Flow visualization tool

Where energy
finds its shape

SankeyLoop turns complex energy and material flows into clear, interactive diagrams. No login. No installation. Just drag, drop, and share.

Open the App See examples ↓
Thermal gradients
Temperature-coded flows
Free forever
Gas Boiler Process Chiller Heat Cool Loss 180°C 45°C 5°C
180 °C
5 °C

About

What is a Sankey diagram?

A Sankey diagram is a flow visualization where the width of each arrow is proportional to the quantity it represents — making it immediately obvious where the big flows are, where energy is lost, and where efficiencies can be found.

First used by Irish engineer Matthew Sankey in 1898 to visualize steam engine efficiency, they are now the go-to tool for engineers, sustainability analysts, and process designers working with energy balances, material flows, supply chains, and carbon accounts.

SankeyLoop adds a thermal gradient layer: flow colors encode temperature, so hot and cold streams are visually distinct at a glance — no legend required.

100 kW 60 kW 40 kW width ∝ flow

Examples

Start from a template

Click any example to open it directly in the app.

Energy
Steam & Heat System
Industrial boiler, steam distribution, condensate return, and heat recovery — the classic SankeyLoop demo.
Load example →
Buildings
Building Energy Balance
Heating, cooling, ventilation, lighting, and plug loads in a commercial building.
Load example →
Power
Electricity Grid Mix
Solar, wind, gas, and hydro generation flowing to residential, industrial, and commercial demand.
Load example →
Water
Water Treatment Plant
Raw intake through filtration, treatment, and distribution to potable and non-potable outputs.
Load example →
Industry
Manufacturing Flow
Raw materials and components through production stages to finished products and waste streams.
Load example →
Sustainability
GHG Emissions Account
Scope 1, 2, and 3 emissions by source and category, with renewable offsets shown as separate flows.
Load example →

Features

Everything you need,
nothing you don't

🌡️
Thermal gradient colors
Assign a temperature to each flow. Hot streams glow red, cold streams turn blue — automatically.
🖱️
Drag & remember
Drag any node to where it belongs. Change colors, opacity, or fonts — nodes stay exactly where you put them.
💾
Export & import
Save your complete diagram — layout, positions, and all settings — as a single JSON file. Reopen it exactly as you left it.
📋
Paste from Excel
Copy a range of cells directly from Excel or Google Sheets and paste it into the flow table. No reformatting needed.
👻
Ghost flows
Zero-value flows render as faint hairlines, keeping the connection visible even when no flow is currently passing through.
🔄
Negative flows
Enter a negative value and the flow direction reverses automatically — useful for return lines and recirculation loops.
🌙
Light & dark theme
Switch between a clean white canvas and a dark engineering-style background with one click.
🔒
No login, no server
Runs entirely in your browser. Your data never leaves your machine. No account required, ever.

Ready to map your flows?

Free, instant, no setup required.

Open SankeyLoop