# Sankey Diagram: Visualize & Optimize Industrial Energy Flows

Industrial energy flow visualization using Sankey diagrams

# Sankey Diagram: The Essential Tool for Visualizing and Optimizing Your Energy Flows

In today's industrial landscape where every kilowatt-hour counts, **Sankey diagrams** have become the strategic tool for understanding, analyzing, and optimizing your energy flows with unprecedented precision.

Industrial companies using **Sankey diagrams** for their **energy balance** identify on average **10-30% additional savings** compared to traditional energy tracking methods.

This comprehensive guide explains how to implement this powerful tool, interpret your **energy flows**, and transform these insights into concrete optimization actions.

## Executive Summary – Energy Sankey Diagrams

The **Sankey diagram** is not just a visualization tool: it's an **energy flow analysis** methodology that reveals invisible losses, quantifies inefficiencies, and prioritizes optimization actions. This article explains how to create and interpret these energy schematics, presents 4 concrete industrial use cases, and shows how the Wattnow platform automatically generates dynamic **Sankey diagrams** from your energy data, identifying **10-30% potential savings**.

Fundamentals

## What is an Energy Sankey Diagram?

Discover the basic principles of this **energy flow visualization** tool that revolutionizes industrial consumption analysis.

### Definition and Origin

A **Sankey diagram** is a graphical representation of energy flows where arrow widths are proportional to the amount of energy flowing. Invented by Captain Sankey in 1898 to analyze steam engine efficiency, it's now indispensable for **industrial energy balance**.

### Proportionality Principle

The width of each arrow corresponds exactly to the energy flow it represents. An arrow twice as wide = twice as much energy. This visual principle immediately identifies the most energy-intensive processes and main losses.

### Flow Hierarchy

The diagram organizes flows from left (sources) to right (uses). Each bifurcation shows how energy distributes between different processes, highlighting losses at each transformation stage.

### Why It's Revolutionary for Industry

Unlike Excel tables or classic charts, the **Sankey diagram** makes the invisible visible: it shows not only how much energy is consumed, but especially **where it goes, how it transforms, and where it's lost**. In an automobile factory for example, it reveals that 40% of incoming electrical energy is ultimately lost as unrecovered waste heat.

## 4 Concrete Use Cases of Sankey Diagrams in Industry

### Automotive Plant

**Problem:** High energy bill without understanding responsible processes.

**Sankey Solution:** Flow visualization from electrical intake to workshops (presses, painting, assembly).

**Result:** Identification that 35% of painting workshop energy is lost in oversized ventilation.

### Data Center

**Problem:** High PUE (Power Usage Effectiveness) at 1.8.

**Sankey Solution:** Mapping electrical flows between servers, cooling, lighting, losses.

**Result:** Revelation that 45% of energy serves cooling, enabling free cooling optimization and PUE reduction to 1.4.

### Thermal Power Plant

**Problem:** Low overall efficiency at 38%.

**Sankey Solution:** Detailed analysis of stack, condensation, auxiliary losses.

**Result:** Identification that 12% of losses come from absence of flue gas heat recovery.

### Chemical Site

**Problem:** Uncontrolled process energy costs.

**Sankey Solution:** Tracking energy from utilities (steam, compressed air) to reactors.

**Result:** Discovery that 28% of produced steam is lost through defective steam traps.

## How to Create and Interpret an Energy Sankey Diagram

Follow this 5-step methodology to implement this **consumption optimization** tool in your company.

1. **Collect Energy Data**  
   Measure consumptions at each key point: energy intakes (electricity, gas, purchased steam), transformations (boilers, compressors), final uses (machines, processes). Use IoT sensors for optimal accuracy.

2. **Structure the Flows**  
   Organize data in hierarchy: incoming energies → transformations → final uses → losses. Define consistent units (kWh, GJ, toe) and conversion coefficients.

3. **Generate the Diagram**  
   Use specialized tools (Wattnow, Python + Plotly, online tools) to create the visualization. The Wattnow platform automates this step from your IoT data.

4. **Analyze Insights**  
   Visually identify: widest flows (priority processes), proportionally significant losses, inefficient bifurcations, gaps between similar units.

5. **Define Corrective Actions**  
   Prioritize actions according to savings potential: reduce widest losses, optimize inefficient transformations, recover waste energies.

### Pitfalls to Avoid

- **Incomplete data:** A **Sankey diagram** based on partial data gives a distorted view. Measure all significant flows (>5% of total consumption).
- **Inconsistent units:** Mixing electrical and thermal kWh without appropriate conversion coefficients.
- **Insufficient frequency:** An annual diagram masks seasonal variations and temporary malfunctions.

## Sankey 2.0: Dynamic Energy Visualization with Wattnow

Wattnow transforms the traditional **Sankey diagram** into an operational management tool with advanced features for Industry 4.0.

### Automatic Generation

No more manually creating your **energy schematics**. Wattnow automatically generates Sankey diagrams from your IoT sensor data, with real-time updates.

### Multi-Granularity Analysis

Zoom from complete industrial site down to a specific machine. Compare diagrams between different workshops, shift teams, or periods (day/night, summer/winter).

### Intelligent Alerts

Receive automatic alerts when your Sankey diagram morphology changes abnormally: sudden widening of a loss flow, modification of proportions between uses.

## FAQ – Energy Sankey Diagrams

How many measurement points are needed for a reliable Sankey diagram?

For an average industrial site, we recommend 15-30 strategic measurement points: main energy intakes (3-5 points), outputs of main transformations (boilers, compressors: 4-6 points), significant final uses (>5% of total consumption: 8-15 points), and identified loss points (2-4 points).

Does the Sankey diagram replace regulatory energy audits?

No, it complements and enriches them. Energy audits are periodic regulatory analyses, while Sankey diagrams are continuous management tools.

Can Sankey diagrams be created for other flows besides energy?

Absolutely! The Sankey diagram principle applies to any quantifiable flow: raw materials (kg), water (m³), waste (tons), CO₂ (tCO₂eq), or even financial flows.

What's the difference between a Sankey diagram and a classic energy balance?

The energy balance gives numbers (tables), the Sankey diagram gives vision (image).

How does Wattnow integrate with our existing monitoring tools?

Wattnow connects to most industrial systems via standard protocols (Modbus TCP, OPC-UA, REST API, MQTT). We can integrate your existing data (SCADA, CMMS, PLCs) and complement if necessary with our IoT sensors.