74F is a useful zone target, but fixed commissioning settings rarely stay right. Contractors size them for worst-case summer load, BMS systems preserve them as constants, and actual conditions keep changing with seasons, renovations, and tenant moves.
What Setpoints Control
Commercial HVAC systems commonly use three setpoint layers. Zone temperature setpoints define each conditioned space's target. Supply air temperature setpoints tell the AHU how warm or cool incoming air must be to meet that target. Chilled water supply temperature setpoints determine the plant effort needed to produce that air condition.
Each layer affects the next. A 74F zone target needs supply air cold enough for peak conditions, though peak load is uncommon. Supplying 55F air when 58F would work on a mild day makes the chiller work harder than needed. That excess appears in kW demand.
Why Fixed Schedules Fall Short
BMS schedules are good at separating occupied and unoccupied hours. That worked for one tenant with one timetable. Multi-tenant buildings differ by floor, zone, and day of week, so a shared schedule misses those variations.
Because Zone 4, Floor 6 and Zone 7, Floor 3 use one AHU, a BMS schedule may treat them alike. Yet Zone 4 could be a busy open-plan area while Zone 7 is a conference room used two hours per day. Matching their supply air wastes conditioning in the empty room and can underserve the occupied one at peak load.
A schedule also ignores weather. On a 62F March day, an August chilled water setting has little purpose. Producing 44F water for a building that could run on 52F or 54F supply creates an 8-10 degree gap, adding compressor work, kW use, and demand-charge exposure.
Continuous Setpoint Change
Autonomous setpoint control maintains a live model of building thermal conditions. It considers zone temperatures, recent occupancy, outdoor temperature and humidity, time of day, and each zone's historical response. The question becomes: with zones where they are now and needing to be in 30-60 minutes, what is the plant's minimum required effort?
That answer keeps moving. On a cool morning, the model may raise chilled water supply temperature 6F for the first three hours, reducing compressor loading roughly 15-20% then. It lowers the setting as occupancy and outdoor temperature rise. Chilled water reset has appeared in ASHRAE guidance for decades, but few BMS platforms run it continuously without manual intervention.
Supply air reset follows the same principle. The model identifies the zone with greatest cooling demand, finds the lowest supply air temperature that meets it, and sets the AHU accordingly. Other zones get warmer air than under a fixed 55F setting, so VAV boxes open wider for equivalent cooling. Lower static pressure then reduces fan motor work, adding to chiller savings.
How Savings Reach the Utility Bill
Commercial rates distinguish kWh consumption from kW demand. Demand charges can make up 30-50% of a monthly bill and use the highest 15-minute or 30-minute average kW reading in the period. One hot-afternoon event, when zones cool together, can establish the month's demand charge.
Continuous setpoint optimization often cuts demand by a larger percentage than consumption. It works hardest during high-load periods, which also create the demand peak. Reducing chiller loading through supply air and chilled water adjustments during that event lowers the month's peak.
In an early-access pilot at a mid-size Atlanta office building, a facility with 8 zones across 3 floors recorded a 9% peak-demand reduction and an 11% monthly kWh reduction in its first full billing cycle after automation. Demand made up roughly 40% of total bill savings despite the smaller absolute energy amount.
What This Is Not
Continuous adjustment is not an aggressive temperature setback. Optimization does not mean pushing comfort limits. A 78F occupied-zone target risks discomfort and tenant complaints. The model stays within a defined band, typically 70-76F for cooling and 68-72F for heating, and does not target its edge without occupancy confirmation.
The changes occur below the zone target, in plant settings: the chiller's effort and operating temperature while the zone stays comfortable. A tenant in Zone 4 should notice no difference between fixed-schedule 55F supply air and reset-schedule 57.5F air. The utility bill does.
Required Data and Its Source
The BMS already gathers the needed inputs: zone and supply air temperatures, chilled water supply and return temperatures, outdoor conditions, available occupancy signals, AHU fan speed, and static pressure. The missing link is real-time connection between those streams and a setpoint decision.
DomeSystems connects through BACnet, Modbus, or OPC-UA, reads existing BMS streams, builds the thermal model, and writes new setpoints through the interface your team already uses. No hardware is added. The BMS remains authoritative, while its setpoints change continuously instead of only at commissioning.
The first 30 days are for learning. The system watches zone responses to setpoint changes, load patterns across days and weather, and plant efficiency at different operating points. It then issues adjustments within configurable bounds for team review and approval before autonomous operation begins.