LED Lighting Retrofit with IoT Controls

Lighting is the most approachable energy project in most commercial buildings, and the one most frequently done incompletely. Replacing fluorescent tubes with LED is a solid first step - the efficiency gain is real and the payback is short. But a retrofit that stops at the lamp swap leaves half the savings on the table, because the larger opportunity is not in the light source. It is in the control: dimming a fixture 20 percent saves roughly 20 percent of its energy, and stopping a fixture from running in an empty room saves 100 percent of it. An IoT-enabled retrofit combines the efficient source with the intelligence to use it only when and where it is needed.

What the Retrofit Actually Changes

The lighting load in a typical commercial office runs 15-25 percent of total building energy, and much of it is wasted: offices lit overnight, corridors at full brightness at noon, and daylight-adjacent rows burning at the same level as the windowless interior. The retrofit addresses waste at three levels:

• The source. Modern LED fixtures deliver roughly 100-150 lumens per watt, compared with 60-80 for T8 fluorescent and 15-20 for legacy incandescent. Swapping sources alone typically cuts lighting energy by 40-50 percent with no change in behavior.
• The control. Dimming, scheduling, and daylight response cut the remaining load further - the combined effect is where the 60-70 percent totals come from.
• The intelligence. Connecting fixtures to occupancy, daylight, and schedule data turns lighting into a responsive system rather than a fixed install that ignores the space.

The Payback Math

A concrete example makes the case. Consider a 5,000 square meter office lit to 300-400 lux with 800 T8 fluorescent troffers, running 3,000 hours per year at about 55 watts per fixture including ballast losses - roughly 132,000 kWh per year for lighting.

• Replacing with LED troffers at 32 watts each cuts consumption to about 77,000 kWh - a 42 percent reduction worth roughly 55,000 kWh per year.
• At $0.12/kWh, that is about $6,600 per year saved from the source swap alone.
• Adding occupancy and daylight controls typically saves another 25-40 percent of the remaining load, pushing the total to 60-70 percent - roughly 90,000 kWh and $10,800 per year.

At a retrofit cost of $90-150 per fixture installed, payback lands between 3 and 5 years for the lamps alone, and better with controls.

The Controls That Deliver the Savings

Daylight Harvesting

Daylight harvesting dims fixtures in proportion to available daylight, keeping total light at target. A photosensor per zone or row measures horizontal illuminance and drives a dimming curve. In a perimeter zone with good glazing, savings typically run 20-40 percent during daylight hours - larger near the window, negligible in the core. The practical rules: calibrate the sensor against the target illuminance at the work plane rather than the ceiling, and set a floor (typically 30-40 percent) so spaces never feel abandoned.

Occupancy-Based Control

Occupancy control is the biggest and least controversial lever. Vacancy sensing - turning lights off when a room is empty rather than on when someone enters - saves without any occupant-visible downside. In open-plan offices, per-zone vacancy control using ceiling-mounted occupancy sensors routinely delivers 30-50 percent savings compared with schedule-only operation, because meeting rooms and break areas are the classic waste sites.

Scheduling and Demand Response

A schedule sets the baseline and control fills the gaps. An office that turns off at 7 p.m. and ramps back at 6 a.m., with vacancy override during the day, captures after-hours waste no sensor logic can match. Lighting is also a demand-response asset: at 15-25 percent of building load and dimmable, a 20 percent dim event during a utility peak shaves a meaningful chunk off a demand charge without displacing occupants.

Dimming Profiles and Lumen Maintenance

LED drivers accept a range of control signals - 0-10V, DALI, DMX, and increasingly wireless protocols. The strategy should include lumen maintenance: because LED output degrades slowly over life, a constant-light-output mode that raises power slightly as the lamp ages keeps illuminance stable while using less energy than a fixed high output. The key retrofit compatibility question is whether existing wiring supports the control protocol or whether wireless controls are needed to avoid new conduit.

Integrating with the Building Platform

The retrofit’s value multiplies when lighting joins the building’s data. Once fixtures are networked, they become occupancy sensors in their own right, and their energy data reconciles against the building’s power metering. The integrations that matter:

• Reconciliation with submetering - lighting energy should track lighting control events; unexplained divergence means a misconfigured zone or stuck override.
• Cross-checking with HVAC - if a space is lit and occupied, its HVAC zone should be active; when the two disagree, one system is wasting energy.
• Reporting per zone - per-floor and per-zone lighting energy turns the retrofit from a one-time saving into a continuously auditable number.

Commissioning: Where Retrofit Savings Are Made or Lost

A retrofit is only as good as its commissioning, and this is the step most frequently rushed. Proper commissioning covers:

• Sensor coverage - occupancy sensors must cover the zones they control, with no dead spots and no cross-zone false occupancy.
• Dimming calibration - daylight sensors calibrated against the target illuminance at the work plane, not the sensor’s own reading.
• Scene and schedule verification - every zone exercised in person, not just sampled.
• Override discipline - occupant overrides that default back to schedule rather than switching everything to “always on” and staying there.

Skipping commissioning typically costs 15-25 percent of the projected savings, because a misconfigured sensor that forces lights on in an empty zone eats exactly the savings the retrofit was bought to create.

Conclusion

The LED retrofit is the entry point to building efficiency, but its real payoff comes from treating it as a control project, not a lamp project. Source efficiency alone delivers roughly half the available savings; occupancy, daylight, and scheduling controls deliver the rest, and networked fixtures turn lighting into an occupancy and energy data source for the whole building. Teams that size fixtures for dimming, commission controls properly, and integrate the data with the rest of the facility get a project that keeps saving year after year instead of a one-time lamp swap.

Integrar IoT’s platform ingests lighting control and submetering data alongside HVAC and occupancy sensing, so a retrofit’s savings are verified, reported, and reconciled with the building’s other systems rather than assumed.