Energy is expressed in kilowatt-hours (kWh), megawatt-hours (MWh), gigajoules (GJ) and terajoules (TJ). The following applies: 1 MWh = 3.6 GJ, 1 GJ = 0.2778 MWh and 1 TJ = 1,000 GJ = 277.78 MWh.
Conversion table
| Unit | kWh | MWh | GJ | TJ |
|---|---|---|---|---|
| 1 kWh | 1 | 0,001 | 0,0036 | 0,0000036 |
| 1 MWh | 1 000 | 1 | 3,6 | 0,0036 |
| 1 GJ | 277,78 | 0,2778 | 1 | 0,001 |
| 1 TJ | 277 778 | 277,78 | 1 000 | 1 |
Legal thresholds
Czech Act No. 406/2000 Coll. on Energy Management states the thresholds in terajoules: 10 TJ corresponds to roughly 2 778 MWh (the threshold for an energy audit) and 85 TJ to roughly 23 611 MWh (the threshold for certified ISO 50001). The comparison includes consumption of all forms of energy, i.e. electricity, gas, heat and fuels, averaged over the last three consecutive calendar years. Fuels are converted according to their calorific value.
Example from manufacturing
Illustrative example: a plant consumes 1 500 MWh of electricity and 6 000 GJ of natural gas per year. The gas equals 6 000 × 0.2778 = 1 667 MWh. In total that is 3 167 MWh, or roughly 11.4 TJ. This exceeds the 10 TJ threshold, so the plant is subject to the energy audit obligation (provided this is the three-year average). Our obligation test will do the calculation for you.
Frequently asked questions
How many MWh is 10 TJ?
Roughly 2,778 MWh (10,000 GJ divided by 3.6). Above this consumption, the energy audit obligation applies.
How many MWh is 85 TJ?
Roughly 23,611 MWh. Above this consumption, the law requires a certified ISO 50001 system.