipment fails repeatedly.
- Staff overtime and emergency contractor callouts are high.
- There is no reliable equipment list or maintenance history.
- Tenants report problems before staff know about them.
Shifting towards planned maintenance
- Know your equipment. Build an inventory with age, condition and service history.
- Rank by criticality. Ask what happens if each item fails: safety impact, cost, effect on tenants, and how long a repair would take. Critical items get preventive or predictive plans.
- Start small. Put the most critical equipment on a preventive schedule first, rather than trying to cover everything at once.
- Write the schedule. See building a maintenance schedule.
- Protect the time. Set aside staff time for planned work so emergencies do not consume it all.
- Measure. Track the share of planned versus unplanned work, repeat failures and response times, and adjust.
A worked example: choosing a strategy for each item
A typical case: a facility manager for a three-storey office building sorts the main equipment by asking the same questions of each item. What happens if it fails? Is anyone put at risk? How long would a repair take, and how much would it cost compared with maintaining it?
| Equipment | If it fails | Chosen approach |
|---|---|---|
| Main electrical switchgear | Building-wide outage, long lead time for parts, safety risk | Predictive: periodic infrared scanning plus preventive maintenance |
| Heating boiler | No heat in winter, possible frozen pipes | Preventive service before the season, plus the mandated inspection |
| Rooftop units | Comfort complaints in part of the building | Preventive: filters, belts and coils on the manufacturer's schedule |
| Washroom exhaust fans | Minor, quick and cheap to replace | Run to failure, with spares on hand |
| Interior light fixtures | One area dimmer until replaced | Run to failure |
Useful questions when ranking criticality:
- Could a failure injure someone or disable a life safety system?
- Would it stop the building or a tenant's operations, and for how long?
- Could it damage other systems, for example by flooding or freezing?
- How long are lead times for parts or replacement equipment?
- Is there a backup, such as a second pump or boiler?
- Does a warranty, insurer or regulation require documented maintenance?
The result is a deliberate mix. Staff time goes to the items where failure hurts most, and the cheap, non-critical items are simply replaced when they fail.
Using root cause analysis
When the same equipment keeps failing, replacing the failed part again only resets the clock. Ask why it failed, and keep asking until you reach a cause you can fix: a belt that wears out because the pulleys are misaligned, a pump that fails because it runs dry when a tank level control sticks, or a roof drain that blocks because nobody is assigned to clear it in the fall. Recording the cause on each work order, not just the repair, builds a history that shows which problems are worth solving for good.
Lean and continuous improvement methods fit well here: find the causes of repeat failures, fix them at the source, and standardize the work that prevents them.
Some maintenance is not optional. Life safety systems, elevators, boilers and pressure vessels, and other regulated equipment have required inspection and testing. Run-to-failure is never the right strategy for these.
How ehZee can help
ehZee's commercial building inspections document the condition of your building's systems, which is the starting point for deciding what belongs on a preventive plan. We can help rank equipment by criticality and set priorities for planned work.
Common questions
Is preventive maintenance always cheaper?
Not for every item. For low-cost, non-critical items, run-to-failure can be the sensible choice. For critical equipment, preventive and predictive maintenance usually cost less over the life of the asset.
What is a reasonable mix of planned and reactive work?
It depends on the building and its equipment. What matters is that the share of planned work is rising and that critical equipment is not failing unexpectedly.
Do we need special equipment for predictive maintenance?
Some methods, such as vibration analysis and infrared scanning, need instruments and trained people, and are often bought as a contracted service. Others are simpler: trending data your building automation system already collects, such as run hours, temperatures and alarms, can show equipment drifting before it fails.