Scatter Plots
Understanding consumption vs DJU scatter plots for energy analysis.
The scatter plot on the CVC Auto-Comparison page shows the relationship between energy consumption and heating/cooling degree days (DJU). It appears at the bottom of the CVC auto-comparison page, labeled Consommation vs Degres-Jours.
How to read the scatter plot
| Element | Description |
|---|---|
| X-axis | DJU value (heating/cooling degree days, representing weather intensity) |
| Y-axis | Electricity consumption (kWh per m2) |
| Each point | One day's measurement, color-coded by period (green = current, orange = previous) |
| Trend line | Linear regression showing the expected consumption-to-weather relationship |
What the scatter plot tells you
| Pattern | Meaning |
|---|---|
| Tight cluster around trend line | Consumption is predictable and weather-driven. HVAC responds consistently. |
| Points far above the trend | Unexpectedly high consumption. Could indicate equipment malfunction or manual overrides. |
| Points far below the trend | Efficient periods, reduced operations, or the site was partially closed. |
| Steep trend line | The site is highly weather-sensitive (HVAC-dominated). |
| Flat trend line | Consumption is mostly weather-independent (base load-dominated). |
Comparing periods
The scatter plot shows both the current period and previous period on the same chart. This lets you visually compare:
- Whether the trend line shifted (indicating a change in operational efficiency)
- Whether outlier days occurred in one period but not the other
- Whether the site became more or less weather-sensitive
Practical example
If you see the current period's points consistently below the previous period's trend line at the same DJU values, your HVAC efficiency improved. This could confirm the impact of a maintenance intervention, thermostat adjustment, or insulation upgrade.