Building Energy Use Sankey Diagram: Editable Template
Follow an office building's energy from grid, solar and gas through the boiler and end uses to useful energy and losses with an editable Sankey. Illustrative figures.
A building energy Sankey follows every megawatt-hour from the meter to where it ends up: lighting, heating, cooling and equipment, or lost as waste heat. This one covers a mid-sized office over a year.
Three inputs feed the building: grid electricity, rooftop solar and natural gas. Electricity and gas take different routes. Electricity is shared directly between four end uses, while gas first passes through a boiler, which loses some of it before the rest heats the rooms and the hot water.
On the right, every end use splits into useful energy, the light, comfort and computing the building exists to provide, and losses, mostly waste heat. With both outcomes in one diagram you can compare where a building is wasteful, not only where it is hungry. The figures are invented and sized so that every node balances.
How to read this diagram
- The building takes in 980 MWh a year: 520 from the grid, 70 from rooftop solar and 390 from gas. Gas is about 40% of the input and is used only for heat.
- Solar covers about 12% of the building's electricity (70 of 590 MWh). Equipment and IT is the largest electricity user at 290 MWh, almost half of it.
- About 74% of the input (722 of 980 MWh) ends up as useful energy. The boiler alone loses 55 MWh, 14% of the gas it burns.
- Space heating is the largest single end use at 300 MWh, but the losses are spread out: equipment and IT wastes 83 MWh, more than the boiler does.
The data behind it
Invented annual figures in megawatt-hours for an imaginary office building, balanced so that every node adds up. Not metered data, an energy audit or an energy performance rating.
| From | To | Amount (MWh) |
|---|---|---|
| Grid electricity | Building electricity | 520 |
| Rooftop solar | Building electricity | 70 |
| Natural gas | Boiler | 390 |
| Building electricity | Hot water | 40 |
| Building electricity | Ventilation and cooling | 165 |
| Building electricity | Lighting | 95 |
| Building electricity | Equipment and IT | 290 |
| Boiler | Space heating | 300 |
| Boiler | Hot water | 35 |
| Boiler | Waste heat and losses | 55 |
| Space heating | Useful energy | 255 |
| Space heating | Waste heat and losses | 45 |
| Hot water | Useful energy | 60 |
| Hot water | Waste heat and losses | 15 |
| Ventilation and cooling | Useful energy | 120 |
| Ventilation and cooling | Waste heat and losses | 45 |
| Lighting | Useful energy | 80 |
| Lighting | Waste heat and losses | 15 |
| Equipment and IT | Useful energy | 207 |
| Equipment and IT | Waste heat and losses | 83 |
The same data as CSV
source,target,value
Grid electricity,Building electricity,520
Rooftop solar,Building electricity,70
Natural gas,Boiler,390
Building electricity,Hot water,40
Building electricity,Ventilation and cooling,165
Building electricity,Lighting,95
Building electricity,Equipment and IT,290
Boiler,Space heating,300
Boiler,Hot water,35
Boiler,Waste heat and losses,55
Space heating,Useful energy,255
Space heating,Waste heat and losses,45
Hot water,Useful energy,60
Hot water,Waste heat and losses,15
Ventilation and cooling,Useful energy,120
Ventilation and cooling,Waste heat and losses,45
Lighting,Useful energy,80
Lighting,Waste heat and losses,15
Equipment and IT,Useful energy,207
Equipment and IT,Waste heat and losses,83How it works
List the inputs and the meters behind them
Add one node per energy source you buy or generate, with its annual or monthly total from bills or sub-meters.
Route each carrier to its end uses
Send electricity to the systems that use it. If a fuel passes through a boiler or other plant, give that plant its own node so the conversion loss is visible.
Close the balance with a losses node
Where you know a system's efficiency, split it into useful energy and losses. Where you do not, estimate and say so in your data note.
Frequently asked questions
Can I use sub-meter readings instead of estimates?
Yes. Use meter data wherever you have it and estimates for the rest, and keep one unit (kWh or MWh) for the whole chart so the ribbons stay comparable.
How do I show district heating or a heat pump?
Add district heat as another input node. For a heat pump, add a conversion node between electricity and space heating, plus ambient heat as an extra input so the node still balances.
Is this an energy performance certificate?
No. It is a visual for explaining and comparing where energy goes. Use a qualified assessment for certificates and compliance.
Edit this building energy Sankey
Open the template as your own chart and enter your building's inputs, systems and losses.