The cheapest energy is the energy you never use — and scheduling is how a building automation system avoids conditioning empty space. Beyond simple on/off schedules, optimal start learns how long a building takes to reach comfort and starts the equipment just in time, while optimal stop coasts to the end of occupancy on stored thermal mass. Together they are among the simplest, highest-return control strategies a building can run.
The most basic and most valuable control strategy is simply not running equipment when the building is empty. An occupancy schedule turns systems off (or sets them back) during unoccupied hours — nights, weekends, holidays — and back on for occupancy. A building conditioned 24/7 that is only used 50 hours a week is wasting enormous energy.
It sounds obvious, yet overridden or disabled schedules are one of the most common faults found in real buildings — someone put a system in “on” to solve a complaint and never set it back.
During unoccupied hours, the building does not shut off entirely — it sets back. Temperatures are allowed to drift to wider limits (warmer in cooling season, cooler in heating) so equipment runs minimally, and in Florida, humidity is still held to prevent moisture problems in the empty building.
That Florida caveat matters: a building that fully shuts down overnight in summer can grow damp, so the setback strategy keeps dehumidification active even while relaxing temperature. The controls balance energy savings against moisture protection.
A fixed schedule has to start equipment early enough to reach comfort by occupancy on the worst day — which means on every other day it starts too early and wastes energy. Optimal start solves this: the controls learn how long the building actually takes to recover from setback under current conditions, and start only as early as needed to hit comfort right at occupancy.
On a mild morning it starts late; on an extreme one, earlier. The result is the building is comfortable exactly when people arrive, with no wasted pre-conditioning — an adaptive strategy that improves as it learns the building.
The mirror image: a building does not need active conditioning right up to the last minute of occupancy, because its thermal mass will coast. Optimal stop shuts equipment down before occupancy ends, letting the building drift within comfort limits for the final stretch on stored thermal energy.
Done carefully, occupants never notice, and the building saves the energy of running equipment during hours it did not strictly need it. Like optimal start, it adapts to conditions rather than using a fixed time.
Scheduling and optimal start/stop are pure software — no new equipment, just better control — so they cost almost nothing to implement on a capable system and save real energy immediately. They are usually the first thing a good controls retrofit or tune-up addresses.
They also depend on the schedules actually being correct and un-overridden, which is exactly the kind of drift that fault detection and retro-commissioning catch. Setting them up is easy; keeping them honest is the ongoing work.
Optimal start learns how long a building actually takes to reach comfort from a setback condition and starts the equipment only as early as needed to hit comfort right at occupancy. On mild days it starts late; on extreme days, earlier — avoiding the wasted pre-conditioning of a fixed early start time.
Optimal stop shuts HVAC equipment down before occupancy ends, letting the building coast within comfort limits on its stored thermal mass for the final stretch. Occupants do not notice, and the building saves the energy of running equipment during hours it did not strictly need.
A building that fully shuts down overnight in a humid climate can grow damp, so Florida setback strategies relax temperature limits to save energy while keeping dehumidification active to protect the empty building from moisture problems. The controls balance energy savings against humidity control.
Scheduling and optimal start/stop are pure software — no new equipment, just better control — so they cost almost nothing on a capable system and save energy immediately. They are usually the first thing a controls retrofit or tune-up addresses, though schedules must be kept correct and un-overridden to keep saving.
Suncoast Cold Systems installs, wires, and configures the HVAC controls integral to the mechanical systems we provide — and specifies open protocols (BACnet, Modbus, open supervisory platforms) so you own your building’s controls and data, with no proprietary dealer lock-in. Where a project calls for certified systems integration, we coordinate it within one accountable mechanical scope. Licensed Florida Class A Air Conditioning Contractor (FL #CAC1824642).