Scope 2 reporting can be mathematically exact while still resting on a false premise. The formula is electricity consumed times the grid emissions factor, producing carbon attributed to the building. The weak point is often the consumption figure itself, an estimate based on schedules that may not reflect how the building operated.
Tracing the Number
At buildings with utility-grade, building-level submeters, electricity data is fairly reliable. The utility meter captures total use, then a regional grid emissions factor from EPA's eGRID database or an equivalent authority converts it to Scope 2 emissions. Technically, that portion works.
The difficulty starts when you ask what produced that use. First, reduction targets require that knowledge: if the goal is to cut building Scope 2 by 15% by 2027, you must identify the operating practices behind consumption before proposing credible reductions. Second, under Local Law 97 (New York), BERDO (Boston), and similar standards, penalties use actual consumption. Showing good-faith improvement requires evidence that the drivers are understood and actively managed.
An Assumption-Based Baseline
Scope 2 baselines usually combine actual utility data with assumed occupancy schedules. Reality begins to diverge at the schedule assumption.
A commissioning model may assume full occupancy Monday through Friday, 8am to 6pm, 50% use during shoulder hours, and no occupants overnight or on weekends. That profile sets HVAC timing and therefore a substantial share of energy use. Under standard weather assumptions, the model forecasts consumption from the schedule.
Most commercial buildings no longer match their commissioning assumptions. Hybrid work lowers weekday occupancy on some days, floor headcounts shift, and zones may serve purposes unlike those in the original design. Yet the BMS can still run the original HVAC schedule. The building then conditions assumed occupants rather than actual ones.
Scope 2 emissions use actual utility consumption. The operating explanation behind that figure, however, may describe a building that did not operate that way during the reporting period.
Attributing Energy by Zone
Zone-level submetering is uncommon in commercial buildings. Meters typically capture electricity by building or floor, not zone. So a building reporting 3,200,000 kWh for the year cannot say what share came from conditioning unoccupied zones.
That missing answer sets the scale of avoidable emissions. If 12% of yearly HVAC use conditioned empty zones during those hours, a realistic outcome where schedules are stale, about 10-15 metric tons of CO2e could be avoided without changing use, tenant comfort, or operating requirements. The source is a schedule assumption that no longer fits reality.
Without zone data, the figure disappears. Total use is reported, and the Scope 2 math appears clean. The 10-15 tons of avoidable emissions remain mixed into the total, alongside necessary operating consumption.
Requirements for Sound Baselining
Sound emissions baselines connect real occupancy with real HVAC schedules and validate that link continuously. This is not an annual measurement and verification (M&V) exercise. It is a continuing comparison of scheduled operation with actual building use.
Suppose a facility's BMS shows Zone 3 held occupied-hour setpoints on 47 weekday afternoons last quarter, while motion sensors show zero occupancy in each window. Those 47 afternoons quantify avoidable emissions. The BMS already contained the evidence; no one was reconciling it.
Occupancy-aware scheduling produces consumption data closer to necessary operations. When actual occupancy, rather than a static schedule, calls for conditioning in each zone, the remaining use is more closely tied to operational need. Emissions reporting becomes easier to defend, and reduction targets become more credible.
The Risk in Schedule-Based Baselines
Schedule-based HVAC does not mean a building is misreporting emissions. Total consumption can be accurate. The risk is an improvement claim built on fiction: a baseline containing avoidable waste from stale schedules is not a fair starting point for efficiency gains. If Scope 2 falls 8% year-over-year, with 5% coming from correcting an occupancy schedule that overconditioned the building for three years, is that new improvement or the removal of old waste?
Technically, both. The distinction matters when reporting to owners, tenants with sustainability commitments, and performance-standard authorities that will scrutinize the operating details behind reported figures.
Credible Alternative
Better utility metering can help, but durable emissions figures require schedules calibrated continuously to occupancy. Updating a building's HVAC schedule near-real-time from observed zone patterns narrows the gap between planned and actual operation. Use that remains afterward is easier to defend as necessary consumption rather than schedule waste.
DomeSystems creates a zone occupancy model from BMS sensor data, room sensors, and available calendar integrations, then adjusts HVAC scheduling from that model. The outcome includes energy savings and a maintained record linking each zone's conditioning to actual use. That record supports a Scope 2 report that explains where consumption came from, not only how much was used.