Work out the energy a demand response event delivered against its baseline, how it compares with the commitment, and the rebound afterwards.
Energy reduced during the event
80.5kWh
Check the values to see a result.
Import is positive, export negative. The programme’s own baseline and settlement rules decide what is paid.
event energy reduction = Σ(baseline − actual) × interval hoursrebound = Σ(post-event actual − baseline) × interval hours
Against its baseline, the site cut 80.5 kWh over 4 intervals, an average of 80.5 kW or 107.3% of the commitment, and took back 33.25 kWh afterwards.
Tip: Rebound matters to a flexibility buyer as much as the event: heating and cooling loads often take the energy back in the next hour.
A demand response event is measured against a baseline: what the site would have used had there been no event. The energy delivered is the difference between baseline and actual demand in each interval, added up over the event. A site 106.25 kW below its baseline on average for an hour has delivered 106.25 kWh, displayed as 106.3 kWh; if it then uses 20 kWh more than its baseline to catch up, the net effect is 86.25 kWh.
E = Σ (baseline − actual) × interval hours
For each interval of the event, subtract the metered demand from the baseline demand, in kW, and multiply by the interval’s length in hours. A 15-minute interval is 0.25 h. Import is positive and export negative, so a site that exports during the event delivers more than its whole load.
Delivery (%) = average reduction ÷ committed reduction × 100
Most programmes pay for a committed reduction in kW. Meeting it on average is not always enough: many settle each interval separately, so an interval below the commitment can cost money even when the average is above it. The calculator counts those intervals.
Rebound = Σ (actual − baseline) × interval hours, after the event
Loads that store energy, such as heating, cooling and refrigeration, catch up after the event and use more than their baseline for a while. The grid operator sees that rebound as new demand, so it matters to the value of the flexibility as much as the event itself.
The baseline is the part that decides what is paid, and it belongs to the programme, not the site. Common methods average the same hours on recent similar days, often adjusted to the site’s demand just before the event, or fit a model of demand against temperature. The arithmetic here is the same whatever baseline the programme uses; enter its baseline values and the metered values interval by interval.
Four 15-minute intervals with reductions of 110, 110, 95 and 110 kW deliver exactly 106.25 kWh, displayed as 106.3 kWh, and average 106.25 kW against a 100 kW commitment. The third interval fell short, which matters if the programme settles each interval. Over the next half hour the site took back 20 kWh.
Energy reduced during the event 106.3 kWh Open in the calculator
The site started 250 kW below its baseline but drifted back over two hours. It delivered 370 kWh, an average of 185 kW, or 92.5% of its 200 kW commitment, with three of the four half-hours below it. A load that recovers during an event, such as a chiller whose building warms up, often shows this shape.
Energy reduced during the event 370 kWh Open in the calculator
Cold stores switched off for an hour cut 80.5 kWh against a 75 kW commitment. When they restart they pull the temperature back down, using 33.25 kWh above the baseline over the next hour, so the net reduction is 47.25 kWh.
Energy reduced during the event 80.5 kWh Open in the calculator
Energy delivered in kWh for a reduction held steady for the whole event, with no rebound.
| Reduction (kW) | 30 minutes (kWh) | 1 hour (kWh) | 2 hours (kWh) | 4 hours (kWh) |
|---|---|---|---|---|
| 25 | 12.5 | 25 | 50 | 100 |
| 50 | 25 | 50 | 100 | 200 |
| 100 | 50 | 100 | 200 | 400 |
| 200 | 100 | 200 | 400 | 800 |
| 500 | 250 | 500 | 1,000 | 2,000 |
| 1,000 | 500 | 1,000 | 2,000 | 4,000 |
An estimate of what the site would have used during the event had it not responded. The programme defines how it is calculated, usually from the same hours on recent similar days. Because nobody can meter what did not happen, the baseline method decides what the site is paid for.
Settlement uses the programme’s own interval, often 15 or 30 minutes, and a reduction that dips within an interval shows only as its average. Metering at the same interval, or shorter, lets the site see what the programme sees.
Not always. A programme that asks for a reduction at the evening peak may not care about extra demand at midnight. It matters when the rebound lands in another peak, and some programmes limit it for that reason.
With interval metering at the site’s connection, or on the loads that respond, and a controller that acts on the operator’s signal. See the role of IoT in demand response.
A ZDR measures three-phase demand and switches loads locally when an event starts; a ZEM meters the other circuits, so both the response and the baseline come from the same data.
